Structural, optical and dielectric properties of Bi substituted polycrystalline praseodymium chromate

Abstract

Polycrystalline powder samples of Pr1-xBixCrO3 (x = 0, 0.1, 0.2, 0.3) have been synthesized using solid state synthesis method. Structural study is performed using powder X-ray diffraction and Rietveld refinement. All the synthesized compounds are crystallized in an orthorhombic structure. Dielectric properties are studied in the frequency range from 100 Hz to 15 MHz at room temperature. It is observed that Bi substitutions in PrCrO3 at Pr site reduces the dielectric permittivity (ε′) and increases dielectric loss(tanδ) in low frequency region whereas in high frequency region, Bi substitution improves dielectric properties by reducing the dielectric loss (tanδ) and increasing the dielectric permittivity(ε′). The effect of local field (due to substitution of Bi+3 for Pr+3) on optical properties of PrCrO3 is studied using Diffuse Reflectance Spectroscopy. Optical study suggests that optical transitions in PrCrO3 are mainly due to Cr+3 ions in CrO6 octahedra with ground state 4F (t32g e0g). It is also observed that Bi doping strongly affects the optical properties of PrCrO3 and dramatically reduces the optical energy band gap from 3.19 eV for PrCrO3 to 2.14 eV for 20% Bi doping in PrCrO3. © 2021 Elsevier B.V.