Piezoelectric performance of the binary K1/2Bi1/2TiO3?LiTaO3 relaxor-ferroelectric ceramics

Abstract

The (1-x)K1/2Bi1/2TiO3 - xLiTaO3 lead-free perovskite solid solution, x ≤ 0.08, is shown to be a relaxor-ferroelectric with enhanced electromechanical properties for compositions x = 0.02–0.03. The X-ray powder diffraction data revealed: tetragonal for x = 0 and 0.01; mixed phases (tetragonal and cubic) at x = 0.02–0.03; and single phase cubic at x = 0.04. Mixed phase compositions, x = 0.02–0.03, gave a Berlincourt piezoelectric charge coefficient (d33) of 135 pC/N with electric field induced strains of up to 0.14% (at applied electric field 50 kV/cm). The maximum value of relative permittivity (ϵr) was ∼5200 for composition x = 0.20 at 1 kHz. The ferroelectric-polarization response for the mixed phase compositions showed evidence of ferroelectric switching, with coercive fields (Ec) is ∼20 kV/cm and remnant polarization (Pr) approximately 10 μC/cm2.