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.

Keywords:

• Lead-free piezoelectric
• Polymorphic phase boundary
• BaTiO3
• BaZrO3
• CaTiO3

Additional information

Funding

This work was supported by King Mongkut's Institute of Technology Ladkrabang (Grant No KREF145904) and the work of N. Vittayakorn was funded by KMITL Grant No. 2562-01-05-46.