Structure and properties of hot-pressed lead-free (Ba0.85Ca0.15)(Zr0.1Ti0.9)O3 piezoelectric ceramics

Abstract

Randomly-oriented and textured (Ba_0.85Ca_0.15)(Zr_0.1Ti_0.9)O₃ (BCZT) ceramics are prepared by a hot-pressing (HP) method. The phase structure, microstructure, and electrical properties are systematically investigated. Structural analysis shows a decrease in tetragonality of the hot-pressed samples. The orientation of the as-processed ceramics is studied by X-ray diffraction and electron backscatter diffraction, revealing an increase in texture of the hot-pressed textured BCZT ceramics. Microstructure characterization demonstrates that the hot-pressing can greatly improve the densification of the BCZT ceramics. Dielectric constant measurement obeys a modified Curie–Weiss law. The relaxor-like behavior is decreased in hot-pressed samples. The Curie temperatures of the hot-pressed BCZT (BCZT-HP) and the hot-pressed BCZT with texture templates (BCZT-T-HP) ceramics are greatly increased to 76 °C and 90 °C, respectively. The optimum piezoelectric properties for the BCZT-HP and BCZT-T-HP ceramics are d₃₃ = 510 pC N⁻¹, k_p = 44%, d₃₁ = −182 pC N⁻¹, k₃₁ = 23% and d₃₃ = 580 pC N⁻¹, k_p = 49%, d₃₁ = −204 pC N⁻¹, k₃₁ = 31%, respectively. Therefore, the BCZT-HP and BCZT-T-HP ceramics are promising lead-free piezoelectric ceramics which can be used in higher temperature than their counterparts prepared by conventional sintering.