Characters of Piezoelectricity and Phase Transition of PMN-PT Single Crystals and Ceramics

Some special features in dielectric, piezoelectric properties and phase transition behavior of (1 - x)Pb(Mg1/3Nb2/3)O3 - xPbTiO3 (PMN-PT) (x=0.24, 0.3, 0.33 and 0.35) single crystals grown by Bridgman method were outlined: 1) Extremely high piezoelectric constant d33 (up to 3000 PC/N) and coupling factors k33 and kt (up to 0.94 and 0.62 respectively), low mechanical factor of merit (Qm~60), large dielectric constant (~5000).2) Strong orientation dependence of piezoelectric properties. 3) with increasing PT content, the system becomes less relaxational, but at least upto x=0.35, the system still partly exhibites relaxor feature: for x=0.33 and 0.35. ~ T curves look sharp enough to show a normal ferroelectric like feature, however when T Tm the ~ T relation does not obey Curie-Weiss law, but follows Smolenskii's relation. The piezoelectric properties of PMN-PT ceramics are similar to PZT-5H, but with higher e and k31.