1
|
Samanta S, Maity A, Chatterjee A, Giri S, Chakravorty D. Crossover of positive and negative magnetoconductance in composites of nanosilica glass containing dual transition metal oxides. RSC Adv 2021; 11:16106-16121. [PMID: 35481159 PMCID: PMC9030562 DOI: 10.1039/d1ra02215f] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2021] [Accepted: 04/23/2021] [Indexed: 11/23/2022] Open
Abstract
A facile sol-gel approach to prepare composites of nanosilica glass containing dual transition metal oxides with compositions xCoO·(20 - x)NiO·80SiO2 comprising x values 5 (NC-1), 10 (NC-2) and 15 (NC-3) within hexagonal pores of SBA-15 template has been demonstrated. The synergistic effect of dual transition metal oxide ions on MD properties and crossover of positive and negative magnetoconductance phenomena were observed in these nanocomposite systems. The physical origin of magnetoconductance switching is explained based on the factors: nanoconfinement effect, wave-function shrinkage and spin polarized electron hopping. DFT calculations were performed to understand the structural correlation of the nanoconfined system. The static (dc) and dynamic (ac) responses of magnetization revealed the spin-glass behaviour of the investigated samples. Both scaling law and Vogel-Fulcher law provide a satisfactory fit to our experimental results which are considered as a salient feature of the spin-glass system. Our studies indicate the possibilities of fabricating magnetically controlled multifunctional devices.
Collapse
Affiliation(s)
- Subha Samanta
- School of Materials Science, Indian Association for the Cultivation of Science 2A and 2B Raja S.C. Mallick Road Kolkata 700032 India +91 33 2473 2805 +91 33 2473 4971 (Ext 1580)
- School of Physical Science, Indian Association for the Cultivation of Science 2A and 2B Raja S.C. Mallick Road Kolkata 700032 India
| | - Anupam Maity
- School of Materials Science, Indian Association for the Cultivation of Science 2A and 2B Raja S.C. Mallick Road Kolkata 700032 India +91 33 2473 2805 +91 33 2473 4971 (Ext 1580)
- Department of Physics, Jadavpur University 188 Raja S.C. Mallick Road Kolkata 700032 India
| | - Alorika Chatterjee
- School of Physical Science, Indian Association for the Cultivation of Science 2A and 2B Raja S.C. Mallick Road Kolkata 700032 India
| | - Saurav Giri
- School of Physical Science, Indian Association for the Cultivation of Science 2A and 2B Raja S.C. Mallick Road Kolkata 700032 India
| | - Dipankar Chakravorty
- School of Materials Science, Indian Association for the Cultivation of Science 2A and 2B Raja S.C. Mallick Road Kolkata 700032 India +91 33 2473 2805 +91 33 2473 4971 (Ext 1580)
| |
Collapse
|
2
|
Maximiano P, Durães L, Simões P. Overview of Multiscale Molecular Modeling and Simulation of Silica Aerogels. Ind Eng Chem Res 2019. [DOI: 10.1021/acs.iecr.9b03781] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Affiliation(s)
- Pedro Maximiano
- CIEPQPF, Department of Chemical Engineering, University of Coimbra, Rua Sı́lvio de Lima, 3030-790 Coimbra, Portugal
| | - Luísa Durães
- CIEPQPF, Department of Chemical Engineering, University of Coimbra, Rua Sı́lvio de Lima, 3030-790 Coimbra, Portugal
| | - Pedro Simões
- CIEPQPF, Department of Chemical Engineering, University of Coimbra, Rua Sı́lvio de Lima, 3030-790 Coimbra, Portugal
| |
Collapse
|
3
|
Chen X, Eldred D, Liu J, Chiang H, Wang X, Rickard MA, Tu S, Cui L, LaBeaume P, Skinner K. Simultaneous In Situ Monitoring of Trimethoxysilane Hydrolysis Reactions Using Raman, Infrared, and Nuclear Magnetic Resonance (NMR) Spectroscopy Aided by Chemometrics and Ab Initio Calculations. APPLIED SPECTROSCOPY 2018; 72:1404-1415. [PMID: 29756466 DOI: 10.1177/0003702818774570] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Sol-gels are found in many different scientific fields and have very broad applications. They are often prepared by the hydrolysis and condensation of alkoxysilanes such as trimethoxysilanes, which are commonly used as precursors in the preparation of silsequioxanes via the sol-gel process. The reaction rates of such reactions are influenced by a wide range of experimental factors such as temperature, pH, catalyst, etc. In this study, we combined multiple in situ spectroscopic techniques to monitor the hydrolysis and partial condensation reactions of methyltrimethoxysilane and phenyltrimethoxysilane. A rich set of kinetics information on intermediate species of the hydrolysis reactions were obtained and used for kinetics modeling. Raman and nuclear magnetic resonance (NMR) spectroscopy provided the most information about hydrolysis and NMR provided the most information about condensation. A quantitative method based on Raman spectra to quantify the various transient intermediate hydrolysis products was developed using NMR as the primary method, which can be deployed in the field where it is impractical to carry out NMR measurements.
Collapse
Affiliation(s)
- Xiaoyun Chen
- 1 Analytical Sciences, The Dow Chemical Company, Midland, MI, USA
| | - Donald Eldred
- 2 Dow Performance Silicones, The Dow Chemical Company, Auburn, MI, USA
| | - Jing Liu
- 3 Process & Engineering Sciences, The Dow Chemical Company, Midland, MI, USA
| | - Hsu Chiang
- 3 Process & Engineering Sciences, The Dow Chemical Company, Midland, MI, USA
| | - Xianghuai Wang
- 2 Dow Performance Silicones, The Dow Chemical Company, Auburn, MI, USA
| | - Mark A Rickard
- 1 Analytical Sciences, The Dow Chemical Company, Midland, MI, USA
| | - Siyu Tu
- 3 Process & Engineering Sciences, The Dow Chemical Company, Midland, MI, USA
| | - Li Cui
- 4 Dow Electronic Materials, Marlborough, MA, USA
| | | | - Kwan Skinner
- 5 Dow Performance Silicones Process R&D, The Dow Chemical Company, Midland, MI, USA
| |
Collapse
|
4
|
Borba A, Vareda JP, Durães L, Portugal A, Simões PN. Spectroscopic characterization of silica aerogels prepared using several precursors – effect on the formation of molecular clusters. NEW J CHEM 2017. [DOI: 10.1039/c7nj01082f] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The structural and spectroscopic properties of silica aerogels were studied using complementary approaches, such as Fourier transform infrared spectroscopy and solid-state NMR spectroscopy.
Collapse
Affiliation(s)
- A. Borba
- CIEPQPF – Department of Chemical Engineering
- University of Coimbra
- P-3030-790 Coimbra
- Portugal
| | - J. P. Vareda
- CIEPQPF – Department of Chemical Engineering
- University of Coimbra
- P-3030-790 Coimbra
- Portugal
| | - L. Durães
- CIEPQPF – Department of Chemical Engineering
- University of Coimbra
- P-3030-790 Coimbra
- Portugal
| | - A. Portugal
- CIEPQPF – Department of Chemical Engineering
- University of Coimbra
- P-3030-790 Coimbra
- Portugal
| | - P. N. Simões
- CIEPQPF – Department of Chemical Engineering
- University of Coimbra
- P-3030-790 Coimbra
- Portugal
| |
Collapse
|
5
|
Fernández L, Pérez-Pla FF, Tuñón I, Llopis E. DFT Study on the Interaction of Tris(benzene-1,2-dithiolato)molybdenum Complex with Water. A Hydrolysis Mechanism Involving a Feasible Seven-Coordinate Aquomolybdenum Intermediate. J Phys Chem A 2016; 120:9636-9646. [PMID: 27933913 DOI: 10.1021/acs.jpca.6b10233] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In the present work, the reactivity of the tris(benzene-1,2-dithiolato)molybdenum complex ([Mo(bdt)3]) toward water is studied by means of the density functional theory (DFT). DFT calculations were performed using the M06, B3P86, and B3PW91 hybrid functionals for comparison purposes. The M06 method was employed to elucidate the reaction pathway, relative stability of the intermediate products, nature of the Mo-S bond cleavage, and electronic structure of the involved molybdenum species. This functional was also used to study the transference of electrons from the molybdenum center toward the ligands. The reaction pathway confirms that [Mo(bdt)3] undergoes hydrolysis, yielding dihydroxo-bis(benzene-1,2-dithiolato)molybdenum complex ([Mo(OH)2(bdt)2]) and benzenedithiol. The reaction takes place through seven transition structures, one of them involving an aquo seven-coordinate molybdenum intermediate stabilized by a lone pair (LP) LPO→LPMo hyperconjugative interaction. This heptacoordinate species allows understanding of the observed oxygen atom exchange between water and tertiary phosphines mediated by these complexes. Calculations also show that [Mo(C2H4S2)3] and [Mo(OH)2(C2H4S2)2] have d2 and d0 electronic configuration, and hence an electron pair must be transferred during the course of the hydrolysis. The frontier molecular orbital (FMO) analysis concludes that the electron pair is transferred in the rupture of the second Mo-S bond, from the occupied donating Mo dx2-y2 orbital to the unoccupied C2H4(SH)2 S-C σ* ligand orbital. This result is supported by the bond dissociation energy calculations, which demonstrate that the neutral dissociation of the second Mo-S bond is energetically the more favorable.
Collapse
Affiliation(s)
- Lorenzo Fernández
- Institut de Cíencia dels Materials (ICMUV) , c/Catedrático Beltrán 2, 46980, Valencia, Spain
| | - Francisco F Pérez-Pla
- Institut de Cíencia dels Materials (ICMUV) , c/Catedrático Beltrán 2, 46980, Valencia, Spain
| | - Iñaki Tuñón
- Departamento de Química Física, Universitat de València , Dr. Moliner 50, 46100, Burjassot, Valencia, Spain
| | - Elisa Llopis
- Institut de Cíencia dels Materials (ICMUV) , c/Catedrático Beltrán 2, 46980, Valencia, Spain
| |
Collapse
|
6
|
Borba A, Almangano M, Portugal AA, Patrício R, Simões PN. Methylsilsesquioxane-Based Aerogel Systems-Insights into the Role of the Formation of Molecular Clusters. J Phys Chem A 2016; 120:4079-88. [PMID: 27213224 DOI: 10.1021/acs.jpca.6b04196] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Condensed clusters of hydrolyzed methyltrimethoxysilane (MTMS) were studied using two complementary approaches: (i) Fourier transform infrared (FTIR) spectroscopy was applied along with the hydrolysis and condensation stages of a sol-gel process from the condensation of colloidal suspension of nanoparticles to the solid phase of bulk material; (ii) density functional theory calculations of energies, structural and vibrational data of pertinent MTMS hydrolysis products, specifically, methylsilanetriol-based species with different number of silicon atoms (from two to eight atoms) and different structures/conformations (linear, cyclic, and cage, in a total of 13 structures), were performed at B3LYP/6-311+G(d,p) level of theory. The calculated infrared spectra show two distinct Si-O-Si stretch vibration bands for models of caged structures. The higher-frequency IR band at ca. 1120 cm(-1) is derived from the antisymmetric Si-O-Si stretch vibration mode, while the lower-frequency band at 1035 cm(-1) is due to the symmetric Si-O-Si stretch and is characteristic of the cyclic clusters, being absent in highly symmetric cage structures. The calculated versus the experimental FTIR spectra of poly(methylsilsesquioxane) (PMSQ) dried aerogel in KBr pellet show that cage/cyclic-like structures prevail over ladder structures (linear) in actual PMSQ.
Collapse
Affiliation(s)
- A Borba
- CIEPQPF-Department of Chemical Engineering, University of Coimbra , 3030-790 Coimbra, Portugal
| | - M Almangano
- CIEPQPF-Department of Chemical Engineering, University of Coimbra , 3030-790 Coimbra, Portugal.,Active Aerogels, IPN , Edifício C, Rua Pedro Nunes, 3030-199 Coimbra, Portugal
| | - A A Portugal
- CIEPQPF-Department of Chemical Engineering, University of Coimbra , 3030-790 Coimbra, Portugal
| | - R Patrício
- Active Aerogels, IPN , Edifício C, Rua Pedro Nunes, 3030-199 Coimbra, Portugal
| | - P N Simões
- CIEPQPF-Department of Chemical Engineering, University of Coimbra , 3030-790 Coimbra, Portugal
| |
Collapse
|
7
|
Firmino TR, Riveros JM. An unprecedented gas-phase condensation reaction mediated by a bissilylated chloronium ion intermediate. NEW J CHEM 2016. [DOI: 10.1039/c5nj02250a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Gas phase Cl2Si(OH)+ ions undergo an unusual condensation reaction with SiCl4 to yield Cl3SiOSiCl2+ ions that by progressive hydrolysis or solvolysis give rise to a large variety of siloxane type moieties.
Collapse
|