XPS, DRUV-VIS and ESR characterization of the non-stoichiometric compound Ge$_{0.74}$V$_{0.21}$ $\square_{0.05}$O$_{2}$

Abstract

Microcrystalline powders of the nonstoichiometric Ge$_{0.74}$V$_{0.21}$ $\square_{0.05}$O$_{2}$ compound were prepared by conventional high temperature solid-state reactions. The powders were characterized by X-ray diffraction (XRD); scanning electron microscopy (SEM); X-ray photoelectron spectroscopy (XPS); diffuse reflectance ultraviolet-visible spectroscopy (DRUV-VIS) and electron spin resonance (ESR) spectroscopy. From the analysis performed on compound, it was found that: The powders showed a rutile type crystalline structure with a rectangular prismatic crystalline habit. The XPS analysis, confirm the presence of V$^{4+}$ and V$^{5+}$ vanadium ions, the DRUV-VIS spectra show absorption bands in the 200-800 nm wave length interval and the ESR analysis confirms that the V$^{4+}$ ions are within microcrystals, hosted as VO$^{2+}$ at sites of rhombic (C$_{2v}$) symmetry.