Characters of piezoelectricity and phase transition of PMN-PT single crystal and ceramics

Some special features in dielectric properties, 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 crystal 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 Ε (-5000). 2) Strong orientation dependence of piezoelectric properties. 3) With increasing PT content, the system becomes less relaxational, but at least up to x=0.35, white the system still partly exhibits relaxor feature: for x=0.33 and 0.35, Ε-T curves look sharp enough to show a normal ferroelectric like feature, and when T>Tm the Ε-T relation does not obey Curie-Weiss law but follows Smolenskii's relation. The piezoelectric properties of PMN-PT ceramics are similar to that of PZT-5H, but with higher Ε and k31.