Physical, structural, and magnetic study of dilute magnetic glasses: xFe2O3 + (2 − x)V2O5 + 38Li2O+60P2O5

Abstract

Dilute magnetic glasses of formula xFe2O3 + (2 − x)V2O5 + 38Li2O + 60P2O5 (where x = 0, 0.2, 0.5, 0.7, 1.0, 1.5 and 2.0) are synthesized by melt quench technique. The glassy nature is confirmed by X-ray diffraction. The density is found to increase but the molar volume and optical basicity are found to decrease as the iron content x is gradually increased from 0 to up to 2. The Fourier transform infrared spectra of these glasses show absorption peaks corresponding to P=O, O-P–O–, (P–O–P) symmetric stretching, (P–O–P) asymmetric stretching, and O–P–O group bending vibrations. The magnetic measurements indicate considerable reduction in magnetization of both vanadium and iron containing glasses. A canted-antiferromagnetic pairing of the magnetic ion pairs is envisaged for explaining the reduction of magnetization. The EPR spectra reveal the presence of vanadyl ion and ferric ion in the glasses. Characteristics of local bonding and co-ordination of vanadyl and ferric ions are discussed. The vanadyl ion is shown to have a distorted octahedral coordination with oxygen to create a tetragonal contraction. The high spin ferric ion is concluded to possess two kinds of co-ordinations with oxygen viz. rhombic and octahedral in these glasses. The effects of magnetic exchange on the EPR features are discussed.