Textured ferroelectric ceramics with high electromechanical coupling factors over a broad temperature range

Abstract

The figure-of-merits of ferroelectrics for transducer applications are their electromechanical coupling factor and the operable temperature range. Relaxor-PbTiO₃ ferroelectric crystals show a much improved electromechanical coupling factor k₃₃ (88~93%) compared to their ceramic counterparts (65~78%) by taking advantage of the strong anisotropy of crystals. However, only a few relaxor-PbTiO₃ systems, for example Pb(In_1/2Nb_1/2)O₃-Pb(Mg_1/3Nb_2/3)O₃-PbTiO₃, can be grown into single crystals, whose operable temperature range is limited by their rhombohedral-tetragonal phase transition temperatures (T_rt: 60~120 °C). Here, we develop a templated grain-growth approach to fabricate -textured Pb(In_1/2Nb_1/2)O₃-Pb(Sc_1/2Nb_1/2)O₃-PbTiO₃ (PIN-PSN-PT) ceramics that contain a large amount of the refractory component Sc₂O₃, which has the ability to increase the T_rt of the system. The high k₃₃ of 85~89% and the greatly increased T_rt of 160~200 °C are simultaneously achieved in the textured PIN-PSN-PT ceramics. The above merits will make textured PIN-PSN-PT ceramics an alternative to single crystals, benefiting the development of numerous advanced piezoelectric devices.