1
|
Brunner P, Würschum R. Diffusion-reaction model of positron annihilation for complex defect pattern. J Phys Condens Matter 2023; 36:125703. [PMID: 38098320 DOI: 10.1088/1361-648x/ad1279] [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] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/28/2023] [Accepted: 12/05/2023] [Indexed: 02/01/2024]
Abstract
The increasing structural complexity in modern material science is often associated with grain sizes in theµm- and the sub-µm-regime. Therefore, when positron annihilation is applied for studying free-volume type defects in such materials, positron trapping at grain boundaries (GBs) cannot be neglected, even when other defect types are in the primary focus. For this purpose, the available diffusion-reaction model for positron trapping and annihilation at GBs is extended to competitive trapping at two different types of intragranular defects. Closed-form expressions for the mean positron lifetime and the relative intensities of the defect-specific positron lifetime components are given. The model is presented for cylindrical-shaped crystallites, but is valid in the general sense for spherical symmetry as well with appropriate replacements. The model yields the basis for properly determining defect concentrations, even for the inconvenient but common case that one intragranular defect type exhibits a lifetime component similar to that in GBs. It turns out, that positron trapping at GBs matters even forµm-sized crystallites and should not be neglected for precise studies of intragranular defects.
Collapse
Affiliation(s)
- Philipp Brunner
- Institute of Materials Physics, Graz University of Technology, NAWI Graz, Petersgasse 16, Graz A-8010, Austria
| | - Roland Würschum
- Institute of Materials Physics, Graz University of Technology, NAWI Graz, Petersgasse 16, Graz A-8010, Austria
| |
Collapse
|
2
|
Steuer O, Liedke MO, Butterling M, Schwarz D, Schulze J, Li Z, Wagner A, Fischer IA, Hübner R, Zhou S, Helm M, Cuniberti G, Georgiev YM, Prucnal S. Evolution of point defects in pulsed-laser-melted Ge 1-xSn xprobed by positron annihilation lifetime spectroscopy. J Phys Condens Matter 2023; 36:085701. [PMID: 37931296 DOI: 10.1088/1361-648x/ad0a10] [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] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/21/2023] [Accepted: 11/06/2023] [Indexed: 11/08/2023]
Abstract
Direct-band-gap Germanium-Tin alloys (Ge1-xSnx) with high carrier mobilities are promising materials for nano- and optoelectronics. The concentration of open volume defects in the alloy, such as Sn and Ge vacancies, influences the final device performance. In this article, we present an evaluation of the point defects in molecular-beam-epitaxy grown Ge1-xSnxfilms treated by post-growth nanosecond-range pulsed laser melting (PLM). Doppler broadening - variable energy positron annihilation spectroscopy and variable energy positron annihilation lifetime spectroscopy are used to investigate the defect nanostructure in the Ge1-xSnxfilms exposed to increasing laser energy density. The experimental results, supported with ATomic SUPerposition calculations, evidence that after PLM, the average size of the open volume defects increases, which represents a raise in concentration of vacancy agglomerations, but the overall defect density is reduced as a function of the PLM fluence. At the same time, the positron annihilation spectroscopy analysis provides information about dislocations and Ge vacancies decorated by Sn atoms. Moreover, it is shown that the PLM reduces the strain in the layer, while dislocations are responsible for trapping of Sn and formation of small Sn-rich-clusters.
Collapse
Affiliation(s)
- O Steuer
- Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstrasse 400, 01328 Dresden, Germany
- Institute of Materials Science, Technische Universität Dresden, Budapester Str. 27, 01069 Dresden, Germany
| | - M O Liedke
- Institute of Radiation Physics, Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstrasse 400, 01328 Dresden, Germany
| | - M Butterling
- Institute of Radiation Physics, Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstrasse 400, 01328 Dresden, Germany
| | - D Schwarz
- University of Stuttgart, Institute of Semiconductor Engineering, 70569 Stuttgart, Germany
| | - J Schulze
- Fraunhofer Institute for Integrated Systems and Device Technology IISB, 91058 Erlangen, Germany
| | - Z Li
- Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstrasse 400, 01328 Dresden, Germany
| | - A Wagner
- Institute of Radiation Physics, Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstrasse 400, 01328 Dresden, Germany
| | - I A Fischer
- Experimental Physics and Functional Materials, Brandenburgische Technische Universität Cottbus-Senftenberg, 03046 Cottbus, Germany
| | - R Hübner
- Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstrasse 400, 01328 Dresden, Germany
| | - S Zhou
- Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstrasse 400, 01328 Dresden, Germany
| | - M Helm
- Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstrasse 400, 01328 Dresden, Germany
- Center for Advancing Electronics Dresden, Technische Universität Dresden, Helmholtzstraße 18, 01062 Dresden, Germany
| | - G Cuniberti
- Institute of Materials Science, Technische Universität Dresden, Budapester Str. 27, 01069 Dresden, Germany
| | - Y M Georgiev
- Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstrasse 400, 01328 Dresden, Germany
- Institute of Electronics, Bulgarian Academy of Sciences, 72, Tsarigradsko Chausse Blvd., 1784 Sofia, Bulgaria
| | - S Prucnal
- Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstrasse 400, 01328 Dresden, Germany
| |
Collapse
|
3
|
Zhang T, Qi N, Su X, Tang X, Chen Z. Vacancy Suppression Induced Synergetic Optimization of Thermoelectric Performance in Sb-Doped GeTe Evidenced by Positron Annihilation Spectroscopy. ACS Appl Mater Interfaces 2023; 15:40665-40675. [PMID: 37585556 DOI: 10.1021/acsami.3c08779] [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] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/18/2023]
Abstract
Synergetic optimization of the electrical and thermal transport performance of GeTe has been achieved through Sb doping in this work, resulting in a high thermoelectric figure of merit ZT of 2.2 at 723 K. Positron annihilation measurements provided clear evidence that Sb doping in GeTe can effectively suppress the Ge vacancies, and the decrease of vacancy concentration coincides well with the change of hole carrier concentration after Sb doping. The decreased scattering by hole carriers and vacancies causes notable increase in carrier mobility. Despite this, the density of states effective mass is not enhanced by Sb doping, a maximum power factor of 4562 μW m-1 K-2 at 723 K is obtained for Ge0.94Sb0.06Te with an optimized carrier concentration of ∼3.65 × 1020 cm-3. Meanwhile, the electronic thermal conductivity κe is reduced because of the decreased electrical conductivity σ with the increase of the Sb doping amount. In addition, the lattice thermal conductivity κL is also suppressed due to multiple phonon scattering mechanism, such as the large mass and strain fluctuations by the substitution of Sb for Ge atoms, and also the unique microstructure including grain boundary, nano-pore, and dislocation in the samples. In conclusion, a maximum ZT of 2.2 is gained at 723 K, which contributes to preferable TE property for GeTe-based materials.
Collapse
Affiliation(s)
- Tingdong Zhang
- Hubei Nuclear Solid Physics Key Laboratory, Department of Physics, Wuhan University, Wuhan 430072, China
| | - Ning Qi
- Hubei Nuclear Solid Physics Key Laboratory, Department of Physics, Wuhan University, Wuhan 430072, China
| | - Xianli Su
- State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070, China
| | - Xinfeng Tang
- State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070, China
| | - Zhiquan Chen
- Hubei Nuclear Solid Physics Key Laboratory, Department of Physics, Wuhan University, Wuhan 430072, China
| |
Collapse
|
4
|
Chen Z, Yang Y, Yao F, Yang Y, Li Y, Jia X, Dong J, Qian L, Chen W, Zou W, Zhao J, Pang J, Xu W, Wang Z, He G, Lin Q. Neutron Irradiation Effects on Boron Nitride-Based Ceramics for Use in X-ray Detection. ACS Appl Mater Interfaces 2023. [PMID: 37431755 DOI: 10.1021/acsami.3c05953] [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] [Subscribe] [Scholar Register] [Indexed: 07/12/2023]
Abstract
X-ray detectors based on conventional semiconductors with large atomic numbers are suffering from the poor stability under a high dose rate of ionizing irradiation. In this work, we demonstrate that a wide band gap ceramic-boron nitride with small atomic numbers could be used for sensitive X-ray detection. Boron nitride samples showed excellent resistance to ionizing radiation, which have been systematically studied with the neutron- and electron-aging experiments. Then, we fully analyzed the influence of these aging effects on the fundamental properties of boron nitride. Interestingly, we found that the boron nitride samples could maintain relatively good charge transport properties even after large dose of neutron irradiation. The fabricated X-ray detectors showed decent performance metrics, and the neutron-aged boron nitride even showed improved operational stability under continuous X-ray irradiation, suggesting the great potential for real applications.
Collapse
Affiliation(s)
- Zhiyuan Chen
- Hubei Key Laboratory of Radiation Chemistry and Functional Materials, School of Nuclear Technology and Chemistry & Biology, Hubei University of Science and Technology, Xianning, Hubei 437100, China
| | - Yujie Yang
- Key Lab of Artificial Micro- and Nano-Structures of Ministry of Education of China, School of Physics and Technology, Hubei Luojia Laboratory, Wuhan University, Wuhan, Hubei 430072, China
| | - Fang Yao
- Key Lab of Artificial Micro- and Nano-Structures of Ministry of Education of China, School of Physics and Technology, Hubei Luojia Laboratory, Wuhan University, Wuhan, Hubei 430072, China
| | - Yongfu Yang
- Key Lab of Artificial Micro- and Nano-Structures of Ministry of Education of China, School of Physics and Technology, Hubei Luojia Laboratory, Wuhan University, Wuhan, Hubei 430072, China
| | - Yuwei Li
- Key Lab of Artificial Micro- and Nano-Structures of Ministry of Education of China, School of Physics and Technology, Hubei Luojia Laboratory, Wuhan University, Wuhan, Hubei 430072, China
| | - Xuchao Jia
- Key Lab of Artificial Micro- and Nano-Structures of Ministry of Education of China, School of Physics and Technology, Hubei Luojia Laboratory, Wuhan University, Wuhan, Hubei 430072, China
| | - Junqi Dong
- Key Lab of Artificial Micro- and Nano-Structures of Ministry of Education of China, School of Physics and Technology, Hubei Luojia Laboratory, Wuhan University, Wuhan, Hubei 430072, China
| | - Libing Qian
- Hubei Key Laboratory of Radiation Chemistry and Functional Materials, School of Nuclear Technology and Chemistry & Biology, Hubei University of Science and Technology, Xianning, Hubei 437100, China
| | - Wanping Chen
- Key Lab of Artificial Micro- and Nano-Structures of Ministry of Education of China, School of Physics and Technology, Hubei Luojia Laboratory, Wuhan University, Wuhan, Hubei 430072, China
| | - Wusheng Zou
- Hubei Key Laboratory of Radiation Chemistry and Functional Materials, School of Nuclear Technology and Chemistry & Biology, Hubei University of Science and Technology, Xianning, Hubei 437100, China
| | - Jiangbin Zhao
- Department of Nuclear Technology and Application, China Institute of Atomic Energy, Beijing 102413, China
| | - Jinbiao Pang
- Yunke Electronics Co., Ltd, Zhenhua Group, Guiyang 550018, China
| | - Wen Xu
- Key Laboratory of Materials Physics, Institute of Solid State Physics, HFIPS, Chinese Academy of Sciences, Hefei 230031, China
| | - Zhu Wang
- Hubei Key Laboratory of Radiation Chemistry and Functional Materials, School of Nuclear Technology and Chemistry & Biology, Hubei University of Science and Technology, Xianning, Hubei 437100, China
| | - Gaokui He
- Department of Nuclear Technology and Application, China Institute of Atomic Energy, Beijing 102413, China
| | - Qianqian Lin
- Key Lab of Artificial Micro- and Nano-Structures of Ministry of Education of China, School of Physics and Technology, Hubei Luojia Laboratory, Wuhan University, Wuhan, Hubei 430072, China
| |
Collapse
|
5
|
Chen Y, Sun K, Zhang T, Zhou J, Liu Y, Zeng M, Ren X, Feng R, Yang Z, Zhang P, Wang B, Cao X. TiO(2)-Modified Montmorillonite-Supported Porous Carbon-Immobilized Pd Species Nanocomposite as an Efficient Catalyst for Sonogashira Reactions. Molecules 2023; 28. [PMID: 36903644 DOI: 10.3390/molecules28052399] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2023] [Revised: 02/26/2023] [Accepted: 03/02/2023] [Indexed: 03/08/2023] Open
Abstract
In this study, a combination of the porous carbon (PCN), montmorillonite (MMT), and TiO2 was synthesized into a composite immobilized Pd metal catalyst (TiO2-MMT/PCN@Pd) with effective synergism improvements in catalytic performance. The successful TiO2-pillaring modification for MMT, derivation of carbon from the biopolymer of chitosan, and immobilization of Pd species for the prepared TiO2-MMT/PCN@Pd0 nanocomposites were confirmed using a combined characterization with X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), N2 adsorption-desorption isotherms, high-resolution transition electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy. It was shown that the combination of PCN, MMT, and TiO2 as a composite support for the stabilization of the Pd catalysts could synergistically improve the adsorption and catalytic properties. The resultant TiO2-MMT80/PCN20@Pd0 showed a high surface area of 108.9 m2/g. Furthermore, it exhibited moderate to excellent activity (59-99% yield) and high stability (recyclable 19 times) in the liquid-solid catalytic reactions, such as the Sonogashira reactions of aryl halides (I, Br) with terminal alkynes in organic solutions. The positron annihilation lifetime spectroscopy (PALS) characterization sensitively detected the development of sub-nanoscale microdefects in the catalyst after long-term recycling service. This study provided direct evidence for the formation of some larger-sized microdefects during sequential recycling, which would act as leaching channels for loaded molecules, including active Pd species.
Collapse
|
6
|
Mohamed HFM, Abdel-Hady EE, Mohammed WM. Investigation of Transport Mechanism and Nanostructure of Nylon-6,6/PVA Blend Polymers. Polymers (Basel) 2022; 15:polym15010107. [PMID: 36616457 PMCID: PMC9823691 DOI: 10.3390/polym15010107] [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] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2022] [Revised: 11/23/2022] [Accepted: 12/23/2022] [Indexed: 12/29/2022] Open
Abstract
A casting technique was used to prepare poly(vinyl alcohol) (PVA) blend polymers with different concentrations of Nylon-6,6 to increase the free-volume size and control the ionic conductivity of the blended polymers. The thermal activation energy for some blends is lower than that of pure polymers, indicating that their thermal stability is somewhere in between that of pure Nylon-6,6 and pure PVA. The degree of crystallinity of the blend sample (25.7%) was lower than that of the pure components (41.0 and 31.6% for pure Nylon-6,6 and PVA, respectively). The dielectric properties of the blended samples were investigated for different frequencies (50 Hz-5 MHz). The σac versus frequency was found to obey Jonscher's universal power law. The calculated values of the s parameter were increased from 0.53 to 0.783 for 0 and 100 wt.% Nylon-6,6, respectively, and values less than 1 indicate the hopping conduction mechanism. The barrier height (Wm) was found to increase from 0.33 to 0.72 for 0 and 100 wt.% Nylon-6,6, respectively. The ionic conductivity decreases as the concentration of Nylon-6,6 is blended into PVA because increasing the Nylon-6,6 concentration reduces the number of mobile charge carriers. Positron annihilation lifetime (PAL) spectroscopy was used to investigate the free volume's nanostructure. The hole volume size grows exponentially with the concentration of Nylon-6,6 mixed with PVA. The Nylon-6,6/PVA blends' free-volume distribution indicates that there is no phase separation in the blended samples. Mixing PVA and Nylon-6,6 resulted in a negative deviation (miscible blends), as evidenced by the interaction parameter's negative value. The strong correlation between the free-volume size and other macroscopic properties like ionic conductivity suggests that the free-volume size influences these macroscopic properties.
Collapse
|
7
|
Goździuk M, Kavetskyy T, Roquero DM, Smutok O, Gonchar M, Královič DP, Švajdlenková H, Šauša O, Kalinay P, Nosrati H, Lebedevaite M, Grauzeliene S, Ostrauskaite J, Kiv A, Zgardzińska B. UV-Cured Green Polymers for Biosensorics: Correlation of Operational Parameters of Highly Sensitive Biosensors with Nano-Volumes and Adsorption Properties. Materials (Basel) 2022; 15:6607. [PMID: 36233949 PMCID: PMC9572821 DOI: 10.3390/ma15196607] [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] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/30/2022] [Revised: 09/13/2022] [Accepted: 09/16/2022] [Indexed: 06/16/2023]
Abstract
The investigated polymeric matrixes consisted of epoxidized linseed oil (ELO), acrylated epoxidized soybean oil (AESO), trimethylolpropane triglycidyl ether (RD1), vanillin dimethacrylate (VDM), triarylsulfonium hexafluorophosphate salts (PI), and 2,2-dimethoxy-2-phenylacetophenone (DMPA). Linseed oil-based (ELO/PI, ELO/10RD1/PI) and soybean oil-based (AESO/VDM, AESO/VDM/DMPA) polymers were obtained by cationic and radical photopolymerization reactions, respectively. In order to improve the cross-linking density of the resulting polymers, 10 mol.% of RD1 was used as a reactive diluent in the cationic photopolymerization of ELO. In parallel, VDM was used as a plasticizer in AESO radical photopolymerization reactions. Positron annihilation lifetime spectroscopy (PALS) was used to characterize vegetable oil-based UV-cured polymers regarding their structural stability in a wide range of temperatures (120-320 K) and humidity. The polymers were used as laccase immobilization matrixes for the construction of amperometric biosensors. A direct dependence of the main operational parameters of the biosensors and microscopical characteristics of polymer matrixes (mostly on the size of free volumes and water content) was established. The biosensors are intended for the detection of trace water pollution with xenobiotics, carcinogenic substances with a very negative impact on human health. These findings will allow better predictions for novel polymers as immobilization matrixes for biosensing or biotechnology applications.
Collapse
Affiliation(s)
- Magdalena Goździuk
- Institute of Physics, Maria Curie-Sklodowska University, 20-031 Lublin, Poland
| | - Taras Kavetskyy
- Department of Biology and Chemistry, Drohobych Ivan Franko State Pedagogical University, 82100 Drohobych, Ukraine
- Department of Materials Engineering, The John Paul II Catholic University of Lublin, 20-950 Lublin, Poland
| | - Daniel Massana Roquero
- Department of Chemistry and Biomolecular Science, Clarkson University, Potsdam, NY 13699-5810, USA
| | - Oleh Smutok
- Department of Chemistry and Biomolecular Science, Clarkson University, Potsdam, NY 13699-5810, USA
- Department of Analytical Biotechnology, Institute of Cell Biology, National Academy of Sciences of Ukraine, 79005 Lviv, Ukraine
| | - Mykhailo Gonchar
- Department of Biology and Chemistry, Drohobych Ivan Franko State Pedagogical University, 82100 Drohobych, Ukraine
- Department of Analytical Biotechnology, Institute of Cell Biology, National Academy of Sciences of Ukraine, 79005 Lviv, Ukraine
| | - David P. Královič
- Department of Nuclear Chemistry, Comenius University in Bratislava, 84215 Bratislava, Slovakia
| | | | - Ondrej Šauša
- Department of Nuclear Chemistry, Comenius University in Bratislava, 84215 Bratislava, Slovakia
- Institute of Physics, Slovak Academy of Sciences, 84511 Bratislava, Slovakia
| | - Pavol Kalinay
- Institute of Physics, Slovak Academy of Sciences, 84511 Bratislava, Slovakia
| | - Hamed Nosrati
- Department of Pharmaceutical Biomaterials, School of Pharmacy, Zanjan University of Medical Sciences, Zanjan 45139-56111, Iran
| | - Migle Lebedevaite
- Department of Polymer Chemistry and Technology, Kaunas University of Technology, 50254 Kaunas, Lithuania
| | - Sigita Grauzeliene
- Department of Polymer Chemistry and Technology, Kaunas University of Technology, 50254 Kaunas, Lithuania
| | - Jolita Ostrauskaite
- Department of Polymer Chemistry and Technology, Kaunas University of Technology, 50254 Kaunas, Lithuania
| | - Arnold Kiv
- Department of Innovation Technologies, South-Ukrainian K.D. Ushynsky National Pedagogical University, 65020 Odesa, Ukraine
| | - Bożena Zgardzińska
- Institute of Physics, Maria Curie-Sklodowska University, 20-031 Lublin, Poland
| |
Collapse
|
8
|
Bordulev I, Laptev R, Kudiiarov V, Elman R, Popov A, Kabanov D, Ushakov I, Lider A. Positron Annihilation Spectroscopy Complex for Structural Defect Analysis in Metal-Hydrogen Systems. Materials (Basel) 2022; 15:1823. [PMID: 35269054 DOI: 10.3390/ma15051823] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/16/2022] [Revised: 02/15/2022] [Accepted: 02/26/2022] [Indexed: 11/17/2022]
Abstract
The current work is devoted to developing a system for the complex research of metal-hydrogen systems, including in an in situ mode. The system consists of a controlled gas reactor with a unique reaction chamber, a radioisotope positron source, and a positron annihilation spectroscopy complex. The use of the system enables in situ investigation of the defect structure of solids in hydrogen sorption-desorption processes at temperatures up to 900 °C and pressures up to 50 bar. Experimental investigations of magnesium and magnesium hydride during thermal annealing were carried out to approve the possibilities of the developed complex. It was shown that one cycle of magnesium hydrogenation-dehydrogenation resulted in the accumulation of irreversible hydrogen-induced defects. The defect structure investigation of the magnesium-hydrogen system by positron annihilation techniques was supplemented with a comprehensive study by scanning electron microscopy, X-ray diffraction analysis, and hydrogen sorption-desorption studies.
Collapse
|
9
|
Li J, Laptev R, Bordulev I, Siemek K, Horodek P, Shen H, Lomygin A, Cui J. Positron Annihilation Spectroscopy Study of Metallic Materials after High-Speed Cutting. Materials (Basel) 2022; 15:ma15031017. [PMID: 35160960 PMCID: PMC8838609 DOI: 10.3390/ma15031017] [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] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/15/2021] [Revised: 01/22/2022] [Accepted: 01/27/2022] [Indexed: 11/16/2022]
Abstract
During high-speed cutting, a white layer is often produced on the machined surfaces after mechanical machining, seriously affecting the mechanical properties. These properties are related to the material structure and the defects induced by cutting. However, there is a lack of research on the atomic-scale defects of the white layer. This paper studied the influence of cutting parameters, namely the feed rate, cutting speed and cutting depth, on atomic-scale defects induced by high-speed cutting in GCr15 steel. Positron annihilation studies showed typical plastically deformed or tempered carbon steel defects with additional vacancy cluster components. The quantity of these clusters changed with cutting parameters. Furthermore, significant changes were observed in the subsurface region up to 1 µm, occurring as a result of simultaneous phase transformations, deformation and thermal impacts. The predominant accumulation of only one type of atomic-scale defect was not observed.
Collapse
Affiliation(s)
- Jinquan Li
- School of Mechanical Engineering, Shenyang Ligong University, No.6 Nanping Center Road, Hunnan New District, Shenyang 110159, China;
- Correspondence: (J.L.); (R.L.); Tel.: +7-913-852-3733 (R.L.)
| | - Roman Laptev
- Division for Experimental Physics, National Research Tomsk Polytechnic University, 634050 Tomsk, Russia; (I.B.); (A.L.); (J.C.)
- Correspondence: (J.L.); (R.L.); Tel.: +7-913-852-3733 (R.L.)
| | - Iurii Bordulev
- Division for Experimental Physics, National Research Tomsk Polytechnic University, 634050 Tomsk, Russia; (I.B.); (A.L.); (J.C.)
| | - Krzysztof Siemek
- Institute of Nuclear Physics Polish Academy of Sciences, PL-31342 Krakow, Poland; (K.S.); (P.H.)
- Joint Institute for Nuclear Research, Joliot-Curie 6, 141980 Dubna, Russia
| | - Pawel Horodek
- Institute of Nuclear Physics Polish Academy of Sciences, PL-31342 Krakow, Poland; (K.S.); (P.H.)
- Joint Institute for Nuclear Research, Joliot-Curie 6, 141980 Dubna, Russia
| | - Haolun Shen
- School of Mechanical Engineering, Shenyang Ligong University, No.6 Nanping Center Road, Hunnan New District, Shenyang 110159, China;
| | - Anton Lomygin
- Division for Experimental Physics, National Research Tomsk Polytechnic University, 634050 Tomsk, Russia; (I.B.); (A.L.); (J.C.)
| | - Jian Cui
- Division for Experimental Physics, National Research Tomsk Polytechnic University, 634050 Tomsk, Russia; (I.B.); (A.L.); (J.C.)
| |
Collapse
|
10
|
Tao Q, Wu H, Pan W, Zhang Z, Tang Y, Wu Y, Fan R, Chen Z, Wu J, Su X, Tang X. Removing the Oxygen-Induced Donor-like Effect for High Thermoelectric Performance in n-Type Bi 2Te 3-Based Compounds. ACS Appl Mater Interfaces 2021; 13:60216-60226. [PMID: 34874703 DOI: 10.1021/acsami.1c19357] [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
Bismuth telluride-based alloys are the best performing thermoelectric materials near room temperature. Grain size refinement and nanostructuring are the core stratagems for improving thermoelectric and mechanical properties. However, the donor-like effect induced by grain size refinement strongly restricts the thermoelectric properties especially in the vicinity of room temperature. In this study, the formation mechanism for the donor-like effect in Bi2Te3-based compounds was revealed by synthesizing five batches of polycrystalline samples. We demonstrate that the donor-like effect in Bi2Te3-based compounds is strongly related to the vacancy defects (VBi‴ and VTe···) induced by the fracturing process and oxygen in air for the first time. The oxygen-induced donor-like effect dramatically increases the carrier concentration from 2.5 × 1019 cm-3 for the zone melting ingot and bulks sintered with powders ground under an inert atmosphere to 7.5 × 1019 cm-3, which is largely beyond the optimum carrier concentration and seriously deteriorates the thermoelectric performance. Moreover, it is found that both avoiding exposure to air and eliminating the thermal vacancy defects (VBi‴ and VTe···) via heat treatment before exposure to air can effectively remove the donor-like effect, producing almost the same carrier concentration and Seebeck coefficient as those of the zone melting ingot for these samples. Therefore, a defect equation of oxygen-induced donor-like effect was proposed and was further explicitly corroborated by positron annihilation measurement. With the removal of donor-like effect and improved texturing via multiple hot deformation (HD) processes, a maximum power factor of 3.5 mW m-1 K-2 and a reproducible maximum ZT value of 1.01 near room temperature are achieved. This newly proposed defect equation of the oxygen-induced donor-like effect will provide a guideline for developing higher-performance V2VI3 polycrystalline materials for near-room-temperature applications.
Collapse
Affiliation(s)
- Qirui Tao
- State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070, China
| | - Huijuan Wu
- Hubei Nuclear Solid Physics Key Laboratory, Department of Physics, Wuhan University, Wuhan 430072, China
| | - Wenfeng Pan
- Hubei Nuclear Solid Physics Key Laboratory, Department of Physics, Wuhan University, Wuhan 430072, China
- College of Basic Sciences, Zhengzhou University of Technology, Zhengzhou 450044, China
| | - Zhengkai Zhang
- State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070, China
| | - Yinfei Tang
- State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070, China
- International School of Materials Science and Engineering, Wuhan University of Technology, Wuhan 430070, China
| | - Yutian Wu
- State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070, China
| | - Renjie Fan
- State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070, China
| | - Zhiquan Chen
- Hubei Nuclear Solid Physics Key Laboratory, Department of Physics, Wuhan University, Wuhan 430072, China
| | - Jinsong Wu
- State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070, China
- Nanostructure Research Center, Wuhan University of Technology, Wuhan 430070, China
| | - Xianli Su
- State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070, China
| | - Xinfeng Tang
- State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070, China
| |
Collapse
|
11
|
Klym H, Karbovnyk I, Piskunov S, Popov AI. Positron Annihilation Lifetime Spectroscopy Insight on Free Volume Conversion of Nanostructured MgAl 2O 4 Ceramics. Nanomaterials (Basel) 2021; 11:3373. [PMID: 34947722 DOI: 10.3390/nano11123373] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/18/2021] [Revised: 12/09/2021] [Accepted: 12/10/2021] [Indexed: 11/17/2022]
Abstract
Herein we demonstrate the specifics of using the positron annihilation lifetime spectroscopy (PALS) method for the study of free volume changes in functional ceramic materials. Choosing technological modification of nanostructured MgAl2O4 spinel as an example, we show that for ceramics with well-developed porosity positron annihilation is revealed through two channels: positron trapping channel and ortho-positronium decay. Positron trapping in free-volume defects is described by the second component of spectra and ortho-positronium decay process by single or multiple components, depending on how well porosity is developed and on the experimental configuration. When using proposed positron annihilation lifetime spectroscopy approaches, three components are the most suitable fit in the case of MgAl2O4 ceramics. In the analysis of the second component, it is shown that technological modification (increasing sintering temperature) leads to volume shrinking and decreases the number of defect-related voids. This process is also accompanied by the decrease of the size of nanopores (described by the third component), while the overall number of nanopores is not affected. The approach to the analysis of positron annihilation lifetime spectra presented here can be applied to a wide range of functional nanomaterials with pronounced porosity.
Collapse
|
12
|
Sun Y, Li T, Dai H, Wang M, Xue R, Chen J, Liu D. Preparation and Characterization of Intrinsic Low-κ Polyimide Films. Polymers (Basel) 2021; 13:polym13234174. [PMID: 34883677 PMCID: PMC8659940 DOI: 10.3390/polym13234174] [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] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2021] [Revised: 11/19/2021] [Accepted: 11/26/2021] [Indexed: 11/16/2022] Open
Abstract
Three fluorinated polyimide (PI-FP, PI-FO and PI-FH) films with low dielectric constants and excellent comprehensive properties were successfully prepared using a polycondensation reaction method by incorporating p-phenylenediamine (PDA), 4-4′-diaminodiphenyl ether (ODA) and 4,4′-(Hexafluoroisopropylidene) bis (p-phenyleneoxy) dianiline (HFPBDA) into 4,4′-(Hexafluoroisopropylidene) diphthalic anhydride (6FDA), respectively. The effects of the diamine monomer structure on optical, dielectric and mechanical properties were investigated. Compared with PDA and ODA, HFPBDA can effectively improve the optical and dielectric properties of PI due to due to its special chain structure. Among the three PI films, PI-FH film presents the best optic transmission (highest transmittance = 90.2%) and highest energy gap (2.69 eV). The dielectric properties of PI-FH film improve the most. The dielectric constant and loss at 104 Hz are reduced to 2.05 and 0.0034 at 104 Hz, respectively, and remain stable up to 250 °C. The mechanical properties decrease in turn for PI-FP, PI-FO and PI-FH films due to the increase in free volume fraction. Nevertheless, PI-FH film still exhibits good mechanical properties with a tensile strength of 88.4 Mpa, a tensile modulus of 2.11 GPa and an elongation at break of 4.1%. The correlation between the dielectric and mechanical properties of PI films and their free volume characteristics is well explained with the help of positron annihilation spectroscopy.
Collapse
|
13
|
Li K, Kashkarov E, Ma H, Fan P, Zhang Q, Zhang P, Zhang J, Wu Z, Wahl L, Laptev R, Lider A, Travitzky N, Yuan D. Microstructural Analysis of Novel Preceramic Paper-Derived SiC f/SiC Composites. Materials (Basel) 2021; 14:6737. [PMID: 34832140 DOI: 10.3390/ma14226737] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/07/2021] [Revised: 10/27/2021] [Accepted: 11/02/2021] [Indexed: 11/17/2022]
Abstract
This paper presents the results of microstructural analysis of novel preceramic paper-derived SiCf/SiC composites fabricated by spark plasma sintering. The sintering temperature and pressure were 2100/2200 °C and 60/100 MPa, respectively. The content of fibers in the composites was approx. 10 wt %. The SiCf/SiC composites were analyzed by positron annihilation methods, X-ray diffraction technology, scanning electron microscopy, and Raman spectroscopy. Longer sintering time causes the proportion of the 6H-SiC composition to increase to ~80%. The increase in sintering temperature from 2100 °C to 2200 °C leads to partial transition of 4H-SiC to 6H-SiC during the sintering process, and the long-life component of positrons indicates the formation of Si vacancies. The Raman characteristic peaks of turbostratic graphite appear in the Raman spectrum of SiC fibers, this is caused by the diffusion of carbon from the surface of the SiC fiber and the preceramic paper during the high-temperature sintering process.
Collapse
|
14
|
Han X, Chen T, Zhao Y, Gao J, Sang Y, Xiong H, Chen Z. Relationship between the Microstructure and Performance of Graphene/Polyethylene Composites Investigated by Positron Annihilation Lifetime Spectroscopy. Nanomaterials (Basel) 2021; 11:2990. [PMID: 34835754 PMCID: PMC8619168 DOI: 10.3390/nano11112990] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/20/2021] [Revised: 10/22/2021] [Accepted: 11/03/2021] [Indexed: 11/29/2022]
Abstract
The quantitative characterization of microstructure is most desirable for the establishment of structure-property relationships in polymer nanocomposites. In this work, the effects of graphene on the microstructure, mechanical, electrical, and thermal properties of the obtained graphene/polyethylene (PE) composites were investigated. In order to reveal the structure-performance relationship of graphene/PE composites, especially for the effects of the relative free volume fraction (fr) and interfacial interaction intensity (β), positron annihilation lifetime spectroscopy (PALS) was employed for its quantitative description. The relative free volume fraction fr gives a good explanation of the variation for surface resistivity, melting temperature, and thermal stability, and the variation of tensile strength and thermal conductivity agree well with the results of interfacial interaction intensity β. The results showed that fr and β have a significant effect on the properties of the obtained graphene/PE composites, and the effect on the properties was revealed.
Collapse
Affiliation(s)
| | | | | | - Jie Gao
- Hubei Key Laboratory of Radiation Chemistry and Functional Materials, School of Nuclear Technology and Chemistry & Biology, Hubei University of Science and Technology, Xianning 437100, China; (X.H.); (T.C.); (Y.Z.); (Y.S.); (H.X.)
| | | | | | - Zhiyuan Chen
- Hubei Key Laboratory of Radiation Chemistry and Functional Materials, School of Nuclear Technology and Chemistry & Biology, Hubei University of Science and Technology, Xianning 437100, China; (X.H.); (T.C.); (Y.Z.); (Y.S.); (H.X.)
| |
Collapse
|
15
|
Bordulev I, Laptev R, Kabanov D, Ushakov I, Kudiiarov V, Lider A. Source for In Situ Positron Annihilation Spectroscopy of Thermal-And Hydrogen-Induced Defects Based on the Cu-64 Isotope. Materials (Basel) 2021; 14:6693. [PMID: 34772219 DOI: 10.3390/ma14216693] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/19/2021] [Revised: 10/21/2021] [Accepted: 11/02/2021] [Indexed: 11/20/2022]
Abstract
This work aims to investigate the 64Cu isotope applicability for positron annihilation experiments in in situ mode. We determined appropriate characteristics of this isotope for defect studies and implemented them under aggressive conditions (i.e., elevated temperature, hydrogen environment) in situ to determine the sensitivity of this approach to thermal vacancies and hydrogen-induced defects investigation. Titanium samples were used as test materials. The source was obtained by the activation of copper foil in the thermal neutron flux of a research nuclear reactor. Main spectrometric characteristics (e.g., the total number of counts, fraction of good signals, peak-to-noise ratio) of this source, as well as line-shaped parameters of the Doppler broadening spectrum (DBS), were studied experimentally. These characteristics for 64Cu (in contrast to positron sources with longer half-life) were shown to vary strongly with time, owing to the rapidly changing activity. These changes are predictable and should be considered in the analysis of experimental data to reveal information about the defect structure. The investigation of samples with a controlled density of defects revealed the suitability of 64Cu positron source with an activity of 2–40 MBq for defects studies by DBS. However, greater isotope activity could also be applied. The results of testing this source at high temperatures and in hydrogen atmosphere showed its suitability to thermal vacancies and hydrogen-induced defects studies in situ. The greatest changes in the defect structure of titanium alloy during high-temperature hydrogen saturation occurred at the cooling stage, when the formation of hydrides began, and were associated with an increase in the dislocation density.
Collapse
|
16
|
Gorelov BM, Mischanchuk OV, Sigareva NV, Shulga SV, Gorb AM, Polovina OI, Yukhymchuk VO. Structural and Dipole-Relaxation Processes in Epoxy-Multilayer Graphene Composites with Low Filler Content. Polymers (Basel) 2021; 13:3360. [PMID: 34641174 PMCID: PMC8512419 DOI: 10.3390/polym13193360] [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] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2021] [Revised: 08/26/2021] [Accepted: 08/29/2021] [Indexed: 11/16/2022] Open
Abstract
Multilayered graphene nanoplatelets (MLGs) were prepared from thermally expanded graphite flakes using an electrochemical technique. Morphological characterization of MLGs was performed using scanning electron microscopy (SEM), X-ray diffraction analysis (XRD), Raman spectroscopy (RS), and the Brunauer-Emmett-Teller (BET) method. DGEBA-epoxy-based nanocomposites filled with synthesized MLGs were studied using Static Mechanical Loading (SML), Thermal Desorption Mass Spectroscopy (TDMS), Broad-Band Dielectric Spectroscopy (BDS), and Positron Annihilation Lifetime Spectroscopy (PALS). The mass loading of the MLGs in the nanocomposites was varied between 0.0, 0.1, 0.2, 0.5, and 1% in the case of the SML study and 0.0, 1.0, 2, and 5% for the other measurements. Enhancements in the compression strength and the Young's modulus were obtained at extremely low loadings (C≤ 0.01%). An essential increase in thermal stability and a decrease in destruction activation energy were observed at C≤ 5%. Both the dielectric permittivity (ε1) and the dielectric loss factor (ε2) increased with increasing C over the entire frequency region tested (4 Hz-8 MHz). Increased ε2 is correlated with decreased free volume when increasing C. Physical mechanisms of MLG-epoxy interactions underlying the effects observed are discussed.
Collapse
Affiliation(s)
- Borys M. Gorelov
- Department of Composite Materials, Chuiko Institute of Surface Chemistry of the National Academy of Sciences of Ukraine, 03164 Kyiv, Ukraine; (B.M.G.); (O.V.M.); (N.V.S.); (S.V.S.)
| | - Oleksandr V. Mischanchuk
- Department of Composite Materials, Chuiko Institute of Surface Chemistry of the National Academy of Sciences of Ukraine, 03164 Kyiv, Ukraine; (B.M.G.); (O.V.M.); (N.V.S.); (S.V.S.)
| | - Nadia V. Sigareva
- Department of Composite Materials, Chuiko Institute of Surface Chemistry of the National Academy of Sciences of Ukraine, 03164 Kyiv, Ukraine; (B.M.G.); (O.V.M.); (N.V.S.); (S.V.S.)
| | - Sergey V. Shulga
- Department of Composite Materials, Chuiko Institute of Surface Chemistry of the National Academy of Sciences of Ukraine, 03164 Kyiv, Ukraine; (B.M.G.); (O.V.M.); (N.V.S.); (S.V.S.)
| | - Alla M. Gorb
- Faculty of Physics, Taras Shevchenko National University of Kyiv, 01601 Kyiv, Ukraine;
| | - Oleksiy I. Polovina
- Faculty of Physics, Taras Shevchenko National University of Kyiv, 01601 Kyiv, Ukraine;
| | - Volodymyr O. Yukhymchuk
- Department of Optics and Spectroscopy of Semiconductor and Dielectric Materials, V. Lashkaryov Institute of Semiconductor Physics of the National Academy of Sciences of Ukraine, 03028 Kyiv, Ukraine;
| |
Collapse
|
17
|
Abstract
The results ofthe sorption properties of cellulose acetate (CA) with different degrees of substitution (SD) are summarised. It has been shown that the sorption capacity of CA in water vapour decreases naturally with increasing content of acetate groups in monomeric units of cellulose ethers. The experimental isotherms are analysed according to the double sorption model. Hydrate numbers of hydroxyl and acetate groups were determined. The paired parameters of the Flory–Huggins interaction were calculated. It is shown that the decrease of the Langmuir component is due to the replacement of hydroxyl groups by ester groups, whose local sorption capacity by water vapour is lower than the sorption capacity of OH groups. In the area of high humidity, there is an increase in vacancy sizes due to plasticisation of the sorbents.
Collapse
|
18
|
Beiranvand A, Liedke MO, Haalisto C, Lähteenlahti V, Schulman A, Granroth S, Palonen H, Butterling M, Wagner A, Huhtinen H, Paturi P. Tuned AFM-FM coupling by the formation of vacancy complex in Gd 0.6Ca 0.4MnO 3thin film lattice. J Phys Condens Matter 2021; 33:255803. [PMID: 33878744 DOI: 10.1088/1361-648x/abf9ba] [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] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/21/2021] [Accepted: 04/20/2021] [Indexed: 06/12/2023]
Abstract
The effect ofin situoxygen and vacuum annealings on the low bandwidth manganite Gd1-xCaxMnO3(GCMO) thin film withx= 0.4 was investigated. Based on the magnetic measurements, the AFM-FM coupling is suppressed by the vacuum annealing treatment via destroying the double exchange interaction and increasing the unit cell volume by converting the Mn4+to the Mn3+. Consequently, resistance increases significantly compared to pristine film. The results are explained by a model obtained from the positron annihilation studies, where the vacuum annealing increased the annihilation lifetime in A and B sites due to the formation of vacancy complexesVA,B-VO, which was not the case in the pristine sample. The positron annihilation analysis indicated that most of the open volume defects have been detected in the interface region rather than on the subsurface layer and this result is confirmed by detailed x-ray reflection analysis. On the other hand, the effect of oxygen annealing on the unit cell volume and magnetization was insignificant. This is in agreement with positron annihilation results which demonstrated that the introduction of oxygen does not change the number of cation vacancies significantly. This work demonstrates that the modification of oxygen vacancies and vacancy complexes can tune magnetic and electronic structure of the epitaxial thin films to provide new functionalities in future applications.
Collapse
Affiliation(s)
- A Beiranvand
- Wihuri Physical Laboratory, Department of Physics and Astronomy, University of Turku, FI-20014 Turku, Finland
| | - M O Liedke
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiation Physics, Bautzner Landstraße 400, 01328 Dresden, Germany
| | - C Haalisto
- Laboratory of Materials Science, Department of Physics and Astronomy, University of Turku, FI-20014 Turku, Finland
| | - V Lähteenlahti
- Wihuri Physical Laboratory, Department of Physics and Astronomy, University of Turku, FI-20014 Turku, Finland
| | - A Schulman
- Wihuri Physical Laboratory, Department of Physics and Astronomy, University of Turku, FI-20014 Turku, Finland
| | - S Granroth
- Laboratory of Materials Science, Department of Physics and Astronomy, University of Turku, FI-20014 Turku, Finland
| | - H Palonen
- Wihuri Physical Laboratory, Department of Physics and Astronomy, University of Turku, FI-20014 Turku, Finland
| | - M Butterling
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiation Physics, Bautzner Landstraße 400, 01328 Dresden, Germany
| | - A Wagner
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiation Physics, Bautzner Landstraße 400, 01328 Dresden, Germany
| | - H Huhtinen
- Wihuri Physical Laboratory, Department of Physics and Astronomy, University of Turku, FI-20014 Turku, Finland
| | - P Paturi
- Wihuri Physical Laboratory, Department of Physics and Astronomy, University of Turku, FI-20014 Turku, Finland
| |
Collapse
|
19
|
Arutyunov N, Krause-Rehberg R, Elsayed M, Emtsev V, Abrosimov N, Oganesyan G, Kozlovski V. Microstructure of bismuth centers in silicon before and after irradiation with 15 MeV protons. J Phys Condens Matter 2021; 33:245702. [PMID: 33626521 DOI: 10.1088/1361-648x/abe96f] [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] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/21/2020] [Accepted: 02/24/2021] [Indexed: 06/12/2023]
Abstract
A decrease of two-gamma annihilation rate of a positron in a strong spin-orbit field of the annihilation site of bismuth impurity center209Bi (J= 9/2) in silicon with natural isotope composition was revealed (Jis the nuclear spin). This decrease was observed along with increasing occupancy of Bi donor states (binding energyE{Bi} ≈ 69 meV). Atoms of29Si (J= 1/2) isotope are involved in spin interactions of positron with Bi impurity centers. The growth of occupancy of Bi donor states inhibits two-gamma annihilation rate. The estimated cross-section of positron trapping by the Bi impurity center isσ+≈ (1.23-1.5) × 10-13 cm2. Together with this surprisingly large value, the integral rate of two-gamma annihilation in a hypothetical polyelectron system of the Bi impurity center is by a factor of just Δ ∼ 2.18 higher compared to the magnitude ≈2.09 × 109 s-1known for elemental isolated polyelectron, (e-e+e-). Possible formation of the positron-containing exciton-like states, (e+)D0X(D= Bi, P) is also discussed. Irradiation of material with 15 MeV protons results in decreasing the factor Δ by ∼11% due to forming the radiation complex in which Bi atom is in an open volume ambient it. Such complex is suggested to haveD3dsymmetry and be the deep donor. Low-temperature measurements of both the positron annihilation rate and Hall effect have been applied for studying the isochronal annealing of these point radiation defects which were found to be thermally stable up to ∼370 °C; they can be annealed at ∼430 °C - 470 °C. According to available data ofab initiocluster calculations, the complex of Bi atom with a simulated vacancy hasD3dsymmetry with the energy gain ∼0.92 eV, thus indicating qualitative agreement between experimental and theoretical data.
Collapse
Affiliation(s)
- Nikolay Arutyunov
- Martin Luther University Halle, Department of Physics, 06120, Halle, Germany
- Ioffe Physico-Technical Institute, 194021, St. Petersburg, Russia
| | | | - Mohamed Elsayed
- Martin Luther University Halle, Department of Physics, 06120, Halle, Germany
- Minia University, Department of Physics, Faculty of Science, 61519, Minia, Egypt
| | - Vadim Emtsev
- Ioffe Physico-Technical Institute, 194021, St. Petersburg, Russia
| | - Nikolay Abrosimov
- Leibniz-lnstitut für Kristallzüchtung (IKZ), D-12489, Berlin, Germany
| | - Gagik Oganesyan
- Ioffe Physico-Technical Institute, 194021, St. Petersburg, Russia
| | - Vitalii Kozlovski
- St. Petersburg State Polytechnical University, 195251, St. Petersburg, Russia
| |
Collapse
|
20
|
Hoffmann RC, Sanctis S, Liedke MO, Butterling M, Wagner A, Njel C, Schneider JJ. Zinc Oxide Defect Microstructure and Surface Chemistry Derived from Oxidation of Metallic Zinc: Thin-Film Transistor and Sensor Behavior of ZnO Films and Rods. Chemistry 2021; 27:5422-5431. [PMID: 33241921 PMCID: PMC8048417 DOI: 10.1002/chem.202004270] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2020] [Indexed: 11/15/2022]
Abstract
Zinc oxide thin films are fabricated by controlled oxidation of sputtered zinc metal films on a hotplate in air at temperatures between 250 and 450 °C. The nanocrystalline films possess high relative densities and show preferential growth in (100) orientation. Integration in thin-film transistors reveals moderate charge carrier mobilities as high as 0.2 cm2 V-1 s-1 . The semiconducting properties depend on the calcination temperature, whereby the best performance is achieved at 450 °C. The defect structure of the thin ZnO film can be tracked by Doppler-broadening positron annihilation spectroscopy as well as positron lifetime studies. Comparably long positron lifetimes suggest interaction of zinc vacancies (VZn ) with one or more oxygen vacancies (VO ) in larger structural entities. Such VO -VZn defect clusters act as shallow acceptors, and thus, reduce the overall electron conductivity of the film. The concentration of these defect clusters decreases at higher calcination temperatures as indicated by changes in the S and W parameters. Such zinc oxide films obtained by conversion of metallic zinc can also be used as seed layers for solution deposition of zinc oxide nanowires employing a mild microwave-assisted process. The functionality of the obtained nanowire arrays is tested in a UV sensor device. The best results with respect to sensor sensitivity are achieved with thinner seed layers for device construction.
Collapse
Affiliation(s)
- Rudolf C. Hoffmann
- Eduard-Zintl-Institute for Inorganic and Physical ChemistryTechnical University DarmstadtAlarich-Weiss-Straße 1264287DarmstadtGermany
| | - Shawn Sanctis
- Eduard-Zintl-Institute for Inorganic and Physical ChemistryTechnical University DarmstadtAlarich-Weiss-Straße 1264287DarmstadtGermany
| | - Maciej O. Liedke
- Institute of Radiation PhysicsHelmholtz-Zentrum Dresden-RossendorfBautzner Landstraße 40001328DresdenGermany
| | - Maik Butterling
- Institute of Radiation PhysicsHelmholtz-Zentrum Dresden-RossendorfBautzner Landstraße 40001328DresdenGermany
| | - Andreas Wagner
- Institute of Radiation PhysicsHelmholtz-Zentrum Dresden-RossendorfBautzner Landstraße 40001328DresdenGermany
| | - Christian Njel
- Institute for Applied Materials—Energy StorageKarlsruhe Institute of Technology (KIT)Hermann-von-Helmholtz-Platz 176344Eggenstein- LeopoldshafenGermany
| | - Jörg J. Schneider
- Eduard-Zintl-Institute for Inorganic and Physical ChemistryTechnical University DarmstadtAlarich-Weiss-Straße 1264287DarmstadtGermany
| |
Collapse
|
21
|
Colombi G, De Krom T, Chaykina D, Cornelius S, Eijt SWH, Dam B. Influence of Cation (RE = Sc, Y, Gd) and O/H Anion Ratio on the Photochromic Properties of REO x H 3-2x Thin Films. ACS Photonics 2021; 8:709-715. [PMID: 33842670 PMCID: PMC8025701 DOI: 10.1021/acsphotonics.0c01877] [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] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/10/2020] [Indexed: 06/12/2023]
Abstract
Rare-earth oxyhydride REO x H3-2x thin films prepared by air-oxidation of reactively sputtered REH2 dihydrides show a color-neutral, reversible photochromic effect at ambient conditions. The present work shows that the O/H anion ratio, as well as the choice of the cation, allow to largely tune the extent of the optical change and its speed. The bleaching time, in particular, can be reduced by an order of magnitude by increasing the O/H ratio, indirectly defined by the deposition pressure of the parent REH2. The influence of the cation (RE = Sc, Y, Gd) under comparable deposition conditions is discussed. Our data suggest that REs of a larger ionic radius form oxyhydrides with a larger optical contrast and faster bleaching speed, hinting to a dependency of the photochromic mechanism on the anion site-hopping.
Collapse
Affiliation(s)
- Giorgio Colombi
- Materials
for Energy Conversion and Storage, Department of Chemical Engineering, Delft University of Technology, Van der Maasweg 9, NL-2629HZ Delft, The Netherlands
| | - Tom De Krom
- Fundamental
Aspects of Materials and Energy, Department of Radiation Science and
Technology, Faculty of Applied Sciences, Delft University of Technology, Mekelweg 15, NL-2629
JB Delft, The Netherlands
| | - Diana Chaykina
- Materials
for Energy Conversion and Storage, Department of Chemical Engineering, Delft University of Technology, Van der Maasweg 9, NL-2629HZ Delft, The Netherlands
- Fundamental
Aspects of Materials and Energy, Department of Radiation Science and
Technology, Faculty of Applied Sciences, Delft University of Technology, Mekelweg 15, NL-2629
JB Delft, The Netherlands
| | - Steffen Cornelius
- Materials
for Energy Conversion and Storage, Department of Chemical Engineering, Delft University of Technology, Van der Maasweg 9, NL-2629HZ Delft, The Netherlands
- Fraunhofer
Institute for Organic Electronics, Electron
Beam and Plasma Technology (FEP), Winterbergstrasse 28, 01277 Dresden, Germany
| | - Stephan W. H. Eijt
- Fundamental
Aspects of Materials and Energy, Department of Radiation Science and
Technology, Faculty of Applied Sciences, Delft University of Technology, Mekelweg 15, NL-2629
JB Delft, The Netherlands
| | - Bernard Dam
- Materials
for Energy Conversion and Storage, Department of Chemical Engineering, Delft University of Technology, Van der Maasweg 9, NL-2629HZ Delft, The Netherlands
| |
Collapse
|
22
|
Liu X, Zhang P, Wang B, Cao X, Jin S, Yu R. Study of Interaction Mechanism between Positrons and Ag Clusters in Dilute Al-Ag Alloys at Low Temperature. Materials (Basel) 2021; 14:1451. [PMID: 33809744 DOI: 10.3390/ma14061451] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/09/2021] [Revised: 03/09/2021] [Accepted: 03/12/2021] [Indexed: 11/17/2022]
Abstract
The microstructural evolution of dilute Al–Ag alloys in its early aging stage and at low temperatures ranging from 15 K to 300 K was studied by the combined use of Positron annihilation lifetime spectroscopy (PALS), high resolution transmission electron microscopy (HRTEM), and positron annihilation Coincidence Doppler broadening (CDB) techniques. It is shown that at low temperatures below 200 K, an Ag–vacancy complex is formed in the quenched alloy, and above 200 K, it decomposes into Ag clusters and monovacancies. Experimental and calculation results indicate that Ag clusters in Al–Ag alloys can act as shallow trapping sites, and the positron trapping rate is considerably enhanced by a decreasing measurement temperature.
Collapse
|
23
|
Das AK, Mukherjee S, R SS, Nair AS, Bhandary S, Chopra D, Sanyal D, Pathak B, Mandal S. Defects Engineering on Ceria and C-C Coupling Reactions Using [Au 11(PPh 3) 7I 3] Nanocluster: A Combined Experimental and Theoretical Study. ACS Nano 2020; 14:16681-16688. [PMID: 33253533 DOI: 10.1021/acsnano.0c03010] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [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
Ligand protected atom-precise gold-based catalysts have been utilized in many essential chemical processes, but their mechanism and the fate of the catalyst during reaction are still unrevealed. Atom-precise cluster without ligands are thus highly desirable to maximize atom efficiency, but making these in solution phase is challenging. In this scenario, catalysts with dispersion on oxide support are highly desirable to understand the role of metal core during catalytic reaction. Here, we report the synthesis of Au11(PPh3)7I3 cluster that consists of an incomplete icosahedron core. During its impregnation process on CeO2 support, all of the ligands were removed from the kernel and the Au11 kernel fits into the defects of ceria (embedded onto the oxygen vacancy of ceria (111) plane). This Au11@CeO2 has high atom efficiency and catalytic activity for Ullmann-type C-C homocoupling reactions for electron rich substrates. Density functional theory calculations showed that hexagonal arrangements of Au11 kernel on (111) plane of CeO2 is the most stable one. Theoretical calculations also proved that the atop gold atom has more favorable interaction with phenyl iodide than the second layer gold atoms of the Au11@CeO2. This demonstrated that the present catalyst mimics the single-atom catalyst-like behavior in facilitating the coupling reactions.
Collapse
Affiliation(s)
- Anish Kumar Das
- School of Chemistry, Indian Institute of Science Education and Research Thiruvananthapuram, Thiruvananthapuram, Kerala 695551, India
| | - Sayani Mukherjee
- School of Chemistry, Indian Institute of Science Education and Research Thiruvananthapuram, Thiruvananthapuram, Kerala 695551, India
| | - Sreehari S R
- School of Chemistry, Indian Institute of Science Education and Research Thiruvananthapuram, Thiruvananthapuram, Kerala 695551, India
| | - Akhil S Nair
- School of Basic Science, Indian Institute of Technology, Indore, Madhya Pradesh 453552, India
| | - Subhrajyoti Bhandary
- School of Chemistry, Indian Institute of Science Education and Research Bhopal, Bhopal, Madhya Pradesh 462066, India
| | - Deepak Chopra
- School of Chemistry, Indian Institute of Science Education and Research Bhopal, Bhopal, Madhya Pradesh 462066, India
| | - Dirtha Sanyal
- Variable Energy Cyclotron Centre, HBNI, 1/AF Bidhannagar, Kolkata 700064, India
| | - Biswarup Pathak
- School of Basic Science, Indian Institute of Technology, Indore, Madhya Pradesh 453552, India
| | - Sukhendu Mandal
- School of Chemistry, Indian Institute of Science Education and Research Thiruvananthapuram, Thiruvananthapuram, Kerala 695551, India
| |
Collapse
|
24
|
Zhou B, Chen L, Li C, Qi N, Chen Z, Su X, Tang X. Significant Enhancement in the Thermoelectric Performance of Aluminum-Doped ZnO Tuned by Pore Structure. ACS Appl Mater Interfaces 2020; 12:51669-51678. [PMID: 33151683 DOI: 10.1021/acsami.0c16506] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [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
In this paper, 2 atom % Al-doped ZnO (AZO) was prepared by the co-precipitation method together with sparking plasma sintering (SPS) treatment. The as-synthesized AZO powders show the morphology of hollow hexagonal towers, which result in a high porosity of 50.6% in the bulk sample consolidated by SPS sintering at 400 °C, and the porosity decreases gradually with increasing sintering temperature up to 1000 °C. Positron annihilation measurements reveal that even after sintering at 1000 °C, there are still a considerable number of small pores. A high electrical conductivity of 3 × 105 S m-1 is achieved at room temperature for the AZO sample sintered at 1000 °C, while the absolute values of Seebeck coefficient keep at relatively high values between 59 and 144 μV K-1 in the measurement temperature range of 27-500 °C, leading to a high power factor of 3.4 × 10-3 W m-1 K-2. On the other hand, the pores in AZO act as strong phonon scattering centers, and an extremely low thermal conductivity of 1.5 W m-1 K-1 measured at room temperature is obtained for AZO sintered at 400 °C. Due to the residual pores in the 1000 °C-sintered sample, the thermal conductivity is still relatively low. As a result, a maximum ZT of 0.275 measured at 500 °C is obtained in this sample, which is the highest ZT reported for ZnO around this temperature.
Collapse
Affiliation(s)
- Bo Zhou
- Hubei Nuclear Solid Physics Key Laboratory, Department of Physics, Wuhan University, Wuhan 430072, China
- Department of Radiotherapy, Henan Provincial People's Hospital, People's Hospital of Zhengzhou University, Zhengzhou, Henan 450003, China
| | - Lili Chen
- Hubei Nuclear Solid Physics Key Laboratory, Department of Physics, Wuhan University, Wuhan 430072, China
| | - Chongyang Li
- College of Electric Power, North China University of Water Resources and Electric Power, Zhengzhou 450045, China
| | - Ning Qi
- Hubei Nuclear Solid Physics Key Laboratory, Department of Physics, Wuhan University, Wuhan 430072, China
| | - Zhiquan Chen
- Hubei Nuclear Solid Physics Key Laboratory, Department of Physics, Wuhan University, Wuhan 430072, China
| | - Xianli Su
- State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070, China
| | - XinFeng Tang
- State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070, China
| |
Collapse
|
25
|
Zhang Q, Gu B, Wu Y, Zhu T, Fang T, Yang Y, Liu J, Ye B, Zhao X. Evolution of the Intrinsic Point Defects in Bismuth Telluride-Based Thermoelectric Materials. ACS Appl Mater Interfaces 2019; 11:41424-41431. [PMID: 31612710 DOI: 10.1021/acsami.9b15198] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
In polycrystalline bismuth telluride-based thermoelectric materials, mechanical-deformation-induced donor-like effects can introduce a high concentration of electrons to change the thermoelectric properties through the evolution of intrinsic point defects. However, the evolution law of these point defects during sample preparation remains elusive. Herein, we systematically investigate the evolution of intrinsic point defects in n-type Bi2Te3-based materials from the perspective of thermodynamics and kinetics, in combination with positron annihilation measurement. It is found that not only the mechanical deformation but also the sintering temperature is vital to the donor-like effect. The mechanical deformation can promote the formation of cation vacancies and facilitate the donor-like effect, and the sintering process can provide excess energy for Bi antisite atoms to surmount the diffusion potential barrier. This work provides us a better understanding of the evolution law of intrinsic point defects in Bi2Te3-based alloys and guides us to control the carrier concentration by manipulating intrinsic point defects.
Collapse
Affiliation(s)
- Qi Zhang
- State Key Laboratory of Silicon Materials, and School of Materials Science and Engineering , Zhejiang University , Hangzhou 310027 , China
| | - Bingchuan Gu
- State Key Laboratory of Particle Detection and Electronics , University of Science & Technology of China , Hefei 230026 , Anhui , China
| | - Yehao Wu
- State Key Laboratory of Silicon Materials, and School of Materials Science and Engineering , Zhejiang University , Hangzhou 310027 , China
| | - Tiejun Zhu
- State Key Laboratory of Silicon Materials, and School of Materials Science and Engineering , Zhejiang University , Hangzhou 310027 , China
| | - Teng Fang
- State Key Laboratory of Silicon Materials, and School of Materials Science and Engineering , Zhejiang University , Hangzhou 310027 , China
| | - Yuxi Yang
- State Key Laboratory of Silicon Materials, and School of Materials Science and Engineering , Zhejiang University , Hangzhou 310027 , China
| | - Jiandang Liu
- State Key Laboratory of Particle Detection and Electronics , University of Science & Technology of China , Hefei 230026 , Anhui , China
| | - Bangjiao Ye
- State Key Laboratory of Particle Detection and Electronics , University of Science & Technology of China , Hefei 230026 , Anhui , China
| | - Xinbing Zhao
- State Key Laboratory of Silicon Materials, and School of Materials Science and Engineering , Zhejiang University , Hangzhou 310027 , China
| |
Collapse
|
26
|
Liu J, Qi N, Zhou B, Chen Z. Exceptionally High CO 2 Capture in an Amorphous Polymer with Ultramicropores Studied by Positron Annihilation. ACS Appl Mater Interfaces 2019; 11:30747-30755. [PMID: 31362490 DOI: 10.1021/acsami.9b07015] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
A series of amorphous melamine-based polymer networks synthesized by Schiff base chemistry (SNW) were successfully prepared by varying the strut length. The pore structure was analyzed by gas adsorption and positron annihilation methods. Positron lifetime measurements indicate the existence of ultramicropores and also larger mesopores in the SNW materials. The sizes of micropores and mesopores are almost the same in these samples, which are about 0.7 and 16.5 nm, respectively. The relative number of micropores increases in the order of SNW-1 < SNW-2 < SNW-3, while the number of mesopores increases in the reverse order. N2 adsorption/desorption measurements also reveal micropores and mesopores in these materials. However, it gives an underestimation of the micropore volume. Benefiting from the abundant nitrogen content and high microporosity, the SNW materials exhibit exceptionally high CO2 capture ability, which reaches a maximum value of 18.3 wt % in SNW-3 at 273 K and 1 bar, followed by SNW-2 and SNW-1. This order is exactly the same as the order of micropore volume revealed by positron annihilation measurement, suggesting that micropores play a crucial role in the CO2 uptake. Our results show that positron can provide more precise information about the structure of micropores and thus can offer an accurate prediction for the adsorption capacity of complex porous materials.
Collapse
Affiliation(s)
- Junjie Liu
- Hubei Nuclear Solid Physics Key Laboratory, Department of Physics , Wuhan University , Wuhan 430072 , People's Republic of China
| | - Ning Qi
- Hubei Nuclear Solid Physics Key Laboratory, Department of Physics , Wuhan University , Wuhan 430072 , People's Republic of China
| | - Bo Zhou
- Hubei Nuclear Solid Physics Key Laboratory, Department of Physics , Wuhan University , Wuhan 430072 , People's Republic of China
| | - Zhiquan Chen
- Hubei Nuclear Solid Physics Key Laboratory, Department of Physics , Wuhan University , Wuhan 430072 , People's Republic of China
| |
Collapse
|
27
|
Zhang X, Xiong B, Li J, Qian L, Liu L, Liu Z, Fang P, He C. Dependence of Dye Molecules Adsorption Behaviors on Pore Characteristics of Mesostructured MOFs Fabricated by Surfactant Template. ACS Appl Mater Interfaces 2019; 11:31441-31451. [PMID: 31370391 DOI: 10.1021/acsami.9b06517] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
In this work, mesostructured metal-organic frameworks (MOFs) of MIL-101-Crs with different specific surface areas were synthesized successfully under solvothermal conditions using cationic surfactant cetyltrimethyl ammonium bromide (CTAB) as a structural template. It was found that crystallinity degrees, specific surface areas, and pore size distributions strongly depended on the loading of CTAB. Nitrogen adsorption and positron annihilation lifetime spectroscopy (PALS) results showed that the mean mesopore size increased with loading more CTAB due to the formation of larger templated mesopores. Although Langmuir adsorption of both methylene blue (MB) and methyl orange (MO) was confirmed in MIL-101-Crs, the experimental results showed different adsorption behaviors for them depending on the dye molecular size, pore structure, and charge properties of dye molecules/MOFs in solution. The MB molecules were found to be mainly adsorbed in the interspaces between grains and the templated mesopores, whereas the MO molecules were adsorbed in the inherent pores as well as the templated ones in MOFs due to the unsaturated metal sites' electrostatic attraction on them. Remarkably, MO adsorption capacity was observed to be proportional to the specific surface area, which allowed one to get a good linear fitting of experimental data. Interestingly, the good consistence between the fitting experimental parameter, that is, the number of adsorbed MO-s per unit specific surface area, and the calculated one according to our rough estimation strongly suggests that MO-s are electrostatically attracted and rotating around the unsaturated metal sites on MOFs' inner surfaces, which exclude other MO-s to be adsorbed around due to the "hindering effect" of the rotating motion.
Collapse
Affiliation(s)
- Xiaowei Zhang
- Key Laboratory of Nuclear Solid State Physics Hubei Province, School of Physics and Technology , Wuhan University , Wuhan 430072 , China
| | - Bangyun Xiong
- School of Materials Science and Energy Engineering , Foshan University , Foshan 528000 , China
| | - Jingjing Li
- School of Materials Science and Energy Engineering , Foshan University , Foshan 528000 , China
| | - Libing Qian
- Key Laboratory of Nuclear Solid State Physics Hubei Province, School of Physics and Technology , Wuhan University , Wuhan 430072 , China
| | - Lei Liu
- Key Laboratory of Nuclear Solid State Physics Hubei Province, School of Physics and Technology , Wuhan University , Wuhan 430072 , China
| | - Zhe Liu
- Key Laboratory of Nuclear Solid State Physics Hubei Province, School of Physics and Technology , Wuhan University , Wuhan 430072 , China
| | - Pengfei Fang
- Key Laboratory of Nuclear Solid State Physics Hubei Province, School of Physics and Technology , Wuhan University , Wuhan 430072 , China
| | - Chunqing He
- Key Laboratory of Nuclear Solid State Physics Hubei Province, School of Physics and Technology , Wuhan University , Wuhan 430072 , China
| |
Collapse
|
28
|
Panda S, Vinodkumar P, Madhusoodanan U, Panigrahi BS. Probing the optical properties and luminescence mechanism of a UV-emitting SrBPO 5 :Ce 3+ phosphor. LUMINESCENCE 2019; 34:887-894. [PMID: 31328361 DOI: 10.1002/bio.3687] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2018] [Revised: 05/13/2019] [Accepted: 07/01/2019] [Indexed: 11/08/2022]
Abstract
Ce-doped (1 × 10-5 to 3.0 mol%) SrBPO5 phosphors were synthesized using a conventional solid-state reaction route at 1273 K in an air atmosphere. Phase and morphology of the samples were studied from powder X-ray diffraction (XRD) patterns and scanning electron microscope (SEM) micrographs, respectively. The band gap energies of the pure and Ce-doped SrBPO5 phosphors were calculated from the recorded diffuse reflectance spectra. Photoluminescence (PL) and Ce3+ lifetime were recorded at 300 and 77 K. Photoluminescence lifetime measurements revealed two-lifetime values for Ce3+ at both 300 K (17 and 36 nsec) and 77 K (12 and 30 nsec), suggesting the presence of two different environments around Ce3+ . Time-resolved emission spectroscopy (TRES) studies confirmed the presence of Ce3+ in two different environments. In addition, SrBPO5 :Ce exhibited intense UV emission, signifying its possible use as an efficient sensitizer for solid-state lighting applications. The effect of γ-irradiation on PL was also determined. Thermally stimulated luminescence (TSL) glow curves of the γ-irradiated phosphor, along with trap parameters, dose-response, and the possible TSL mechanism were also investigated. Positron annihilation lifetime spectroscopy was carried out to probe defects present in undoped and Ce-doped SrBPO5 .
Collapse
Affiliation(s)
- Sitakanta Panda
- Health Safety & Environment Group, Indira Gandhi Centre for Atomic Research, Homi Bhabha National Institute, Kalpakkam, 603102, Tamil Nadu, India
| | - P Vinodkumar
- Health Safety & Environment Group, Indira Gandhi Centre for Atomic Research, Homi Bhabha National Institute, Kalpakkam, 603102, Tamil Nadu, India
| | - U Madhusoodanan
- Health Safety & Environment Group, Indira Gandhi Centre for Atomic Research, Kalpakkam, 603102, Tamil Nadu, India
| | - B S Panigrahi
- Health Safety & Environment Group, Indira Gandhi Centre for Atomic Research, Homi Bhabha National Institute, Kalpakkam, 603102, Tamil Nadu, India
| |
Collapse
|
29
|
Budaj M, Michalski A, Miśkowiak B, Filipecka K, Mandecka S. [Study of the structure of contact lenses using PALS, MIR and Raman spectroscopy in the regard of safety of persons exposed to ionizing radiation]. Polim Med 2019; 48:5-9. [PMID: 30484288 DOI: 10.17219/pim/96287] [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] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Among patients and health professionals who are exposed to ionizing radiation during diagnostic and therapeutic procedures, refractive errors are common and soft contact lenses are widely used to correct them. Changes in the inner structure of contact lens may influence the safety of its usage through modification of its water content or oxygen accessibility to cornea. Therefore, analysis of impact of external factors, therein ionizing radiation used in medicine, on contact lenses parameters is necessary, particularly to compare the presence of free volume gaps in the structure of the polymer soft contact lenses. Possible change in dimensions or quantity of free volume gaps in the structure of the material caused by the exposure to ionizing radiation may have negative influence on oxygen permeability. To prevent such process, different means could be used, i.a., positron annihilation lifetime spectroscopy (PALS), Raman spectroscopy and mid-infrared spectroscopy (MIR). Use of contact lenses which reduce transport of oxygen to cornea increases the risk of corneal hypoxia - one of the possible complications of using contact lenses. Research on effects of different types of ionizing radiation (X-ray, gamma, beta) on materials used in production of contact lenses is vital because of the connection of this issue with the safety of contact lenses wearers. Such research can also shed light on the problem of safe use of contact lenses by persons exposed to ionizing radiation.
Collapse
Affiliation(s)
- Mariusz Budaj
- Zakład Optometrii, Katedra Chorób Oczu i Optometrii, Uniwersytet Medyczny im. Karola Marcinkowskiego w Poznaniu, Polska
| | - Andrzej Michalski
- Klinika Chorób Oczu, Katedra Chorób Oczu i Optometrii, Uniwersytet Medyczny im. Karola Marcinkowskiego w Poznaniu, Polska
| | - Bogdan Miśkowiak
- Zakład Optometrii, Katedra Chorób Oczu i Optometrii, Uniwersytet Medyczny im. Karola Marcinkowskiego w Poznaniu, Polska.,Wyższa Szkoła Zdrowia, Urody i Edukacji w Poznaniu, Polska
| | - Katarzyna Filipecka
- Zakład Badań Strukturalnych i Fizyki Medycznej, Instytut Fizyki, Wydział Matematyczno-Przyrodniczy, Akademia im Jana Długosza w Częstochowie, Polska
| | - Sylwia Mandecka
- Zakład Radioterapii, Wojewódzki Szpital Specjalistyczny im. Najświętszej Maryi Panny w Częstochowie, Polska
| |
Collapse
|
30
|
Shu G, Zhao J, Zheng X, Xu M, Liu Q, Zeng M. Modification of Montmorillonite with Polyethylene Oxide and Its Use as Support for Pd 0 Nanoparticle Catalysts. Polymers (Basel) 2019; 11:E755. [PMID: 31035647 DOI: 10.3390/polym11050755] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2019] [Revised: 04/18/2019] [Accepted: 04/18/2019] [Indexed: 12/26/2022] Open
Abstract
In this study, montmorillonite (MMT) was modified by intercalating polyethylene oxide (PEO) macromolecules between the interlayer spaces in an MMT-water suspension system. X-ray diffraction results revealed that the galleries of MMT were expanded significantly after intercalation of different loading of PEO. MMT/PEO 80/20 composite was chosen as the support platform for immobilization of Pd species in preparing novel heterogeneous catalysts. After immobilization of Pd species, the interlayer spacing of MMT/PEO (80/20) (1.52 nm) was further increased to 1.72 nm (Pd2+@MMT/PEO) and 1.73 nm (Pd0@MMT/PEO), confirming the well-immobilization of the Pd species in the interlayer spaces of PEO-modified MMT. High-resolution transmission electron microscopy (HR-TEM) observation results confirmed that Pd nanoparticles were confined inside the interlayer space of MMT and/or dispersed well on the outer surface of MMT. The conversion of Pd2+ to Pd0 species was evidenced by binding energy characterization with X-ray photo electron spectroscopy (XPS). The microstructure variation caused by the Pd immobilization was sensitively detected by positron annihilation lifetime spectroscopy (PALS) studies. The prepared Pd0@MMT/PEO (0.2/80/20) catalytic composite exhibits good thermal stability up to around 200 °C, and it showed high activities for Heck reactions between aryl iodides and butyl acrylates and could be recycled for five times. The correlations between the microstructure and properties of the Pd@MMT/PEO catalytic composites were discussed.
Collapse
|
31
|
Sun H, Lei P, Ran G, Wang H, Zheng J, Zhang Y, Wang Z, Qiu S. Ion Irradiation-Induced Microstructural Evolution of Ni⁻Mo⁻Cr Low Alloy Steels. Materials (Basel) 2018; 11:E2268. [PMID: 30428609 DOI: 10.3390/ma11112268] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/21/2018] [Revised: 11/01/2018] [Accepted: 11/09/2018] [Indexed: 11/17/2022]
Abstract
As leading candidates of sheet steels for advanced nuclear reactors, three types of Ni–Mo–Cr high-strength low alloy (HSLA) steels named as CNST1, CNST2 and CNSS3 were irradiated by 400 keV Fe+ with peak fluence to 1.4 × 1014, 3.5 × 1014 and 7.0 × 1014 ions/cm2, respectively. The distribution and morphology of the defects induced by the sample preparation method and Fe+ irradiation dose were investigated by transmission electron microscopy (TEM) and positron-annihilation spectroscopy (PAS). TEM samples were prepared with two methods, i.e., a focused ion beam (FIB) technique and the electroplating and twin-jet electropolishing (ETE) method. Point defects and dislocation loops were observed in CNST1, CNST2 and CNSS3 samples prepared via FIB. On the other hand, samples prepared via the ETE method revealed that a smaller number of defects was observed in CNST1, CNST2 and almost no defects were observed in CNST3. It is indicated that artifact defects could be introduced by FIB preparation. The PAS S-W plots showed that the existence of two types of defects after ion implantation included small-scale defects such as vacancies, vacancy clusters, dislocation loops and large-sized defects. The S parameter of irradiated steels showed a clear saturation in PAS response with increasing Fe+ dose. At the same irradiation dose, higher values of the S-parameter were achieved in CNST1 and CNST2 samples when compared to that in CNSS3 samples. The mechanism and evolution behavior of irradiation-induced defects were analyzed and discussed.
Collapse
|
32
|
Xu M, Zhao J, Shu G, Liu Q, Zeng M. Heterogeneous Catalytic Composites from Palladium Nanoparticles in Montmorillonite Intercalated with Poly (Vinyl Pyrrolidone) Chains. Polymers (Basel) 2018; 10:E669. [PMID: 30966703 DOI: 10.3390/polym10060669] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2018] [Revised: 06/11/2018] [Accepted: 06/13/2018] [Indexed: 11/21/2022] Open
Abstract
In this study, poly (vinyl pyrrolidone) (PVP) chains intercalated montmorillonite (MMT) matrices has been demonstrated as an excellent scaffolding material for the immobilization of palladium (Pd) nanoparticles to prepare efficient heterogeneous catalysts for Heck reactions. Multiple layers (up to four) of PVP chains can intercalate the interlayer space of the MMT, resulting in an increase therein from 1.25 to 3.22 nm. MMT/PVP with PVP loading (20%) was selected as the platform for the immobilization of Pd. The in-situ reduction of the chelated Pd2+ into Pd0 in the interlayer space of MMT/PVP composite could be easily achieved. For the prepared Pd@MMT/PVP catalytic composite, a unique maze-like microstructure of Pd nanoparticles tightly encaged by PVP chains and by lamellae of layered silica has been detected by high resolution transmission electron microscopy (HR-TEM) and X-ray diffraction (XRD). Furthermore, the microstructure is well elucidated in molecular level by positron annihilation lifetime analysis of the Pd@MMT/PVP catalytic composite. The prepared Pd@MMT/PVP catalysts were highly active for the Heck coupling reactions between aromatic halides and alkenes, and could be recycled 9 times without significant decreases in coupling yields. The excellent comprehensive catalytic performances of the Pd@MMT/PVP catalytic composites are mainly attributed to their unique maze-like microstructure.
Collapse
|
33
|
Zeng M, Wang Y, Liu Q, Yuan X, Zuo S, Feng R, Yang J, Wang B, Qi C, Lin Y. Encaging Palladium Nanoparticles in Chitosan Modified Montmorillonite for Efficient, Recyclable Catalysts. ACS Appl Mater Interfaces 2016; 8:33157-33164. [PMID: 27934141 DOI: 10.1021/acsami.6b09895] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Metal nanoparticles, once supported by a suitable scaffolding material, can be used as highly efficient heterogeneous catalysts for numerous organic reactions. The challenge, though, is to mitigate the continuous loss of metals from the supporting materials as reactions proceed, so that the catalysts can be recycled multiple times. Herein, we combine the excellent chelating property of chitosan (CS) and remarkable stability of montmorillonite (MMT) into a composite material to support metal catalysts such as palladium (Pd). The in situ reduction of Pd2+ into Pd0 in the interstices of MMT/CS composites effectively encages the Pd0 nanoparticles in the porous matrices, while still allowing for reactant and product molecules of relatively small sizes to diffuse in and out the matrices. The prepared Pd0@MMT/CS catalysts are highly active for the Heck reactions of aromatic halides and alkenes, and can be recycled 30 times without significant loss of activities. Positron annihilation lifetime analysis and other structural characterization methods are implemented to elucidate the unique compartmentalization of metal catalysts in the composite matrices. As both CS and MMT are economical and abundant materials in nature, this approach may facilitate a versatile platform for developing highly recyclable, heterogeneous catalysts containing metal nanoparticles.
Collapse
Affiliation(s)
- Minfeng Zeng
- Zhejiang Key Laboratory of Alternative Technologies for Fine Chemicals Process, Shaoxing University , Shaoxing 312000, China
| | - Yudong Wang
- Zhejiang Key Laboratory of Alternative Technologies for Fine Chemicals Process, Shaoxing University , Shaoxing 312000, China
| | - Qi Liu
- Zhejiang Key Laboratory of Alternative Technologies for Fine Chemicals Process, Shaoxing University , Shaoxing 312000, China
| | - Xia Yuan
- Zhejiang Key Laboratory of Alternative Technologies for Fine Chemicals Process, Shaoxing University , Shaoxing 312000, China
| | - Shufeng Zuo
- Zhejiang Key Laboratory of Alternative Technologies for Fine Chemicals Process, Shaoxing University , Shaoxing 312000, China
| | - Ruokun Feng
- Zhejiang Key Laboratory of Alternative Technologies for Fine Chemicals Process, Shaoxing University , Shaoxing 312000, China
| | - Jing Yang
- Institute of High Energy Physics, The Chinese Academy of Science , Beijing 100049, China
| | - Baoyi Wang
- Institute of High Energy Physics, The Chinese Academy of Science , Beijing 100049, China
| | - Chenze Qi
- Zhejiang Key Laboratory of Alternative Technologies for Fine Chemicals Process, Shaoxing University , Shaoxing 312000, China
| | - Yao Lin
- Polymer Program, Institute of Materials Science and Department of Chemistry, University of Connecticut , Storrs, Connecticut 06269, United States
| |
Collapse
|