Phase structure and electrical properties of (1-x)Bi1+yFeO3-xBaTiO3 lead-free ceramics with different Bi contents

Abstract

In this work, (1-x)Bi1+yFeO3-xBaTiO3 (x = 0.25, 0.30, 0.35, 0.40; y = − 0.02, 0.00, 0.02, 0.04) ceramics were prepared via the solid-state reaction method. The effects of BaTiO3 doping and different Bi contents on the phase structure, microstructure, and electrical properties of the ceramics was investigated. Compared with pure BiFeO3, doping with BaTiO3 can significantly improve the electrical properties of the ceramics through affecting the phase structure. It is found that the phase structure undergoes a transition from a rhombohedral to a pseudo-cubic phase as x increases. The ceramics with x = 0.30 can be considered as a morphotropic phase boundary, where the rhombohedral and pseudo-cubic phases coexist; furthermore, their electrical performance was improved (Pr = 23.9 µC/cm2, EC = 28.5 kV/cm, $${d}_{33}^{*}$$ = 237 pm/V, TC = 419 °C). Bi excess can improve the dielectric performance of the ceramics at high temperature; however, a severe deficiency of Bi can induce a change in the structure from a mixed phase to a rhombohedral phase where an impurity phase is produced, thus reducing the ceramics performance.