Studies on physicochemical properties of pure and iron substituted chromium niobates, Cr1−xFexNbO4 (x=0, 0.2, 0.4, 0.6)

• Published in: Materials science & engineering. B, Solid-state materials for advanced technology Solid-state materials for advanced technology, 2017-03, Vol.217, p.63-73
• Main Authors: Sree Rama Murthy, A., Gnanasekar, K.I., Govindaraj, R., Jayaraman, V., Umarji, A.M.
• Format: Article
• Language: English
• Subjects: Bohr magneton; Chemical analysis; Chromium compounds; Chromium niobate; Conductivity; Current voltage characteristics; Electrical resistivity; Impedance; Impedance spectroscopy; Iron; Magnetic permeability; Microstructure; Mössbauer spectroscopy; Niobates; X ray analysis; X-ray photoelectron spectroscopy
• ISSN: 0921-5107; 1873-4944
• DOI: 10.1016/j.mseb.2016.12.001

[Display omitted] •Systematic increase in unit cell volume on iron substitution.•Similar mechanism of electronic conduction in these compositions.•Decrease in quadrupole splitting with increasing iron content in Mössbauer spectra.•Iron and chromium exhibited multiple valences, as identified from X-ray photoelectron spectra. Pristine and iron substituted chromium niobates (Cr1−xFexNbO4 with x=0, 0.2, 0.4 and 0.6) are prepared by solid-state synthesis and phase characterised by X-ray diffraction. Microstructure is determined using scanning electron microscope and micro-chemical analysis is performed by energy dispersive X-ray analysis (EDX). The current-voltage characteristics are studied in the temperature range of 423–723K. The electrical conductivity of sintered pellets is measured by impedance spectroscopy. Temperature dependent magnetization studies are performed using vibrating sample magnetometer (VSM) and room temperature Bohr magneton number is calculated from the magnetic susceptibility data. The conductivity is passed through a minimum at x=0.2 in Cr1−xFexNbO4 for x=0–0.6. X-ray photoelectron spectroscopic studies revealed the surface non-stoichiometry in these compositions.