Dielectric and Piezoelectric Properties of Ceramics

Dielectric and piezoelectric properties of (Na0.8K0.5)0.5Bi0.5TiO3 ceramics were investigated. The results show that ferroelectric-antiferroelectric and antiferroelectric-paraelectric phase transition with relaxor characteristic occur from room temperature to 500℃, leading to the two peaks of electric permittivity to temperature. At room temperature, it has relative high rema-nent polarization Pr=29.4/μC/cm2 and low conceive field Ec=2.8kV/mm. The polarized ceramics have good piezoelectric properties such as piezoelectric constant d33=120pC/N, electromechanical coupling factor Kp=28.5%, frequency constant Nφ=2916Hz·m, as well as minimum resonance frequency temperature coefficient at 120℃.