Structural, optical and dielectric properties of Cr doped CoWO4 nanomaterial

Abstract

The present paper reports optical and electrical properties of undoped and Cr³⁺ doped CoWO₄ nanomaterials. The samples were successfully prepared at room temperature (RT) by simple co-precipitation method and at heat treated at 600 °C for good crystallization. The samples were carefully characterized by X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM). The room temperature optical properties were analyzed by UV–visible diffuse reflectance spectroscopy and photoluminescence (PL) spectroscopy. The XRD pattern reveals that the Cr³⁺ doped CoWO₄ samples shows single phase formation with wolframite monoclinic structure. SEM micrograph reveals that agglomerated round shaped particle in surface of the samples. The energy band gap value of the CoWO₄ nanomaterials decreased with increasing the Cr³⁺ concentration. The intrinsic emission of CoWO₄ nanomaterials were observed with excitation of 210 nm. The Cr³⁺ incorporation in CoWO₄ lattice have not altered the structure of emission spectra other than slight increase in emission intensity. The variation of dielectric constant with frequency and temperature has been studied. Moreover, the dielectric constant of the doped samples was higher than that of the CoWO₄ ceramics. The ac conductivity studies has been studied and Jonscher's power law has been used to calculate the DC conductivity and frequency exponential factor (n) for all the samples.