Pyroelectric performance, dielectric response and conductive mechanism of BCHT lead-free piezoelectric ceramics via powder injection molding

Abstract

Lead zirconate titanate (PZT) ceramics exhibit excellent piezoelectric performance, which expands piezoelectric applications scope. However, the usage of toxic PbO causes serious harm to humans and ecological environment. Lead-free environment friendly (Ba0.85Ca0.15)(Hf0.10Ti0.90)O3 (BCHT) ceramics exhibit enhanced electrical properties when prepared via the powder injection molding process, relating to the polymorphic ferroelectric phases coexistence. Excellent pyroelectric properties are obtained in the BCHT ceramics, where pyroelectric anomaly and peak appear around 45 °C and 95 °C in temperature dependent pyroelectric coefficient and figures of merit, respectively, which can be attributed to the polymorphic phase transition and ferroelectric phase transition. Abnormal drastic change and large peak values of pyroelectric properties around the Curie temperature TC make the BCHT ceramics promising application for critical temperature detection. The dielectric response contribution was analyzed by Rayleigh formula fitting, where the reversible contribution takes major role at low temperatures and the irreversible contribution takes main effect at high temperatures. The conduction activation energy is 0.71 eV for the BCHT ceramics, which correlates with the increased oxygen vacancies induced by cations evaporation during sintering.

Keywords

• BCHT lead-free piezoelectric ceramics
• Pyroelectric properties
• Dielectric response contribution
• Conduction mechanism