Structural, Physical, Electrical and Dielectric Properties of Magnetic Glasses: xFe₂O₃+(30-x)V₂O₅ + 30Na_2O + 40B₂O₃ with x=0 to 15

Abstract

Magnetic glasses compositions: xFe2O3 + (30 − x)V2O5 + 30Na2O + 40B2O3 (x = 0, 2, 3, 5, 7, 10, and 15), abbreviated as FVNBx, are prepared with conventional melt-quenching technique, and the structural, physical, and electrical properties of compositions are investigated. The amorphous nature of the FVNBx glasses is confirmed using X-ray diffraction technique. It is found that the density of the glasses increases with x. The molar volumes calculations are based on the molar mass and the density data, which are then correlated with the structural changes. The decrease in the theoretical optical basicity shows marginal increase in the covalence of oxygen, when the V2O5 content is replaced with Fe2O3. The Fourier transform infrared spectroscopy that is carried out in the mid-IR region, shows the absence of the six-atomic (B3O3) boroxol rings. In this paper, the IR absorption bands corresponding to the combined contributions of tri and tetra borate vibrations are identified. The distinct IR spectra of the samples with different x indicates that the iron acts as a strong glass modifier, and brings only noticeable microstructural changes in the glass structures. Fe2O3 is believed to act as both glass former and glass modifier. The increase of DC electrical conductivity with temperature indicates a semiconducting nature of the glasses. The replacement of V2O5 by Fe2O3, even by 1 mol%, decreases the DC conductivity by an order of magnitude, and increases the activation energy by a factor of two. Composition, frequency, and temperature dependence of different dielectric parameters, namely dielectric constant ε , dielectric loss ε , loss tangent tan(δ), electrical modulus M * , etc., are also analyzed.