Influence of mixed alkali on the spectral properties of vanadyl ions doped xNa{sub 2}O-(30 - x)K{sub 2}O-60B{sub 2}O{sub 3} glasses-an EPR and optical study
- Department of Physics, Indian Institute of Science, C.V. Raman Avenue, Bangalore 560 012 (India)
- Department of Physics, Sri Venkateswara University, Tirupati 517 502 (India)
Electron paramagnetic resonance (EPR) and optical investigations have been performed in the mixed alkali borate xNa{sub 2}O-(30 - x)K{sub 2}O-60B{sub 2}O{sub 3} (5 {<=} x {<=} 25) glasses doped with 10 mol% of vanadyl ions in order to look for the effect of 'mixed alkalis' on the spectral properties of the glasses. The observed EPR spectra have structures for x > 5 mol% which are characteristic of a hyperfine interaction arising from an unpaired electron with the {sup 51}V nucleus and it builds up in intensity as x increases. It is observed that the mixed alkali play a significant role in accommodating the vanadyl ions in these mixed alkali glasses and for x > 5 mol%, shows a well resolved hyperfine structure typical for isolated VO{sup 2+} ions. The spin-Hamiltonian parameters (g and A), the dipolar hyperfine coupling parameter (P) and Fermi contact interaction parameter (k) have been evaluated. It is observed that the spin-Hamiltonian parameters do not vary much with the change in composition. It is observed that with increase of x, an increase occurs in tetragonal distortion for VO{sup 2+}. The number of spins (N) participating in resonance and the paramagnetic susceptibility ({chi}) have been calculated. It is observed that N and {chi} increase with x. The optical bandgap energies evaluated for these glasses slightly increase with x and reach a maximum around x = 20 and thereafter decrease showing the mixed alkali effect. Optical band gap energies obtained in the present work vary from 2.73 to 3.10 eV for both the direct and indirect transitions. The physical parameters of the glasses are also determined with respect to the composition.
- OSTI ID:
- 20889788
- Journal Information:
- Materials Research Bulletin, Vol. 40, Issue 6; Other Information: DOI: 10.1016/j.materresbull.2005.02.023; PII: S0025-5408(05)00071-1; Copyright (c) 2005 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved; Country of input: International Atomic Energy Agency (IAEA); ISSN 0025-5408
- Country of Publication:
- United States
- Language:
- English
Similar Records
Mixed alkali effect in Li{sub 2}O-Na{sub 2}O-B{sub 2}O{sub 3} glasses containing Fe{sub 2}O{sub 3}-An EPR and optical absorption study
EPR Study of Vanadium Ion in Zinc-Boro-Vanadate Glasses