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)O-3 - xPbTiO(3) (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 d(33) (up to 3000 pC/N) and coupling factors k(33) and k(t) (up to 0.94 and 0.62 respectively), low mechanical factor of merit (Q(m) similar to 60), large dielectric constant epsilon(similar to 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 relaxer feature: for x=0.33 and 0.35. epsilon similar to T curves look sharp enough to show a normal ferroelectric like feature, however when T > T-m the epsilon similar to 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 epsilon and k(31).