High piezoelectric activity in lead-free BaTiO3-BaZrO3-CaTiO3 ceramics with near polymorphic phase boundary

Abstract

Lead-free 0.88BaTiO₃–(0.12-x)BaZrO₃–xCaTiO₃ (BT-BZ-xCT) ceramics were fabricated via solid state reaction. The effect of CaTiO₃ content on crystal structure, phase transition, and electrical properties was investigated systematically. The crystal structure and phase transition of ceramics were characterized by X-ray diffraction (XRD), Raman spectra and dielectric measurement. Results show that ceramic in the composition, x?=?0.02, exhibits a rhombohedral structure. Ceramics with increasing CT content transformed from a rhombohedral to orthorhombic structure in the composition, x?=?0.04, and eventually became a tetragonal structure at the composition, x?≥?0.08. The polymorphic phase boundary (PPB) was observed at the composition, x?=?0.06, with coexistence of orthorhombic and tetragonal phases showing at almost room temperature. This PPB composition exhibited a high piezoelectric response (d₃₃*) of 1,150?pm/V at 10?kV/cm as an electric field was applied. These results indicate that the materials studied have potential as candidates for lead-free piezoelectric ceramics.