1
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Zhang H, Krynski M, Fortes AD, Saunders TG, Palma M, Hao Y, Krok F, Yan H, Abrahams I. Origin of Polarization in Bismuth Sodium Titanate-Based Ceramics. J Am Chem Soc 2024; 146:5569-5579. [PMID: 38353048 PMCID: PMC10910510 DOI: 10.1021/jacs.3c13927] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2023] [Revised: 01/31/2024] [Accepted: 02/01/2024] [Indexed: 02/29/2024]
Abstract
The classical view of the structural changes that occur at the ferroelectric transition in perovskite-structured systems, such as BaTiO3, is that polarization occurs due to the off-center displacement of the B-site cations. Here, we show that in the bismuth sodium titanate (BNT)-based composition 0.2(Ba0.4Sr0.6TiO3)-0.8(Bi0.5Na0.5TiO3), this model does not accurately describe the structural situation. Such BNT-based systems are of interest as lead-free alternatives to currently used materials in a variety of piezo-/ferroelectric applications. A combination of high-resolution powder neutron diffraction, impedance spectroscopy, and ab initio calculations reveals that Ti4+ contributes less than a third in magnitude to the overall polarization and that the displacements of the O2- ions and the A-site cations, particularly Bi3+, are very significant. The detailed examination of the ferroelectric transition in this system offers insights applicable to the understanding of such transitions in other ferroelectric perovskites, particularly those containing lone pair elements.
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Affiliation(s)
- Hangfeng Zhang
- Department of Chemistry, Queen Mary University of London, Mile End Road, London E1 4NS, U.K
- School of Engineering and Materials Science, Queen Mary University of London, Mile End Road, London E1 4NS, U.K
| | - Marcin Krynski
- Faculty of Physics, Warsaw University of Technology, Koszykowa 75, 00-662 Warszawa, Poland
| | - A Dominic Fortes
- STFC ISIS Facility, Rutherford Appleton Laboratory, Chilton Didcot, Oxfordshire OX11 OQX, U.K
| | - Theo Graves Saunders
- School of Engineering and Materials Science, Queen Mary University of London, Mile End Road, London E1 4NS, U.K
| | - Matteo Palma
- Department of Chemistry, Queen Mary University of London, Mile End Road, London E1 4NS, U.K
| | - Yang Hao
- School of Electronic Engineering and Computer Science, Queen Mary University of London, Mile End Road, London E1 4NS, U.K
| | - Franciszek Krok
- Faculty of Physics, Warsaw University of Technology, Koszykowa 75, 00-662 Warszawa, Poland
| | - Haixue Yan
- School of Engineering and Materials Science, Queen Mary University of London, Mile End Road, London E1 4NS, U.K
| | - Isaac Abrahams
- Department of Chemistry, Queen Mary University of London, Mile End Road, London E1 4NS, U.K
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2
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Hou X, Coker JF, Yan J, Shi X, Azzouzi M, Eisner FD, McGettrick JD, Tuladhar SM, Abrahams I, Frost JM, Li Z, Dennis TJS, Nelson J. Structure-Property Relationships for the Electronic Applications of Bis-Adduct Isomers of Phenyl-C 61 Butyric Acid Methyl Ester. Chem Mater 2024; 36:425-438. [PMID: 38222935 PMCID: PMC10782444 DOI: 10.1021/acs.chemmater.3c02353] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/13/2023] [Revised: 11/26/2023] [Accepted: 11/27/2023] [Indexed: 01/16/2024]
Abstract
Higher adducts of a fullerene, such as the bis-adduct of PCBM (bis-PCBM), can be used to achieve shallower molecular orbital energy levels than, for example, PCBM or C60. Substituting the bis-adduct for the parent fullerene is useful to increase the open-circuit voltage of organic solar cells or achieve better energy alignment as electron transport layers in, for example, perovskite solar cells. However, bis-PCBM is usually synthesized as a mixture of structural isomers, which can lead to both energetic and morphological disorder, negatively affecting device performance. Here, we present a comprehensive study on the molecular properties of 19 pure bis-isomers of PCBM using a variety of characterization methods, including ultraviolet photoelectron spectroscopy, thermal gravimetric analysis, differential scanning calorimetry, single crystal structure, and (time-dependent) density functional theory calculation. We find that the lowest unoccupied molecular orbital of such bis-isomers can be tuned to be up to 170 meV shallower than PCBM and up to 100 meV shallower than the mixture of unseparated isomers. The isolated bis-isomers also show an electron mobility in organic field-effect transistors of up to 4.5 × 10-2 cm2/(V s), which is an order of magnitude higher than that of the mixture of bis-isomers. These properties enable the fabrication of the highest performing bis-PCBM organic solar cell to date, with the best device showing a power conversion efficiency of 7.2%. Interestingly, we find that the crystallinity of bis-isomers correlates negatively with electron mobility and organic solar cell device performance, which we relate to their molecular symmetry, with a lower symmetry leading to more amorphous bis-isomers, less energetic disorder, and higher dimensional electron transport. This work demonstrates the potential of side chain engineering for optimizing the performance of fullerene-based organic electronic devices.
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Affiliation(s)
- Xueyan Hou
- Department
of Physics, Imperial College London, London SW7 2AZ, U.K.
- School
of Physical and Chemical Sciences, Queen
Mary University of London, London E1 4NS, U.K.
| | - Jack F. Coker
- Department
of Physics, Imperial College London, London SW7 2AZ, U.K.
| | - Jun Yan
- Department
of Physics, Imperial College London, London SW7 2AZ, U.K.
- School
of Science and Engineering, The Chinese
University of Hong Kong, Shenzhen, Guangdong Province 518172, P. R. China
| | - Xingyuan Shi
- Department
of Physics, Imperial College London, London SW7 2AZ, U.K.
| | - Mohammed Azzouzi
- Department
of Physics, Imperial College London, London SW7 2AZ, U.K.
| | - Flurin D. Eisner
- Department
of Physics, Imperial College London, London SW7 2AZ, U.K.
| | | | | | - Isaac Abrahams
- School
of Physical and Chemical Sciences, Queen
Mary University of London, London E1 4NS, U.K.
| | - Jarvist M. Frost
- Department
of Physics, Imperial College London, London SW7 2AZ, U.K.
| | - Zhe Li
- School
of Engineering and Materials Sciences, Queen
Mary University of London, London E1 4NS, U.K.
| | - T. John S. Dennis
- Department
of Chemistry, Xi’an Jiaotong-Liverpool
University, Suzhou 215123, China
| | - Jenny Nelson
- Department
of Physics, Imperial College London, London SW7 2AZ, U.K.
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3
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Jing P, Stevenson S, Lu H, Ren P, Abrahams I, Gregory DH. Pillared Vanadium Molybdenum Disulfide Nanosheets: Toward High-Performance Cathodes for Magnesium-Ion Batteries. ACS Appl Mater Interfaces 2023; 15:51036-51049. [PMID: 37874903 PMCID: PMC10636724 DOI: 10.1021/acsami.3c10287] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/14/2023] [Accepted: 10/09/2023] [Indexed: 10/26/2023]
Abstract
If magnesium-ion batteries (MIBs) are to be seriously considered for next-generation energy storage, then a number of major obstacles need to be overcome. The lack of reversible cathode materials with sufficient capacity and cycle life is one of these challenges. Here, we report a new MIB cathode constructed of vertically stacked vanadium molybdenum sulfide (VMS) nanosheets toward addressing this challenge. The integration of vanadium within molybdenum sulfide nanostructures acts so as to improve the total conductivity, enhancing charge transfer, and to produce abundant lattice defects, improving both the accommodation and transport of Mg2+. Additionally, electrolyte additive-induced interlayer expansion provides a means to admit Mg2+ cations into the electrode structure and thus enhance their diffusion. The VMS nanosheets are capable of exhibiting capacities of 211.3 and 128.2 mA h g-1 at current densities of 100 and 1000 mA g-1, respectively. The VMS nanosheets also demonstrate long-term cycling stability, retaining 82.7% of the maximum capacity after 500 cycles at a current density of 1000 mA h g-1. These results suggest that VMS nanosheets could be promising candidates for high-performance cathodes in MIBs.
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Affiliation(s)
- Pengcheng Jing
- WestCHEM,
School of Chemistry, Joseph Black Building, University of Glasgow, Glasgow G12 8QQ, U.K.
| | - Siobhan Stevenson
- WestCHEM,
School of Chemistry, Joseph Black Building, University of Glasgow, Glasgow G12 8QQ, U.K.
| | - Huimin Lu
- School
of Material Science and Engineering, Beihang
University, Beijing 100083, China
| | - Peng Ren
- Department
of Chemistry, Queen Mary University of London, Mile End Road, London E1 4NS, U.K.
| | - Isaac Abrahams
- Department
of Chemistry, Queen Mary University of London, Mile End Road, London E1 4NS, U.K.
| | - Duncan H. Gregory
- WestCHEM,
School of Chemistry, Joseph Black Building, University of Glasgow, Glasgow G12 8QQ, U.K.
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4
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Abstract
New solid electrolytes are crucial for the development of all-solid-state lithium batteries with advantages in safety and energy densities over current liquid electrolyte systems. While some of the best solid-state Li+-ion conductors are based on sulfides, their air sensitivity makes them less commercially attractive, and attention is refocusing on air-stable oxide-based systems. Among these, the LISICON-structured systems, such as Li2+2xZn1-xGeO4 and Li3+xV1-xGexO4, have been relatively well studied. However, other systems such as the Li4GeO4-Li2MoO4 system, which also show LISICON-type structures, have been relatively little explored. In this work, the Li4-2xGe1-xMoxO4 solid solution is investigated systematically, including the solid solution limit, structural stability, local structure, and the corresponding electrical behavior. It is found that a γ-LISICON structured solution is formed in the range of 0.1 ≤ x < 0.4, differing in structure from the two end members, Li4GeO4 and Li2MoO4. With increasing Mo content, the β-phase becomes increasingly more stable than the γ-phase, and at x = 0.5, a pure β-phase (β-Li3Ge0.5Mo0.5O4) is readily isolated. The structure of this previously unknown compound is presented, along with details of the defect structure of Li3.6Ge0.8Mo0.2O4 (x = 0.2) based on neutron diffraction data. Two basic types of defects are identified in Li3.6Ge0.8Mo0.2O4 involving interstitial Li+-ions in octahedral sites, with evidence for these coming together to form larger defect clusters. The x = 0.2 composition shows the highest conductivity of the series, with values of 1.11 × 10-7 S cm-1 at room temperature rising to 5.02 × 10-3 S cm-1 at 250 °C.
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Affiliation(s)
- Ludan Zhang
- Department of Chemistry, Queen Mary University of London, Mile End Road, London E1 4NS, U.K
- Shenzhen CAPCHEM Technology Company Limited, Pingshan District, Shenzhen 518118, China
| | - Marcin Malys
- Faculty of Physics, Warsaw University of Technology, Koszykowa 75, Warszawa 00-662, Poland
| | - Jan Jamroz
- Faculty of Physics, Warsaw University of Technology, Koszykowa 75, Warszawa 00-662, Poland
| | - Franciszek Krok
- Faculty of Physics, Warsaw University of Technology, Koszykowa 75, Warszawa 00-662, Poland
| | - Wojciech Wrobel
- Faculty of Physics, Warsaw University of Technology, Koszykowa 75, Warszawa 00-662, Poland
| | - Stephen Hull
- Science and Technology Facilities Council, ISIS Facility, Rutherford Appleton Laboratory, Chilton, Didcot, Oxofordshire OX11 OQX, U.K
| | - Haixue Yan
- School of Engineering and Materials Science, Queen Mary University of London, Mile End Road, London E1 4NS, U.K
| | - Isaac Abrahams
- Department of Chemistry, Queen Mary University of London, Mile End Road, London E1 4NS, U.K
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5
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Foroutan F, Kyffin BA, Nikolaou A, Merino-Gutierrez J, Abrahams I, Kanwal N, Knowles JC, Smith AJ, Smales GJ, Carta D. Highly porous phosphate-based glasses for controlled delivery of antibacterial Cu ions prepared via sol-gel chemistry. RSC Adv 2023; 13:19662-19673. [PMID: 37396829 PMCID: PMC10308344 DOI: 10.1039/d3ra02958a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2023] [Accepted: 06/07/2023] [Indexed: 07/04/2023] Open
Abstract
Mesoporous glasses are a promising class of bioresorbable biomaterials characterized by high surface area and extended porosity in the range of 2 to 50 nm. These peculiar properties make them ideal materials for the controlled release of therapeutic ions and molecules. Whilst mesoporous silicate-based glasses (MSG) have been widely investigated, much less work has been done on mesoporous phosphate-based glasses (MPG). In the present study, MPG in the P2O5-CaO-Na2O system, undoped and doped with 1, 3, and 5 mol% of Cu ions were synthesized via a combination of the sol-gel method and supramolecular templating. The non-ionic triblock copolymer Pluronic P123 was used as a templating agent. The porous structure was studied via a combination of Scanning Electron Microscopy (SEM), Small-Angle X-ray Scattering (SAXS), and N2 adsorption-desorption analysis at 77 K. The structure of the phosphate network was investigated via solid state 31P Magic Angle Spinning Nuclear Magnetic Resonance (31P MAS-NMR) and Fourier Transform Infrared (FTIR) spectroscopy. Degradation studies, performed in water via Inductively Coupled Plasma-Optical Emission Spectroscopy (ICP-OES), showed that phosphates, Ca2+, Na+ and Cu ions are released in a controlled manner over a 7 days period. The controlled release of Cu, proportional to the copper loading, imbues antibacterial properties to MPG. A significant statistical reduction of Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) bacterial viability was observed over a 3 days period. E. coli appeared to be more resistant than S. aureus to the antibacterial effect of copper. This study shows that copper doped MPG have great potential as bioresorbable materials for controlled delivery of antibacterial ions.
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Affiliation(s)
- Farzad Foroutan
- School of Chemistry and Chemical Engineering, University of Surrey Guildford UK
| | - Benjamin A Kyffin
- School of Chemistry and Chemical Engineering, University of Surrey Guildford UK
| | - Athanasios Nikolaou
- School of Chemistry and Chemical Engineering, University of Surrey Guildford UK
| | | | - Isaac Abrahams
- Department of Chemistry, Queen Mary University of London Mile End Road London E1 4NS UK
| | - Nasima Kanwal
- Department of Chemistry, Queen Mary University of London Mile End Road London E1 4NS UK
| | - Jonathan C Knowles
- Division of Biomaterials and Tissue Engineering, University College London London UK
- Department of Nanobiomedical Science & BK21 PLUS NBM Global Research Center for Regenerative Medicine, Dankook University Cheonan Republic of Korea
- UCL Eastman-Korea Dental Medicine Innovation Centre, Dankook University Cheonan Republic of Korea
| | - Andrew J Smith
- Diamond Light Source Ltd, Diamond House, Harwell Science and Innovation Campus Didcot, Oxfordshire OX11 0DE UK
| | - Glen J Smales
- Bundesanstalt für Materialforschung und -prüfung (BAM) Berlin Germany
| | - Daniela Carta
- School of Chemistry and Chemical Engineering, University of Surrey Guildford UK
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6
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Yue Y, Dzięgielewska A, Zhang M, Hull S, Krok F, Whiteley RM, Toms H, Malys M, Huang X, Krynski M, Miao P, Yan H, Abrahams I. Local Structure in α-BIMEVOXes (ME = Ge, Sn). Chem Mater 2023; 35:189-206. [PMID: 36644215 PMCID: PMC9835824 DOI: 10.1021/acs.chemmater.2c03001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/30/2022] [Revised: 12/11/2022] [Indexed: 06/17/2023]
Abstract
The BIMEVOXes are among the best oxide ion conductors at low and intermediate temperatures. Their high conductivity is associated with local defect structure. In this work, the local structures of two BIMEVOX compositions, Bi2V0.9Ge0.1O5.45 and Bi2V0.95Sn0.05O5.475, are examined using total neutron and X-ray scattering methods, with both compositions exhibiting the ordered α-phase at 25 °C and the disordered γ-phase at 700 °C. While the diffraction data for the α-phase do not allow for the polar (C2) and nonpolar (C2/m) structures to be readily distinguished, measurements of dielectric permittivity suggest the α-phase is weakly ferroelectric in character, consistent with calculations of spontaneous polarization based on a combination of density functional calculations and machine learning methodology. Reverse Monte Carlo (RMC) analysis of total scattering data reveals Ge preferentially adopts tetrahedral geometry at both temperatures, while Sn is found to predominantly adopt octahedral coordination in the α-phase and tetrahedral coordination in the γ-phase. In all cases, V polyhedra are found to consist of tetrahedral, pentacoordinate, and octahedral geometries, as also predicted by the crystallographic analysis and confirmed by 51V solid state NMR spectroscopy. Although similar long-range structures are observed at room temperature, the oxide ion vacancy distributions were found to be quite different between the two studied compositions, with a nonrandom deficiency in vacancy pairs in the second-nearest shell along the ⟨100⟩ tetragonal direction for BIGEVOX10, compared with a long-distance (>8.0 Å) ordering of equatorial vacancies for BISNVOX05. This is attributed to the differences in the preferred coordination geometries of the substituent cations in the two systems. Impedance spectroscopy measurements reveal both compositions show high conductivity in the order of 10-1 S cm-1 at 600 °C.
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Affiliation(s)
- Yajun Yue
- Department
of Chemistry, Queen Mary University of London, Mile End Road, LondonE1 4NS, United
Kingdom
- Institute
of High Energy Physics, Chinese Academy
of Sciences, Beijing100049, China
| | | | - Man Zhang
- School
of Engineering and Materials Science, Queen
Mary University of London, Mile End Road, LondonE1 4NS, United Kingdom
| | - Stephen Hull
- Science
and Technology Facilities Council, ISIS
Facility, Rutherford Appleton Laboratory, Chilton, Didcot, OxonOX11 OQX, United
Kingdom
| | - Franciszek Krok
- Faculty
of Physics, Warsaw University of Technology, ul. Koszykowa 75, 00-662Warsaw, Poland
| | - Richard M. Whiteley
- Science
and Technology Facilities Council, ISIS
Facility, Rutherford Appleton Laboratory, Chilton, Didcot, OxonOX11 OQX, United
Kingdom
| | - Harold Toms
- Department
of Chemistry, Queen Mary University of London, Mile End Road, LondonE1 4NS, United
Kingdom
| | - Marcin Malys
- Faculty
of Physics, Warsaw University of Technology, ul. Koszykowa 75, 00-662Warsaw, Poland
| | - Xuankai Huang
- Department
of Chemistry, Queen Mary University of London, Mile End Road, LondonE1 4NS, United
Kingdom
| | - Marcin Krynski
- Faculty
of Physics, Warsaw University of Technology, ul. Koszykowa 75, 00-662Warsaw, Poland
| | - Ping Miao
- Institute
of High Energy Physics, Chinese Academy
of Sciences, Beijing100049, China
| | - Haixue Yan
- School
of Engineering and Materials Science, Queen
Mary University of London, Mile End Road, LondonE1 4NS, United Kingdom
| | - Isaac Abrahams
- Department
of Chemistry, Queen Mary University of London, Mile End Road, LondonE1 4NS, United
Kingdom
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7
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Zhang H, Fortes AD, Giddens H, Saunders TG, Palma M, Abrahams I, Yan H, Hao Y. Antiferroelectric-like Behavior in a Lead-Free Perovskite Layered Structure Ceramic. Inorg Chem 2022; 61:20316-20325. [PMID: 36472578 PMCID: PMC9768747 DOI: 10.1021/acs.inorgchem.2c02726] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Antiferroelectric (AFE) materials have been intensively studied due to their potential uses in energy storage applications and energy conversion. These materials are characterized by double polarization-electric field (P-E) hysteresis loops and nonpolar crystal structures. Unusually, in the present work, Sr1.68La0.32Ta1.68Ti0.32O7 (STLT32), Sr1.64La0.36Ta1.64Ti0.36O7 (STLT36), and Sr1.85Ca0.15Ta2O7 (SCT15), lead-free perovskite layered structure (PLS) materials, are shown to exhibit AFE-like double P-E hysteresis loops despite maintaining a polar crystal structure. The double hysteresis loops are present over wide ranges of electric field and temperature. While neutron diffraction and piezoresponse force microscopy results indicate that the STLT32 system should be ferroelectric at room temperature, the observed AFE-like electrical behavior suggests that the electrical response is dominated by a weakly polar phase with a field-induced transition to a more strongly polar phase. Variable-temperature dielectric measurements suggest the presence of two-phase transitions in STLT32 at ca. 250 and 750 °C. The latter transition is confirmed by thermal analysis and is accompanied by structural changes in the layers, such as in the degree of octahedral tilting and changes in the perovskite block width and interlayer gap, associated with a change from non-centrosymmetric to centrosymmetric structures. The lower-temperature transition is more diffuse in nature but is evidenced by subtle changes in the lattice parameters. The dielectric properties of an STLT32 ceramic at microwave frequencies was measured using a coplanar waveguide transmission line and revealed stable permittivity from 1 kHz up to 20 GHz with low dielectric loss. This work represents the first observation of its kind in a PLS-type material.
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Affiliation(s)
- Hangfeng Zhang
- School
of Electronic Engineering and Computer Science, Queen Mary University of London, Mile End Road, LondonE1 4NS, U.K.
| | - A. Dominic Fortes
- STFC
ISIS Facility, Rutherford Appleton Laboratory,Chilton Didcot, OxfordshireOX11 OQX, U.K.
| | - Henry Giddens
- School
of Electronic Engineering and Computer Science, Queen Mary University of London, Mile End Road, LondonE1 4NS, U.K.
| | - Theo Graves Saunders
- School
of Electronic Engineering and Computer Science, Queen Mary University of London, Mile End Road, LondonE1 4NS, U.K.
| | - Matteo Palma
- Department
of Chemistry, Queen Mary University of London, Mile End Road, LondonE1 4NS, U.K.
| | - Isaac Abrahams
- Department
of Chemistry, Queen Mary University of London, Mile End Road, LondonE1 4NS, U.K.,. Tel: +44 207 882 3235
| | - Haixue Yan
- School
of Engineering and Materials Science, Queen
Mary University of London, Mile End Road, LondonE1 4NS, U.K.,. Tel: +44 207 882 5164
| | - Yang Hao
- School
of Electronic Engineering and Computer Science, Queen Mary University of London, Mile End Road, LondonE1 4NS, U.K.,. Tel: +44 207 882 5341
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8
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Cao Y, Xu Y, Li Q, Rose RS, Abrahams I, Jones CR, Sheriff TS. Corrosion Inhibition and Disinfection of Heating and Cooling Water Systems Using In Situ Generated Hydrogen Peroxide. NEW J CHEM 2022. [DOI: 10.1039/d2nj03806d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Aqueous solutions of MnCl2·4H2O and Tiron (disodium 4,5-dihydroxy-1,3-benzenedisulfonate) rapidly remove dioxygen (O2) from aqueous solution at a rate of ~20 mg∙ L -1 min-1 with turnover frequencies (TOFs) of up...
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9
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Yue Y, Xu X, Zhang M, Yan Z, Koval V, Whiteley RM, Zhang D, Palma M, Abrahams I, Yan H. Grain Size Effects in Mn-Modified 0.67BiFeO 3-0.33BaTiO 3 Ceramics. ACS Appl Mater Interfaces 2021; 13:57548-57559. [PMID: 34842408 DOI: 10.1021/acsami.1c16083] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Grain size can have significant effects on the properties of electroceramics for dielectric, piezoelectric, and ferroelectric applications. Here, we systematically investigate the effect of grain size on the structure and properties of Mn-modified 0.67BiFeO3-0.33BaTiO3 ceramics, an important lead-free piezoelectric ceramic that exhibits both a high piezoelectric coefficient and a high Curie point. Ceramics with average grain sizes ranging from 0.46 to 6.85 μm were prepared using conventional and spark plasma sintering. It was found that the morphotropic phase boundary compositions are composed of two polar structures, rhombohedral and tetragonal, with DC poling inducing an increase in the fraction of the rhombohedral phase. All ceramics show relaxor behavior and their freezing temperature moves to higher temperatures with increasing grain size, although their Burns temperature is independent of grain size. In fine-grained ceramics, which show pronounced relaxor behavior, significant grain size dependency is seen in dielectric, piezoelectric, and ferroelectric properties, which is attributed to the presence of single ferroelectric domains and high concentrations of polar nanoregions. In coarse-grained ceramics, a critical grain size of 2.83 μm yields the highest dielectric permittivity at room temperature, with the piezoelectric coefficient plateauing at this grain size, which can be attributed to the contribution of both polar nanoregions and high domain wall density.
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Affiliation(s)
- Yajun Yue
- Department of Chemistry, Queen Mary University of London, Mile End Road, London E1 4NS, U.K
| | - Xinzhao Xu
- Department of Chemistry, Queen Mary University of London, Mile End Road, London E1 4NS, U.K
| | - Man Zhang
- School of Engineering and Materials Science, Queen Mary University of London, Mile End Road, London E1 4NS, U.K
| | - Zhongna Yan
- Department of Chemistry, Queen Mary University of London, Mile End Road, London E1 4NS, U.K
- State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083, China
| | - Vladimir Koval
- Institute of Materials Research, Slovak Academy of Sciences, Watsonova 47, 4704001 Kosice, Slovakia
| | - Richard M Whiteley
- School of Engineering and Materials Science, Queen Mary University of London, Mile End Road, London E1 4NS, U.K
| | - Dou Zhang
- State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083, China
| | - Matteo Palma
- Department of Chemistry, Queen Mary University of London, Mile End Road, London E1 4NS, U.K
| | - Isaac Abrahams
- Department of Chemistry, Queen Mary University of London, Mile End Road, London E1 4NS, U.K
| | - Haixue Yan
- School of Engineering and Materials Science, Queen Mary University of London, Mile End Road, London E1 4NS, U.K
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10
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Azhar S, Ahmad KS, Abrahams I, Lin W, Gupta RK, Mazhar M, Ali D. Phyto-inspired Cu/Bi oxide-based nanocomposites: synthesis, characterization, and energy relevant investigation. RSC Adv 2021; 11:30510-30519. [PMID: 35479863 PMCID: PMC9041097 DOI: 10.1039/d1ra05066d] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Accepted: 08/24/2021] [Indexed: 01/25/2023] Open
Abstract
A modified and sustainable approach is reported in this research for the synthesis of a spherical-shaped CuO–Bi2O3 electrode material for electrochemical studies. Aqueous extract derived from the plant Amaranthus viridis L. (Amaranthaceae) (AVL) was used as a reducing agent for morphological control of the synthesis of CuO–Bi2O3 nanocomposites. The modified nanomaterial revealed an average crystal size of 49 ± 2 nm, which matches very well with scanning electron microscopy (SEM) findings. Furthermore, the synthesized material was characterized using Fourier-transform infrared spectroscopy, field emission SEM and energy-dispersive spectroscopy. The optical band gap energy of 3.45 eV was calculated using a Tauc plot. Finally, the bioorganic framework-derived CuO–Bi2O3 electrode was tested for energy generating and storage applications and the results revealed a capacitance of 389 F g−1 by cyclic voltammetry, with a maximum energy density of 12 W h kg−1 and power density of 5 kW kg−1. Hydrogen evolution reaction and oxygen evolution reaction studies showed good potential of CuO–Bi2O3 as an electrocatalyst for water splitting, with maximum efficiency of the electrode up to 16.5 hours. Spherical-shaped CuO–Bi2O3 electrode material and its electrochemical studies.![]()
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Affiliation(s)
- Sundus Azhar
- Department of Environmental Sciences, Fatima Jinnah Women University Rawalpindi Pakistan
| | - Khuram Shahzad Ahmad
- Department of Environmental Sciences, Fatima Jinnah Women University Rawalpindi Pakistan
| | - Isaac Abrahams
- School of Biological and Chemical Sciences, Queen Mary University of London London UK
| | - Wang Lin
- Department of Chemistry, Pittsburg State University Pittsburg KS 66762 USA
| | - Ram K Gupta
- Department of Chemistry, Pittsburg State University Pittsburg KS 66762 USA
| | - Muhammad Mazhar
- Department of Chemistry, School of Natural Sciences, National University of Sciences and Technology H12 Islamabad Pakistan
| | - Daoud Ali
- Department of Zoology, College of Science, King Saud University PO Box 2455 Riyadh 11451 Saudi Arabia
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11
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Yu C, Viola G, Zhang D, Stroscio Z, Hu Z, Eskilla VR, Grasso S, Wilson RM, Zhou K, Bonini N, Fortes AD, Abrahams I, Yan H. Structural Evolution in BiNbO 4. Inorg Chem 2021; 60:8507-8518. [PMID: 34060816 DOI: 10.1021/acs.inorgchem.1c00149] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The sequence of transitions between different phases of BiNbO4 has been thoroughly investigated and clarified using thermal analysis, high-resolution neutron diffraction, and Raman spectroscopy. The theoretical optical phonon modes of the α-phase have been calculated. Based on thermoanalytical data supported by density functional theory (DFT) calculations, the β-phase is proposed to be metastable, while the α- and γ-phases are stable below and above 1040 °C, respectively. Accurate positional parameters for oxygen positions in the three main polymorphs (α, β, and γ) are presented and the structural relationships between these polymorphs are discussed. Even though no significant changes, only relaxation phenomena, are observed in the dielectric behavior of α-BiNbO4 below 1000 °C, evidence of two further subtle transitions at ∼350 and 600 °C is presented through careful analysis of structural parameters from variable temperature neutron diffraction measurements. Such phase variations are also evident in the phonon modes in Raman spectra and supported by changes in the thermoanalytical data. These subtle transitions may correspond to the previously proposed antiferroelectric to ferroelectric and ferroelectric to paraelectric phase transitions, respectively.
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Affiliation(s)
- Chuying Yu
- School of Engineering and Materials Science, Queen Mary University of London, Mile End Road, London E1 4NS, United Kingdom.,College of Materials Science and Engineering, Hunan University, Changsha, 410082, China
| | - Giuseppe Viola
- Institute for Materials Discovery, University College London (UCL), London WC1E 7JE, United Kingdom
| | - Dou Zhang
- State Key Laboratory of Powder Metallurgy, Central South University, Changsha, 410083, People's Republic of China
| | - Zaira Stroscio
- School of Engineering and Materials Science, Queen Mary University of London, Mile End Road, London E1 4NS, United Kingdom
| | - Zimeng Hu
- School of Engineering and Materials Science, Queen Mary University of London, Mile End Road, London E1 4NS, United Kingdom
| | | | - Salvatore Grasso
- School of Engineering and Materials Science, Queen Mary University of London, Mile End Road, London E1 4NS, United Kingdom.,Key Laboratory of Advanced Technologies of Materials, Ministry of Education, School of Materials Science and Engineering, Southwest Jiaotong, Chengdu 610031, Peoples Republic of China
| | - Rory M Wilson
- School of Engineering and Materials Science, Queen Mary University of London, Mile End Road, London E1 4NS, United Kingdom
| | - Kechao Zhou
- State Key Laboratory of Powder Metallurgy, Central South University, Changsha, 410083, People's Republic of China
| | - Nicola Bonini
- Department of Physics, King's College London, Strand, London WC2R 2LS, United Kingdom
| | - A Dominic Fortes
- ISIS Neutron and Muon Spallation Facility, Rutherford Appleton Laboratory, Chilton, Didcot, Oxfordshire, OX11 0QX, United Kingdom
| | - Isaac Abrahams
- Materials Research Institute, School of Biological and Chemical Sciences, Queen Mary University of London, Mile End Road, London E1 4NS, United Kingdom
| | - Haixue Yan
- School of Engineering and Materials Science, Queen Mary University of London, Mile End Road, London E1 4NS, United Kingdom
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12
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Guilbert AAY, Parr ZS, Kreouzis T, Woods DJ, Sprick RS, Abrahams I, Nielsen CB, Zbiri M. Effect of substituting non-polar chains with polar chains on the structural dynamics of small organic molecule and polymer semiconductors. Phys Chem Chem Phys 2021; 23:7462-7471. [PMID: 33876106 DOI: 10.1039/d1cp00670c] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
The processability and optoelectronic properties of organic semiconductors can be tuned and manipulated via chemical design. The substitution of the popular alkyl side chains by oligoethers has recently been successful for applications such as bioelectronic sensors and photocatalytic hydrogen evolution. Beyond the differences in polarity, the carbon-oxygen bond in oligoethers is likely to render the system softer and more prone to dynamical disorder that can be detrimental to charge transport for example. In this context, we use neutron spectroscopy as a master method of probe, in addition to characterisation techniques such as X-ray diffraction, differential scanning calorimetry and polarized optical microscopy to study the effect of the substitution of n-hexyl (Hex) chains by triethylene glycol (TEG) chains on the structural dynamics of two organic semiconducting materials: a phenylene-bithiophene-phenylene (PTTP) small molecule and a fluorene-co-dibenzothiophene (FS) polymer. Counterintuitively, inelastic neutron scattering (INS) reveals a general softening of the modes of PTTP and FS materials with Hex chains, pointing towards an increased dynamical disorder in the Hex-based systems. However, temperature-dependent X-ray and neutron diffraction as well as INS and differential scanning calorimetry evidence an extra reversible transition close to room temperature for PTTP with TEG chains. The observed extra structural transition, which is not accompanied by a change in birefringence, can also be observed by quasi-elastic neutron scattering (QENS). A fastening of the TEG chains dynamics is observed in the case of PTTP and not FS. We therefore assign this transition to the melt of the TEG chains. Overall the TEG chains are promoting dynamical order at room temperature, but if crystallising, may introduce an extra reversible structural transition above room temperature leading to thermal instabilities. Ultimately, a deeper understanding of chain polarity and structural dynamics can help guide new materials design and navigate the intricate balance between electronic charge transport and aqueous swelling that is being sought for a number of emerging organic electronic and bioelectronic applications.
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Affiliation(s)
- Anne A Y Guilbert
- Department of Physics and Centre for Plastic Electronics, Imperial College London, Prince Consort Road, London SW7 2AZ, UK.
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13
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Zhang M, Chen Z, Yue Y, Chen T, Yan Z, Jiang Q, Yang B, Eriksson M, Tang J, Zhang D, Shen Z, Abrahams I, Yan H. Terahertz Reading of Ferroelectric Domain Wall Dielectric Switching. ACS Appl Mater Interfaces 2021; 13:12622-12628. [PMID: 33685119 DOI: 10.1021/acsami.1c00523] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Ferroelectric domain walls (DWs) are important nanoscale interfaces between two domains. It is widely accepted that ferroelectric domain walls work idly at terahertz (THz) frequencies, consequently discouraging efforts to engineer the domain walls to create new applications that utilize THz radiation. However, the present work clearly demonstrates the activity of domain walls at THz frequencies in a lead-free Aurivillius phase ferroelectric ceramic, Ca0.99Rb0.005Ce0.005Bi2Nb2O9, examined using THz-time-domain spectroscopy (THz-TDS). The dynamics of domain walls are different at kHz and THz frequencies. At low frequencies, domain walls work as a group to increase dielectric permittivity. At THz frequencies, the defective nature of domain walls serves to lower the overall dielectric permittivity. This is evidenced by higher dielectric permittivity in the THz band after poling, reflecting decreased domain wall density. An elastic vibrational model has also been used to verify that a single frustrated dipole in a domain wall represents a weaker contribution to the permittivity than its counterpart within a domain. The work represents a fundamental breakthrough in understanding the dielectric contributions of domain walls at THz frequencies. It also demonstrates that THz probing can be used to read domain wall dielectric switching.
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Affiliation(s)
- Man Zhang
- School of Engineering and Materials Science, Queen Mary University of London, Mile End Road, London E1 4NS, United Kingdom
| | - Zhe Chen
- Faculty of Science and Engineering, University of Chester, Thornton Science Park, Chester CH2 4NU, United Kingdom
- College of Electronic Information Engineering, South-Central University for Nationalities, Minyuan Road, Wuhan 430074, China
| | - Yajun Yue
- School of Biological and Chemical Sciences, Queen Mary University of London, Mile End Road, London E1 4NS, United Kingdom
| | - Tao Chen
- School of Biological and Chemical Sciences, Queen Mary University of London, Mile End Road, London E1 4NS, United Kingdom
| | - Zhongna Yan
- School of Biological and Chemical Sciences, Queen Mary University of London, Mile End Road, London E1 4NS, United Kingdom
- State Key Laboratory of Powder Metallurgy, Central South University, South Lushan Road, Changsha 410083, China
| | - Qinghui Jiang
- School of Materials Science and Engineering, Huazhong University of Science and Technology, Luoyu Road, Wuhan 430074, China
| | - Bin Yang
- Faculty of Science and Engineering, University of Chester, Thornton Science Park, Chester CH2 4NU, United Kingdom
| | - Mirva Eriksson
- Department of Materials and Environmental Chemistry, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Jianhua Tang
- Cancer Research UK Manchester Institute, The University of Manchester, Oxford Road, Manchester SK10 4TG, United Kingdom
| | - Dou Zhang
- State Key Laboratory of Powder Metallurgy, Central South University, South Lushan Road, Changsha 410083, China
| | - Zhijian Shen
- Department of Materials and Environmental Chemistry, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Isaac Abrahams
- School of Biological and Chemical Sciences, Queen Mary University of London, Mile End Road, London E1 4NS, United Kingdom
| | - Haixue Yan
- School of Engineering and Materials Science, Queen Mary University of London, Mile End Road, London E1 4NS, United Kingdom
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14
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Mikhaylovskaya ZA, Abrahams I, Petrova SA, Buyanova E, Tarakina NV, Piankova DV, Morozova MV. Structural, photocatalytic and electroconductive properties of bismuth-substituted CaMoO4. J SOLID STATE CHEM 2020. [DOI: 10.1016/j.jssc.2020.121627] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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15
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Zhang J, Guo Q, Li X, Li C, Wu K, Abrahams I, Yan H, Knight MM, Humphreys CJ, Su L. Solution-Processed Epitaxial Growth of Arbitrary Surface Nanopatterns on Hybrid Perovskite Monocrystalline Thin Films. ACS Nano 2020; 14:11029-11039. [PMID: 32852190 DOI: 10.1021/acsnano.9b08553] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Semiconductor surface patterning at the nanometer scale is crucial for high-performance optical, electronic, and photovoltaic devices. To date, surface nanostructures on organic-inorganic single-crystal perovskites have been achieved mainly through destructive methods such as electron-beam lithography and focused ion beam milling. Here, we present a solution-based epitaxial growth method for creating nanopatterns on the surface of perovskite monocrystalline thin films. We show that high-quality monocrystalline arbitrary nanopatterns can form in solution with a low-cost simple setup. We also demonstrate controllable photoluminescence from nanopatterned perovskite surfaces by adjusting the nanopattern parameters. A seven-fold enhancement in photoluminescence intensity and a three-time reduction of the surface radiative recombination lifetime are observed at room temperature for nanopatterned MAPbBr3 monocrystalline thin films. Our findings are promising for the cost-effective fabrication of monocrystalline perovskite on-chip electronic and photonic circuits down to the nanometer scale with finely tunable optoelectronic properties.
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Affiliation(s)
- Jinshuai Zhang
- School of Engineering and Materials Science, Queen Mary University of London, Mile End Road, London E1 4NS, United Kingdom
| | - Qin Guo
- School of Engineering and Materials Science, Queen Mary University of London, Mile End Road, London E1 4NS, United Kingdom
| | - Xuan Li
- School of Engineering and Materials Science, Queen Mary University of London, Mile End Road, London E1 4NS, United Kingdom
| | - Chao Li
- State Key Laboratory of Advanced Optical Communication Systems and Networks, Department of Electronic Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Kan Wu
- State Key Laboratory of Advanced Optical Communication Systems and Networks, Department of Electronic Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Isaac Abrahams
- School of Biological and Chemical Sciences, Queen Mary University of London, Mile End Road, London E1 4NS, United Kingdom
| | - Haixue Yan
- School of Engineering and Materials Science, Queen Mary University of London, Mile End Road, London E1 4NS, United Kingdom
| | - Martin M Knight
- School of Engineering and Materials Science, Queen Mary University of London, Mile End Road, London E1 4NS, United Kingdom
| | - Colin J Humphreys
- School of Engineering and Materials Science, Queen Mary University of London, Mile End Road, London E1 4NS, United Kingdom
| | - Lei Su
- School of Engineering and Materials Science, Queen Mary University of London, Mile End Road, London E1 4NS, United Kingdom
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16
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Fröhlich K, Abrahams I, Jahn M. Determining phase transitions of layered oxides via electrochemical and crystallographic analysis. Sci Technol Adv Mater 2020; 21:653-660. [PMID: 33061838 PMCID: PMC7534273 DOI: 10.1080/14686996.2020.1814116] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2020] [Revised: 08/20/2020] [Accepted: 08/20/2020] [Indexed: 05/28/2023]
Abstract
The chemical diffusion coefficient in LiNi1/3Mn1/3Co1/3O2 was determined via the galvanostatic intermittent titration technique in the voltage range 3 to 4.2 V. Calculated diffusion coefficients in these layered oxide cathodes during charging and discharging reach a minimum at the open-circuit voltage of 3.8 V and 3.7 V vs. Li/Li+, respectively. The observed minima of the chemical diffusion coefficients indicate a phase transition in this voltage range. The unit cell parameters of LiNi1/3Mn1/3Co1/3O2 cathodes were determined at different lithiation states using ex situ crystallographic analysis. It was shown that the unit cell parameter variation correlates well with the observed values for chemical diffusion in NMC cathodes; with a notable change in absolute values in the same voltage range. We relate the observed variation in unit cell parameters to the nickel conversion into the trivalent state, which is Jahn-Teller active, and to the re-arrangement of lithium ions and vacancies.
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Affiliation(s)
- Katja Fröhlich
- Electric Drive Technology, AIT Austrian Institute of Technology GmbH, Vienna, Austria
| | - Isaac Abrahams
- School of Biological and Chemical Sciences, Queen Mary University of London, London, UK
| | - Marcus Jahn
- Electric Drive Technology, AIT Austrian Institute of Technology GmbH, Vienna, Austria
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17
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Zhang H, Giddens H, Yue Y, Xu X, Araullo-Peters V, Koval V, Palma M, Abrahams I, Yan H, Hao Y. Polar nano-clusters in nominally paraelectric ceramics demonstrating high microwave tunability for wireless communication. Ann Ital Chir 2020. [DOI: 10.1016/j.jeurceramsoc.2020.04.015] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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18
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Liu T, Abrahams I, Dennis TJS. Conformational Analysis of [60]PCBM via Second-Order Proton NMR Spin-Spin Coupling Effects. J Phys Chem Lett 2020; 11:5397-5401. [PMID: 32551707 DOI: 10.1021/acs.jpclett.0c01421] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The 1H NMR spectrum of phenyl C61 butyric acid methyl ester ([60]PCBM) was recorded at high resolution (600 MHz). All of the 1H resonances expected of the Cs-symmetric molecule were observed. The spin-spin couplings in the 1H NMR spectrum were not as expected at first order. Instead, the effects of AA'BB'-type second-order couplings were clearly observed for the protons attached to both ester carbons C3 and C4, which were analyzed in terms of seven coupling constants. This indicates that there is no free rotation of the σ bonds of the alkyl chain in the ester group, although rotation becomes free at a larger distance from the fullerene bridge carbon (C61). The 1H NMR results further indicated that there is a 1:6:1 population ratio of the three staggered conformers (gauche:anti:gauche') about the ester group C3-C4 bond. These results may aid in the understanding of the morphological interactions between [60]PCBM and its surroundings in condensed-phase organic electronic devices such as organic and perovskite photovoltaics.
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Affiliation(s)
- Tong Liu
- School of Physics and Astronomy, Queen Mary University of London, Mile End Road, London E1 4NS, U.K
| | - Isaac Abrahams
- School of Biological and Chemical Sciences, Queen Mary University of London, Mile End Road, London E1 4NS, U.K
| | - T John S Dennis
- School of Physics and Astronomy, Queen Mary University of London, Mile End Road, London E1 4NS, U.K
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19
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Foroutan F, Kyffin BA, Abrahams I, Knowles JC, Sogne E, Falqui A, Carta D. Mesoporous Strontium-Doped Phosphate-Based Sol-Gel Glasses for Biomedical Applications. Front Chem 2020; 8:249. [PMID: 32391313 PMCID: PMC7191082 DOI: 10.3389/fchem.2020.00249] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2020] [Accepted: 03/16/2020] [Indexed: 12/17/2022] Open
Abstract
Mesoporous phosphate-based glasses have great potential as biomedical materials being able to simultaneously induce tissue regeneration and controlled release of therapeutic molecules. In the present study, a series of mesoporous phosphate-based glasses in the P2O5-CaO-Na2O system, doped with 1, 3, and 5 mol% of Sr2+, were prepared using the sol-gel method combined with supramolecular templating. A sample without strontium addition was prepared for comparison. The non-ionic triblock copolymer EO20PO70EO20 (P123) was used as a templating agent. Scanning electron microscopy (SEM) images revealed that all synthesized glasses have an extended porous structure. This was confirmed by N2 adsorption-desorption analysis at 77 K that shows a porosity typical of mesoporous materials. 31P magic angle spinning nuclear magnetic resonance (31P MAS-NMR) and Fourier transform infrared (FTIR) spectroscopies have shown that the glasses are mainly formed by Q1 and Q2 phosphate groups. Degradation of the glasses in deionized water assessed over a 7-day period shows that phosphate, Ca2+, Na+, and Sr2+ ions can be released in a controlled manner over time. In particular, a direct correlation between strontium content and degradation rate was observed. This study shows that Sr-doped mesoporous phosphate-based glasses have great potential in bone tissue regeneration as materials for controlled delivery of therapeutic ions.
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Affiliation(s)
- Farzad Foroutan
- Department of Chemistry, University of Surrey, Guildford, United Kingdom
| | | | - Isaac Abrahams
- School of Biological and Chemical Sciences, Materials Research Institute, Queen Mary University of London, London, United Kingdom
| | - Jonathan C. Knowles
- Division of Biomaterials and Tissue Engineering, University College London, Eastman Dental Institute, London, United Kingdom
- The Discoveries Centre for Regenerative and Precision Medicine, London, United Kingdom
- Department of Nanobiomedical Science & BK21 PLUS NBM Global Research Centre for Regenerative Medicine, Dankook University, Cheonan-si, South Korea
- UCL Eastman-Korea Dental Medicine Innovation Centre, Dankook University, Cheonan-si, South Korea
| | - Elisa Sogne
- NABLA Lab, Biological and Environmental Sciences and Engineering (BESE) Division, King Abdullah University of Science and Technology (KAUST), Thuwal, Saudi Arabia
| | - Andrea Falqui
- NABLA Lab, Biological and Environmental Sciences and Engineering (BESE) Division, King Abdullah University of Science and Technology (KAUST), Thuwal, Saudi Arabia
| | - Daniela Carta
- Department of Chemistry, University of Surrey, Guildford, United Kingdom
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Foroutan F, Kyffin BA, Abrahams I, Corrias A, Gupta P, Velliou E, Knowles JC, Carta D. Mesoporous Phosphate-Based Glasses Prepared via Sol–Gel. ACS Biomater Sci Eng 2020; 6:1428-1437. [DOI: 10.1021/acsbiomaterials.9b01896] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Farzad Foroutan
- Department of Chemistry, University of Surrey, Guildford GU2 7XH, U.K
| | | | - Isaac Abrahams
- Materials Research Institute, School of Biological and Chemical Sciences, Queen Mary University of London, Mile End Road, London E1 4NS, U.K
| | - Anna Corrias
- School of Physical Sciences, University of Kent, Canterbury CT2 7NH, U.K
| | - Priyanka Gupta
- Department of Chemical and Process Engineering, Bioprocess and Biochemical Engineering group (BioProChem), University of Surrey, Guildford GU2 7XH, U.K
| | - Eirini Velliou
- Department of Chemical and Process Engineering, Bioprocess and Biochemical Engineering group (BioProChem), University of Surrey, Guildford GU2 7XH, U.K
| | - Jonathan C. Knowles
- Division of Biomaterials and Tissue Engineering, University College London, Eastman Dental Institute, 256 Gray’s Inn Road, London WC1X 8LD, U.K
- The Discoveries Centre for Regenerative and Precision Medicine, University College London Campus, London WC1E 6BT, U.K
- Department of Nanobiomedical Science & BK21 PLUS NBM Global Research Center for Regenerative Medicine, Dankook University, Cheonan 31114, Republic of Korea
- UCL Eastman-Korea Dental Medicine Innovation Centre, Dankook University, Cheonan 31114, Republic of Korea
| | - Daniela Carta
- Department of Chemistry, University of Surrey, Guildford GU2 7XH, U.K
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21
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Yue Y, Cao Z, Yang F, Wang J, Abrahams I. Preparation of an Anti‐Aggregation Silica/Zinc/Graphene Oxide Nanocomposite with Enhanced Adsorption Capacity. Chemistry 2019; 25:16340-16349. [DOI: 10.1002/chem.201903875] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2019] [Indexed: 12/12/2022]
Affiliation(s)
- Yajun Yue
- College of Chemistry and Chemical EngineeringCentral South University Changsha 410083 P. R. China
- Materials Research InstituteSchool of Biological and Chemical SciencesQueen Mary University of London London E1 4NS UK
| | - Zhanfang Cao
- College of Chemistry and Chemical EngineeringCentral South University Changsha 410083 P. R. China
| | - Fan Yang
- College of Chemistry and Chemical EngineeringCentral South University Changsha 410083 P. R. China
| | - Jing Wang
- College of Chemistry and Chemical EngineeringCentral South University Changsha 410083 P. R. China
| | - Isaac Abrahams
- Materials Research InstituteSchool of Biological and Chemical SciencesQueen Mary University of London London E1 4NS UK
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22
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Borowska-Centkowska A, Liu X, Krynski M, Leszczynska M, Wrobel W, Malys M, Hull S, Norberg ST, Krok F, Abrahams I. Defect structure in δ-Bi 5PbY 2O 11.5. RSC Adv 2019; 9:9640-9653. [PMID: 35520691 PMCID: PMC9062157 DOI: 10.1039/c9ra01233h] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2019] [Accepted: 03/13/2019] [Indexed: 11/26/2022] Open
Abstract
A detailed study of the defect structure in a di-substituted δ-Bi2O3 type phase, δ-Bi5PbY2O11.5, is presented. Using a combination of conventional Rietveld analysis of neutron diffraction data, reverse Monte Carlo (RMC) analysis of total neutron scattering data and ab initio molecular dynamics (MD) simulations, both average and local structures have been characterized. δ-Bi5PbY2O11.5 represents a model system for the highly conducting δ-Bi2O3 type phases, in which there is a higher nominal vacancy concentration than in the unsubstituted parent compound. Uniquely, the methodology developed in this study has afforded the opportunity to study both oxide-ion vacancy ordering as well as specific cation–cation interactions. Oxide-ion vacancies in this system have been found to show a preference for association with Pb2+ cations, with some evidence for clustering of these cations. The system shows a non-random distribution of vacancy pair alignments, with a preference for 〈100〉 ordering, the extent of which shows thermal variation. MD simulations indicate a predominance of oxide-ion jumps in the 〈100〉 direction. Total neutron scattering analysis and ab initio MD simulations reveal details of oxide ion vacancy ordering and migration pathways.![]()
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Affiliation(s)
| | - Xi Liu
- Materials Research Institute
- School of Biological and Chemical Sciences
- Queen Mary University of London
- London E1 4NS
- UK
| | - Marcin Krynski
- Faculty of Physics
- Warsaw University of Technology
- 00-662 Warszawa
- Poland
| | | | - Wojciech Wrobel
- Faculty of Physics
- Warsaw University of Technology
- 00-662 Warszawa
- Poland
| | - Marcin Malys
- Faculty of Physics
- Warsaw University of Technology
- 00-662 Warszawa
- Poland
| | - Stephen Hull
- ISIS Facility
- Rutherford Appleton Laboratory
- Oxon OX11 0QX
- UK
| | - Stefan T. Norberg
- Chalmers University of Technology
- Department of Chemistry and Chemical Engineering
- SE-41296 Gothenburg
- Sweden
| | - Franciszek Krok
- Faculty of Physics
- Warsaw University of Technology
- 00-662 Warszawa
- Poland
| | - Isaac Abrahams
- Materials Research Institute
- School of Biological and Chemical Sciences
- Queen Mary University of London
- London E1 4NS
- UK
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23
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Robben L, Abrahams I, Fischer M, Hull S, Dove MT, Gesing TM. Low-temperature anharmonicity and symmetry breaking in the sodalite |Na8I2|[AlSiO4]6. Z KRIST-CRYST MATER 2018. [DOI: 10.1515/zkri-2018-2122] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Abstract
The aluminosilicate iodide sodalite |Na8I2|[AlSiO4]6 was examined by temperature-dependent neutron time-of-flight powder diffraction from 5 K to 290 K and X-ray diffraction from 298 K to 1200 K. The temperature-dependent properties of the mean structure in space group P4̅3n were obtained by Rietveld analysis. A negative slope for the thermal expansion coefficient below 50 K could be observed, and the displacement parameters of the iodide ions indicate anharmonic effects. Local structure models (8×8×8 super cells) were refined against pair-distribution functions calculated from total scattering data collected at 5 K, 165 K and 240 K. The results indicate isotropic displacements for all atoms except for I-atoms, showing the effects of an anharmonic potential around this anion at very low temperatures.
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Affiliation(s)
- Lars Robben
- University of Bremen, Institute for Inorganic Chemistry and Crystallography , Leobener Str. 7 , D-28359 Bremen , Germany
- University of Bremen, MAPEX Centre for Materials and Processes , Bibliothekstrasse 1 , D-28359 Bremen , Germany
| | - Isaac Abrahams
- School of Biological and Chemical Sciences, Queen Mary University of London , Mile End Road , London E1 4NS , UK
| | - Michael Fischer
- University of Bremen, Crystallography Group , Department of Geosciences , Klagenfurter Str. 2-4 , 28359 Bremen , Germany
| | - Stephen Hull
- ISIS Facility , Rutherford Appleton Laboratory , Chilton, Didcot, Oxfordshire OX11 0QX , UK
| | - Martin T. Dove
- School of Physics and Astronomy, Queen Mary University of London , Mile End Road , London E1 4NS , UK
| | - Thorsten M. Gesing
- University of Bremen, Institute for Inorganic Chemistry and Crystallography , Leobener Str. 7 , D-28359 Bremen , Germany
- University of Bremen, MAPEX Centre for Materials and Processes , Bibliothekstrasse 1 , D-28359 Bremen , Germany
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24
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Liu T, Abrahams I, Dennis TJS. Structural Identification of 19 Purified Isomers of the OPV Acceptor Material bisPCBM by 13C NMR and UV-Vis Absorption Spectroscopy and High-Performance Liquid Chromatography. J Phys Chem A 2018; 122:4138-4152. [PMID: 29498855 DOI: 10.1021/acs.jpca.8b00713] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The molecular structures of 19 purified isomers of bis-phenyl-C62-butyric acid methyl ester were identified by a combination of 13C NMR and UV-vis absorption spectroscopies and high-performance liquid chromatography (HPLC) retention time analysis. All 19 isomers are dicyclopropafullerenes (none are homofullerenes). There were seven isomers with C1 molecular point-group symmetry, four with C s, six with C2, one with C2 v, and one with C2 h symmetry. The C2 h, C2 v, and all five nonequatorial C1 isomers were unambiguously assigned to their respective HPLC fractions. For the other 12 isomers, the 13C NMR and UV-vis spectra placed them in six groups of two same-symmetry isomers. On the basis of the widely spaced HPLC retention times of the two isomers within each of these six groups, and the empirical inverse correlation between retention time and addend spacing, each isomer was assigned to its corresponding HPLC fraction. In addition, the missing trans-1 isomer was found, purified, and characterized.
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25
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Yu C, Viola G, Zhang D, Zhou K, Koval V, Mahajan A, Wilson RM, Tarakina NV, Abrahams I, Yan H. Phase evolution and electrical behaviour of samarium-substituted bismuth ferrite ceramics. Ann Ital Chir 2018. [DOI: 10.1016/j.jeurceramsoc.2017.12.016] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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26
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Kanwal N, Toms H, Hannon AC, Perras FA, Bryce DL, Karpukhina N, Abrahams I. Structure and solubility behaviour of zinc containing phosphate glasses. J Mater Chem B 2015; 3:8842-8855. [PMID: 32263478 DOI: 10.1039/c4tb01504e] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The structure of phosphate glasses of general composition 10Na2O : (20 + x/2)ZnO : (20 + x/2)CaO : (50 -x)P2O5 (0 ≤x≤ 20) has been investigated using IR spectroscopy, 1D 31P and 43Ca MAS Bloch decay, 31P-31P double quantum MAS-NMR and 43Ca and 67Zn static NMR techniques, as well as neutron diffraction analysis. Zinc is shown to aid glass formation in this system. Glass transition temperature and density increase with increasing cation : phosphate ratio. However, free volume calculations show structures becoming significantly more compact from x = 5 to x = 10. The structural data confirm depolymerisation of the glasses with increasing cation : phosphate ratio. Zinc oxide is found to act in a network forming role in the system, with 67Zn NMR and neutron diffraction analysis confirming zinc exhibits predominantly four-coordinate geometry. Solubility in deionised water and tris/HCl buffer solution is seen to decrease significantly with increasing x-value. This is discussed in terms of water ingress and the degree of structural openness, associated with increased cross-linking and a decrease in concentration of P-O-P linkages. pH measurements confirm invert phosphate compositions maintain physiological pH levels on immersion in water and buffer solutions for up to four weeks.
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Affiliation(s)
- N Kanwal
- Materials, Research Institute, School of Biological and Chemical Sciences, Queen Mary University of London, Mile End Road, London E1 4NS, UK.
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27
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García-Saiz A, de Pedro I, Vallcorba O, Migowski P, Hernández I, Fernández Barquin L, Abrahams I, Motevalli M, Dupont J, Gonzalez JA, Fernández JR. 1-Ethyl-2,3-dimethylimidazolium paramagnetic ionic liquids with 3D magnetic ordering in its solid state: synthesis, structure and magneto-structural correlations. RSC Adv 2015. [DOI: 10.1039/c5ra05723j] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
We present two novel paramagnetic ionic liquids, Edimim FeX4 (X = Cl and Br), which display a three-dimensional magnetic ordering below 10 K. Exhaustive and systematic studies of the magneto-structural correlations have been performed.
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Affiliation(s)
- Abel García-Saiz
- CITIMAC
- Facultad de Ciencias
- Universidad de Cantabria
- Santander 39005
- Spain
| | - Imanol de Pedro
- CITIMAC
- Facultad de Ciencias
- Universidad de Cantabria
- Santander 39005
- Spain
| | | | - Pedro Migowski
- Universidade Federal do Rio Grande do Sul
- Porto Alegre
- Brazil
| | - Ignacio Hernández
- CITIMAC
- Facultad de Ciencias
- Universidad de Cantabria
- Santander 39005
- Spain
| | | | - Isaac Abrahams
- Materials Research Institute
- Department of Chemistry and Biochemistry
- School of Biological and Chemical Sciences
- Queen Mary University of London
- London E1 4NS
| | - Majid Motevalli
- Materials Research Institute
- Department of Chemistry and Biochemistry
- School of Biological and Chemical Sciences
- Queen Mary University of London
- London E1 4NS
| | - Jairton Dupont
- Universidade Federal do Rio Grande do Sul
- Porto Alegre
- Brazil
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28
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Abstract
Ab initio molecular dynamics calculations show low energy barriers for oxide ion conduction along c-axis channels in βIII-Bi14YO22.5.
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Affiliation(s)
- M. Struzik
- Faculty of Physics
- Warsaw University of Technology
- 00-662 Warszawa
- Poland
| | - M. Malys
- Faculty of Physics
- Warsaw University of Technology
- 00-662 Warszawa
- Poland
| | - M. Krynski
- Faculty of Physics
- Warsaw University of Technology
- 00-662 Warszawa
- Poland
| | - M. Wojcik
- Faculty of Physics
- Warsaw University of Technology
- 00-662 Warszawa
- Poland
| | - J. R. Dygas
- Faculty of Physics
- Warsaw University of Technology
- 00-662 Warszawa
- Poland
| | - W. Wrobel
- Faculty of Physics
- Warsaw University of Technology
- 00-662 Warszawa
- Poland
| | - F. Krok
- Faculty of Physics
- Warsaw University of Technology
- 00-662 Warszawa
- Poland
| | - I. Abrahams
- Materials Research Institute
- Department of Chemistry and Biochemistry
- School of Biological and Chemical Sciences
- Queen Mary University of London
- London E1 4NS
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29
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Leszczynska M, Liu X, Wrobel W, Malys M, Norberg ST, Hull S, Krok F, Abrahams I. Total scattering analysis of cation coordination and vacancy pair distribution in Yb substituted δ-Bi2O3. J Phys Condens Matter 2013; 25:454207. [PMID: 24141081 DOI: 10.1088/0953-8984/25/45/454207] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Reverse Monte Carlo (RMC) modelling of neutron total scattering data, combined with conventional Rietveld analysis of x-ray and neutron data, has been used to describe the cation coordination environments and vacancy pair distribution in the oxide ion conducting electrolyte Bi3YbO6. The thermal variation of the cubic fluorite unit cell volume, monitored by variable temperature x-ray and neutron experiments, reveals significant curvature, which is explained by changes in the oxide ion distribution. There is a significant increase in tetrahedral oxide ion vacancy concentration relative to δ-Bi2O3, due to the creation of Frenkel defects associated with the Yb(3+) cation. The tetrahedral oxide ion vacancy concentration increases from room temperature to 800 °C, but little change is observed in the vacancy pair distribution with temperature. The vacancy pair distributions at both temperatures are consistent with a favouring of [100] vacancy pairs.
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Affiliation(s)
- M Leszczynska
- Faculty of Physics, Warsaw University of Technology, Koszykowa 75, 00-662 Warszawa, Poland
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30
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Holdynski M, Sintyureva M, Liu X, Wrobel W, Dygas JR, Pisarek M, Nix RM, Krok F, Abrahams I. Phase and electrical behaviour in Bi4NbO8.5. J Phys Condens Matter 2012; 24:045904. [PMID: 22214934 DOI: 10.1088/0953-8984/24/4/045904] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
A study of phase and electrical behaviour in the bismuth niobate, Bi(4)NbO(8.5), using x-ray and neutron powder diffraction, thermogravimetric analysis (TGA), x-ray photoelectron spectroscopy (XPS) and ac impedance spectroscopy is presented. Two polymorphs were identified in this composition, a tetragonal phase (type III), which can appear at temperatures above 800 °C and a pseudo-cubic phase (type II) evident at lower temperatures. The defect structure analysis of the type II phase is consistent with the existence of chains of niobate polyhedra, which facilitate electronic conduction at low temperatures. The appearance of the type III phase is strongly dependent on experimental conditions and TGA and XPS measurements suggest a likely association with change in oxygen stoichiometry.
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Affiliation(s)
- M Holdynski
- Institute of Physical Chemistry, Polish Academy of Sciences, Warsaw, Poland.
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31
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Weng X, Knowles JC, Abrahams I, Wu Z, Darr JA. In situ variable temperature X-ray diffraction studies on the transformations of nano-precursors to La–Ni–O phases. J SOLID STATE CHEM 2011. [DOI: 10.1016/j.jssc.2011.04.031] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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32
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Affiliation(s)
- Sonia Pulacchini
- a Department of Chemistry, Queen Mary , University of London , Mile End Road, London , E1 4NS , UK
| | - Isaac Abrahams
- a Department of Chemistry, Queen Mary , University of London , Mile End Road, London , E1 4NS , UK
| | - Jason Eames
- a Department of Chemistry, Queen Mary , University of London , Mile End Road, London , E1 4NS , UK
| | - Michael Watkinson
- a Department of Chemistry, Queen Mary , University of London , Mile End Road, London , E1 4NS , UK
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33
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Pires RA, Abrahams I, Nunes TG, Hawkes GE. The role of alumina in aluminoborosilicate glasses for use in glass–ionomer cements. ACTA ACUST UNITED AC 2009. [DOI: 10.1039/b822285a] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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34
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Abrahams I, Hawkes GE, Ahmed A, Di Cristina T, Demetriou DZ, Ivanova GI. Structures of the chain metaphosphates NaM(PO3)3 (M = Ca or Sr). Magn Reson Chem 2008; 46:316-322. [PMID: 18306173 DOI: 10.1002/mrc.2161] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Solid-state (23)Na and (31)P magic-angle spinning nuclear magnetic resonance spectroscopy and X-ray crystallography have been used to study the structures of the chain metaphosphates NaCa(PO(3))(3) and NaSr(PO(3))(3). The compounds are isostructural and crystallise in space group P(-1) with the following parameters: NaCa(PO(3))(3), a = 6.711 A, b = 6.934 A, c = 7.619 A, alpha = 83.44 degrees , beta = 81.41 degrees , gamma = 82.80 degrees ; NaSr(PO(3))(3)a = 6.805 A, b = 7.133 A, c = 7.720 A and alpha = 83.71 degrees , beta = 80.48 degrees , gamma = 82.87 degrees . Both structures contain anionic metaphosphate chains of (PO(3))(n) (n) with ionic contacts to Na(+) ions in distorted octahedral sites and Ca(2+) (or Sr(2+)) in distorted dodecahedral sites. (31)P and (23)Na NMR are entirely consistent with the crystallographic data and an empirical method for assigning (31)P resonances to particular crystallographically unique P atoms is described.
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Affiliation(s)
- I Abrahams
- Centre for Materials Research, School of Biological and Chemical Sciences, Queen Mary, University of London, Mile End Road London E1, 4NS, UK.
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35
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Zheng Y, Motevalli M, Tan RH, Abrahams I, Gillin WP, Wyatt PB. Near IR luminescent rare earth 3,4,5,6-tetrafluoro-2-nitrophenoxide complexes: Synthesis, X-ray crystallography and spectroscopy. Polyhedron 2008. [DOI: 10.1016/j.poly.2008.01.022] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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36
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Pires RA, Nunes TG, Abrahams I, Hawkes GE. The role of aluminium and silicon in the setting chemistry of glass ionomer cements. J Mater Sci Mater Med 2008; 19:1687-92. [PMID: 17914623 DOI: 10.1007/s10856-007-3251-y] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/22/2007] [Accepted: 07/30/2007] [Indexed: 05/17/2023]
Abstract
A model of the setting chemistry of glass-ionomer cements (GICs) is proposed based on 27Al and 29Si solid state nuclear magnetic resonance spectroscopy data on three GICs. All the precursor glasses are found to contain three aluminium species viz.: four, five and six-coordinate aluminium environments as well as four-bridging silicate tetrahedra. Upon cement formation, Al3+ ions in the glass are leached out from the surface layer of the glass. On entering the cement matrix, these ions adopt six-coordination and crosslink the polymer chains as part of the setting reaction. The remaining four-coordinate aluminium is distributed between two species: one in the inert core of the glass particles; and a second, less concentrated, in the surface layer of the glass particles, modified by the curing reactions. There is some evidence for residual five and six coordinate aluminium species in the final cement in some of the systems. In the case of the silicate tetrahedra, the curing reactions result in a decrease in the number of aluminium atoms in the second coordination sphere, with a subsequent recondensation of silicate network of the glass.
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Affiliation(s)
- Ricardo A Pires
- Departamento de Engenharia de Materiais, Instituto Superior Técnico, Universidade Técnica de Lisboa, Av. Rovisco Pais, 1, Lisboa 1049-001, Portugal.
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37
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Viteva L, Gospodova T, Rashkova J, Abrahams I, Timtcheva I, Simova S, Mazieres MR, Wolf JG. Synthesis and Photophysical Properties of Some Rigidized Hepta- and Nonamethine Mono- and Bis(merocyanines): Ring-Opening of Quaternized 2-Methylbenzothiazole. European J Org Chem 2007. [DOI: 10.1002/ejoc.200700125] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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38
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Tan RHC, Motevalli M, Abrahams I, Wyatt PB, Gillin WP. Quenching of IR luminescence of erbium, neodymium, and ytterbium beta-diketonate complexes by ligand C-H and C-D bonds. J Phys Chem B 2007; 110:24476-9. [PMID: 17134204 DOI: 10.1021/jp0654462] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The effect of CH and CD quenching on the luminescence lifetime of Er(3+) Nd(3+) and Yb(3+) in the Cs[Ln(HFA)(4)] system has been quantified, and we have shown that for Er(3+) ions the quenching is dominated by the nearest neighbor CH oscillators, whereas for Nd(3+) ions the roles of more distant CH oscillators and nearest neighbor CD oscillators are important.
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Affiliation(s)
- Rendy H C Tan
- Department of Physics and School of Biological and Chemical Sciences, Queen Mary, University of London, Mile End Road, London, U.K
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39
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Ubic R, Hu Y, Abrahams I. Neutron and electron diffraction studies of La(Zn1/2Ti1/2)O3 perovskite. Acta Crystallogr B Struct Sci 2006; 62:521-9. [PMID: 16840801 DOI: 10.1107/s0108768106015527] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2005] [Accepted: 04/27/2006] [Indexed: 11/10/2022]
Abstract
The crystallography and microwave dielectric properties of La(Zn1/2Ti1/2)O3 (LZT) ceramics prepared via the mixed-oxide route were investigated in this study. While samples were largely single phase, small amounts of ZnO impurity were detected in sintered pellets. Observed reflections in electron and neutron diffraction patterns indicate that the symmetry of LZT is P21/n. The B site is ordered on {110} or pseudocubic {111}, but the presence of the pseudocubic 1\over2(111) reflection is in itself insufficient to indicate the existence of such order. Rietveld refinements of the neutron diffraction data yield an excellent fit for such a model. The structure is highly twinned, with variants related through common {211} composition planes and 90° rotations about 〈011〉. The microwave dielectric properties measured were ∊
r
= 34, Qf = 36 090 and τ
f
= −70 MK−1.
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Affiliation(s)
- Rick Ubic
- Centre for Materials Research, Queen Mary, University of London, England.
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40
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Abrahams I, Demetriou D, Vordemvenne E, Mustarde K, Benoit D. Lone pair effects in trihalo-stannate and -plumbate anions in the crystal structures of Sr(MX3)2·5H2O (M=Sn, X=Cl, Br; M=Pb, X=Br): A joint crystallographic and electronic structure calculation approach. Polyhedron 2006. [DOI: 10.1016/j.poly.2005.11.023] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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41
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42
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Pires RA, Abrahams I, Nunes TG, Hawkes GE. Multinuclear magnetic resonance studies of borosilicate glasses for use in glass ionomer cements: incorporation of CaO and Al2O3. ACTA ACUST UNITED AC 2006. [DOI: 10.1039/b601593j] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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43
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44
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Silwood CJL, Abrahams I, Apperley DC, Lockyer NP, Lynch E, Motevalli M, Nix RM, Grootveld M. Surface analysis of novel hydroxyapatite bioceramics containing titanium(iv) and fluoride. ACTA ACUST UNITED AC 2005. [DOI: 10.1039/b417539e] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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45
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Simeonova M, Velichkova R, Ivanova G, Enchev V, Abrahams I. Study on the role of 5-fluorouracil in the polymerization of butylcyanoacrylate during the formation of nanoparticles. J Drug Target 2004; 12:49-56. [PMID: 15203911 DOI: 10.1080/1061186042000207011] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
The possible involvement of 5-fluorouracil (5FU) in the initiation process of the polymerization of n-butylcyanoacrylate monomer during nanoparticle formation was investigated. 5FU in acidic solution (pH 2-3) may interfere in the initiation process through its amino groups via the formation of zwitterions. The proposed zwitterionic mechanism of initiation was supported by the molecular weight profiles of the polymer, determined by gel permeation chromatography, and the covalent linkage of the cytostatic to the main polymer chain. H NMR analyses clearly demonstrated that a significant fraction of 5FU was covalently bonded to the poly(butylcyanoacrylate) chains through its amino groups preferentially through one of the two nitrogen atoms. In vitro release study performed shows that the investigated 5FU-loaded PBCN are suitable for sustaining delivery of 5FU.
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Affiliation(s)
- M Simeonova
- Institute of Polymers Bulgarian Academy of Sciences, Acad. G. Bonchev Street, bl. 103A 1113, Sofia, Bulgaria.
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46
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Pires R, Nunes TG, Abrahams I, Hawkes GE, Morais CM, Fernandez C. Stray-field imaging and multinuclear magnetic resonance spectroscopy studies on the setting of a commercial glass-ionomer cement. J Mater Sci Mater Med 2004; 15:201-208. [PMID: 15334991 DOI: 10.1023/b:jmsm.0000015479.65516.d0] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
A commercial glass-ionomer (Fuji II) was studied using different NMR techniques. 1H and 19F stray-field imaging (STRAFI) were used to monitor the curing kinetics of the cement and two processes were distinguished: the gelation and maturation phases. Characterization of the aluminium and silicon species present in the glass component and cement was performed by conventional 27Al and 29Si MAS and two-dimensional 27Al triple quantum MAS NMR (MQMAS) techniques. Quantification of the aluminium in the glass component and in the cement indicates the leaching of about 32% of the 4-coordinate aluminium, about 100% of the 5-coordinate aluminium and about 41% of the 6-coordinate aluminium, during the setting reaction. It is also shown that the 5-coordinate aluminium is only present in the surface layer created by the acid attack during the cement formation process. In the cement, silicon maintains species with four bridging oxygens after the leaching of tetrahedral (4-coordinate) aluminium. The silicon analysis correlates well with the aluminium determinations.
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Affiliation(s)
- Ricardo Pires
- Departamento de Engenharia de Materiais, Instituto Superior Técnico, Universidade Técnica de Lisboa, Av Rovisco Pais, 1, 1049-001 Lisboa, Portugal
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47
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Abstract
Glasses of general formula 50Li(2)O : xSnO(2) : (10 -x)TiO(2) : 40P(2)O(5)(0.0 < or = x < or = 10) were investigated by differential scanning calorimetry, X-ray diffraction and ac impedance, (31)P solid-state NMR and IR spectroscopies. Three isotropic resonances can be identified in the (31)P NMR spectra, which have been assigned to various phosphate species. Analysis of the ratios of integrated intensities in the (31)P spectra leads to models for the Ti and Sn coordination environments. Both TiO(2) and SnO(2) are found to be predominantly network forming with Ti and Sn proposed to be in five- and four-coordinate environments respectively. Analysis of ac impedance spectra collected at low temperatures reveals two forms of permittivity dispersion, viz: high frequency conductivity dispersion and Cole-Cole type relaxation of permittivity. The activation energy of the relaxation frequency of the permittivity dispersion is equal to that of the dc conductivity, which is consistent with cooperative motion of lithium ions. The results also suggest that the observed increase in conductivity with temperature appears to be mainly due to an increase in mobility rather than increase in carrier concentration.
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Affiliation(s)
- Isaac Abrahams
- Centre for Materials Research, Department of Chemistry, University of London, Queen Mary, Mile End Road, London, UK E1 4NS
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48
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Abstract
Poly(butylcyanoacrylate) nanoparticles (PBCN) as a drug carrier of 5-fluorouracil (5FU) intended for topical treatment of skin lesia were investigated. The presence of 5FU (as saline solution, pH 10-11) in the polymerization medium affected the polymerization as well as the nanoparticle formation by influencing the initiation of the polymerization reaction. 5FU acted as an initiator in the anionic polymerization of n-butylcyanoacrylate monomer through its nucleophilic nitrogen centers. The results obtained by GPC, 1H NMR, and X-ray diffraction allude to a possible mechanism of cytostatic immobilization in the polymer matrix, with evidence for both free and bound forms of the drug.
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Affiliation(s)
- M Simeonova
- Laboratory of Amphiphilic and Nonionogenic Polymers, Institute of Polymers, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., bl. 103A, 1113 Sofia, Bulgaria.
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Abrahams I, Krok F. Defect chemistry of the BIMEVOXesElectronic supplementary information (ESI) available: full list of schemes for all combinations of l and CN generated using the program DEFEQN. A listing of the program is also available. See http://www.rsc.org/suppdata/jm/b2/b203992n/. ACTA ACUST UNITED AC 2002. [DOI: 10.1039/b203992n] [Citation(s) in RCA: 82] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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