Abnormal dielectric properties and phase transition in Bi0.783(Mo0.65V0.35)O4 scheelite-related structured ceramic

Abstract

In the present work, an interesting phase transition at 150 °C in ordered scheelite structured Bi_0.783(Mo_0.65V_0.35)O₄ ceramic was observed for the first time. This phase transition was believed to be related to the ordered arrangement of A site defects (or A site cations Bi³⁺). X-ray diffraction (XRD) and Raman spectra were employed to study the structure. Thermal expansion data showed that a sudden decrease in cell volume was observed during the phase transition, which resulted in a sharp increase in dielectric permittivity and loss over a wide frequency range (100 Hz to 7.5 GHz). Far-infrared reflectivity and THz spectra were used to study the intrinsic dielectric properties. It was found that the Bi–O stretches contributed mainly to the polarization. This study extended the design of A site ordered scheelite structured materials and the knowledge of their phase transitions.