Correlations between EPR and optical properties: Diborovanadate glasses in a highly modified regime

Harikamalasree, Harikamalasree and Chethana, BK and Viswanatha, R and Reddy, Sivasankara N and Reddy, Narayana C (2017) Correlations between EPR and optical properties: Diborovanadate glasses in a highly modified regime. In: JOURNAL OF NON-CRYSTALLINE SOLIDS, 477 . pp. 12-20.

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Abstract

Glasses with composition x V2O5 - 10PbO- (90- x) NaBO2 with 10 <= x <= 30 were prepared by a novel, energy-efficient and economical microwave method. The Electron Paramagnetic Resonance (EPR) spectra of all the glasses investigated exhibited a well-defined hyperfine structure, from which the spin Hamiltonian parameters of the VO2+ ion, dipolar hyperfine coupling parameters, and the fermi-contact interaction term (K) have been calculated. The values of g-tensor reveal the existence of the VO2+ ion in octahedral coordination with a tetragonally compressed site. The variations seen in P, K, P beta K-2 and PK/gamma with V2O5 content indicate the s character of the magnetic spin of vanadium which arises due to the partial unpairing of s-electrons. Also, a decrease in K with V2O5 mol% suggests a strong V=O interaction, makes the bond length (V-O) in the vanadyl group shorter and distorts the vanadyl group from O-h to C-4v. The EPR and UV-Vis parameters are analyzed on the basis of structural motifs formed due to the network modification. The molecular orbital coefficients a2 and gamma(2) have been calculated. The ratio, (1-gamma(2)/1-alpha(2)) increases with increasing V2O5 mol%, suggesting that the a-bonding between the V atom and the equatorial ligand is weakening. IR studies reveal the presence of BO3/2](0), BO4/2](-) and B2V2O9](2-) structural groups in the glass matrix.

Item Type:	Journal Article
Publication:	JOURNAL OF NON-CRYSTALLINE SOLIDS
Additional Information:	Copy right for this article belongs to the ELSEVIER SCIENCE BV, PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS
Department/Centre:	Division of Chemical Sciences > Solid State & Structural Chemistry Unit
Date Deposited:	17 Nov 2017 06:28
Last Modified:	01 Mar 2019 07:18
URI:	http://eprints.iisc.ac.in/id/eprint/58246

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