Khasa, S. and Seth, V. P. and Gahlot, P. S. and Agarwal, A. and Gupta, S. K. (2006) Effect of cobalt ions on the EPR and dc conductivity in vanadyl doped CoO-M2O-B2O3 (M=Li, K) glasses. Physics and Chemistry of Glasses , 47 (4). pp. 371-376. ISSN 0031-9090
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Abstract
Glasses having the composition xCoO.(0(.)30-x)M2O.0(.)70B(2)O(3) (M=Li, K) have been prepared over the range 0(.)00 <= x <= 0(.)15 containing 1(.)0 and 2(.)0 mol% of V2O5, Spin-Hamiltonian parameters, dipolar hyperfine coupling parameter, P, and Fermi contact interaction term, K, of the VO2+ ions have been calculated. It is found the V4+ ions in these glasses exist as VO2+ in octahedral coordination with a tetragonal distortion. Results suggest that hyperfine spectra on vanadium are not observed when the amount of CoO exceeds a certain value, which depends on the type of alkali and the amount Of V2O5. The 3dxy orbital in the vanadium ion expands and the tetragonal distortion around vanadium ion increases with the increase in the CoO.M2O ratio. There is virtually no change in the microscopic structure around vanadium due to annealing or when Li2O is replaced by K2O. The d.c. conductivity decreases when Li2O is replaced by K2O, keeping the concentration of CoO and B2O3 constant. Addition of CoO to the sample shows a "blocking effect" on the overall mobility of alkali ions. As a result the conductivity of the sample decreases with increase in COO:M2O ratio.
| Item Type: | Article |
|---|---|
| Subjects: | Materials Science Applied Physics/Condensed Matter Physics > Physics of Fluids and Plasmas Nanoscience/ Nanotechnology Physical Chemistry/Chemical Physics |
| Divisions: | UNSPECIFIED |
| Depositing User: | Mr. Yogesh Joshi |
| Date Deposited: | 22 Aug 2019 08:07 |
| Last Modified: | 22 Aug 2019 08:07 |
| URI: | http://npl.csircentral.net/id/eprint/4049 |
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