Exceptionally large piezoelectric strains in BiFeO3–(K0.5Bi0.5)TiO3–PbTiO3 ceramics

Samples of (1−x−y)BiFeO3–x(K0.5Bi0.5)TiO3–yPbTiO3, where x = 0.15 and y = 0.275, were produced via a conventional mixed oxide method. Ceramics were characterized using X-ray diffraction, confirming an electric-field-induced phase change from predominantly rhombohedral to mixed phase tetragonal and rhombohedral structure upon poling. There was a remnant polarization of 34 μC cm−2 and a total strain of 0.805% at 6.5 kV mm−1, the highest electric-field-induced strain reported in a polycrystalline material. A d33 of 205 pm V−1 was measured and Rayleigh analysis was used to quantify the extrinsic contributions.