Role of Crystal Field in Mixed Alkali Metal Effect: Electron Paramagnetic Resonance Study of Mixed Alkali Metal Oxyfluoro Vanadate Glasses

Honnavar, Gajanan V and Ramesh, KP and Bhat, SV (2014) Role of Crystal Field in Mixed Alkali Metal Effect: Electron Paramagnetic Resonance Study of Mixed Alkali Metal Oxyfluoro Vanadate Glasses. In: JOURNAL OF PHYSICAL CHEMISTRY A, 118 (3). pp. 573-578.

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Abstract

The mixed alkali metal effect is a long-standing problem in glasses. Electron paramagnetic resonance (EPR) is used by several researchers to study the mixed alkali metal effect, but a detailed analysis of the nearest neighbor environment of the glass former using spin-Hamiltonian parameters was elusive. In this study we have prepared a series of vanadate glasses having general formula (mol %) 40 V2O5-30BaF(2)-(30 - x)LiF-xRbF with x = 5, 10, 15, 20, 25, and 30. Spin-Hamiltonian parameters of V4+ ions were extracted by simulating and fitting to the experimental spectra using EasySpin. From the analysis of these parameters it is observed that the replacement of lithium ions by rubidium ions follows a ``preferential substitution model''. Using this proposed model, we were able to account for the observed variation in the ratio of the g parameter, which goes through a maximum. This reflects an asymmetric to symmetric changeover of. the alkali metal ion environment around the vanadium site. Further, this model also accounts for the variation in oxidation state of vanadium ion, which was confirmed from the variation in signal intensity of EPR spectra.

Item Type:	Journal Article
Publication:	JOURNAL OF PHYSICAL CHEMISTRY A
Publisher:	AMER CHEMICAL SOC
Additional Information:	Copyright for this article belongs to the AMER CHEMICAL SOC, USA
Department/Centre:	Division of Physical & Mathematical Sciences > Physics
Date Deposited:	25 Feb 2014 08:34
Last Modified:	25 Feb 2014 08:34
URI:	http://eprints.iisc.ac.in/id/eprint/48462

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