Lead-free electrostrictive bismuth perovskite ceramics with thermally stable field-induced strains

Abstract

Electric field-induced strain (EFIS) properties of Bi 1/2(Na 0.82K 0.18) 1/2TiO 3 (BNKT) ceramics modified with Sr(K 1/4Nb 3/4)O 3 (SKN) have been investigated as functions of composition and temperature. BNKT ceramics near a phase boundary revealed the coexistence of ferroelectric rhombohedral and tetragonal phases, resulting in a typical ferroelectric butterfly-shaped bipolar S– E loop at room temperature, whose normalized strain ( S max/ E max) showed a significant temperature coefficient of 0.38 pm/V/K. However, 5 mol% SKN-modified BNKT ceramics revealed a typical electrostrictive behaviour with a thermally stable electrostrictive coefficient, Q 33 = 0.021 m 4/C 2, which is almost comparable to that of Pb(Mg 1/3Nb 2/3)O 3 (PMN) ceramics that have been dominantly used as Pb-based electrostrictive materials over the last decades.