Dielectric and Optical Properties of δ‐Bi₂O₃ Quaternary Semiconducting Solid Solutions

Abstract

Quaternary compositions of polycrystalline Bi1.74Dy0.14W0.12−xScxO3 (x = 0.02, 0.03, 0.04, 0.05, 0.06) solid solutions are synthesized by the solid‐state reaction method. The 4a site symmetry of the space group occupied by Sc3+ ion retains the cubic fluorite‐type over a wide temperature range (450–700 °C) for low Sc3+ content without losing the δ‐phase. Dielectric and ionic conductivity by complex impedance in the frequency range from 0.1 to 100 kHz suggests a temperature‐ and Sc3+‐dependent relaxation process. The ionic conductivity increases with the Sc3+ content over the whole tested temperature range. An oxygen ion conductivity of 0.102 Scm−1 at 700 °C and an activation energy of 0.32 eV are achieved for x = 0.06. Optical properties and Rietveld refinement indicate a bandgap reduction due to a bond length reduction (Bi—O). These materials have potential in photocatalysis and water‐splitting technology due to their UV and visible region absorption capabilities.