Abstract: Dielectric and piezoelectric properties of (Na_0.8K_0.2)_0.5Bi_0.5TiO₃ 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 remanent polarization P_r=29.4μC/cm² and low conceive field E_c=2.8kV/mm. The polarized ceramics have good piezoelectric
properties such as piezoelectric constant d₃₃=120pC/N, electromechanical coupling factor K_p=28.5%, frequency constant N_φ=2916Hz·m,
as well as minimum resonance frequency temperature coefficient at 120℃.

Key words: sodium-bismuth titanate, dielectric properties, piezoelectric properties, relaxor phase transition, antiferroelectric