Structural and piezoelectric properties of high-density (Bi0.5K0.5)TiO3–BiFeO3 ceramics

The crystal structures and dielectric, polarization, and piezoelectric properties of high-density x(Bi0.5K0.5)TiO3–(1−x)BiFeO3 ceramics were investigated. The results obtained using x-ray and neutron powder diffractions and transmission electron microscopy showed that a morphotropic phase boundary between the rhombohedral (ferroelectric) and pseudocubic (ferroelectric) phases is present in 0.4<x<0.43. Ceramics with x=0.4 exhibited a large remanent polarization of 52 μC/cm2 at 25 °C and their piezoelectric properties were maintained up to 300 °C. It is suggested that the presence of nanosized domains with a polar rhombohedral structure observed for x=0.4 is the origin of relaxor-like dielectric properties.