Present and future of piezoelectric single crystals and the importance of B-site cations for high piezoelectric response.

High quality piezoelectric single crystals, such as Pb(Zn(1/3)Nb(2/3))O3-PbTiO3 (PZNT) and Pb(Mg(1/3)Nb(2/3))O3-PbTiO3 (PMNT), have been investigated, and, because their piezoelectric properties are greatly superior to those of Pb(Zr(1-x)Ti(x))O3 (PZT) ceramics, they have been used for certain transducer applications since the late 1990s. The present situation for these relaxor-PT (lead titanate) single crystals is summarized. In this review, some possible high Tc > 200 degrees C single crystals are also introduced. Single crystals of Pb(In(1/2)Nb(1/2))O3-PbTiO3 (PINT) binary system and Pb(Mg(1/3)Nb(2/3))O3-Pb(Sc(1/2)Nb(1/2))O3-PbTiO3 (PSMNT) tertiary system have been synthesized, and their electrical properties are reported. In addition, a novel guiding principle for discovering excellent piezoelectric materials, namely the presence of low molecular mass B-site ions that can enter the lead-perovskite Pb(B'B'')O3 structure, is introduced.