Synthesis, phase segregation and properties of piezo-/ferroelectric (1−x)Pb(Sc1/2Nb1/2)O3–xPbTiO3 single crystals

Single crystals of the (1−x)Pb(Sc1/2Nb1/2)O3–xPbTiO3 [PSN–PT] solid solution are synthesized by the high-temperature solution method using PbO flux with B2O3 additive. The grown PSN–PT single crystals contain a Ti concentration lower than the nominal composition (x=0.425-0.51x=0.425-0.51). The effective phase segregation coefficient is found to be k=0.73k=0.73 for the solid solution. Based on the segregation trend, the PSN–PT crystals of compositions within the morphotropic phase boundary (MPB) region are successfully grown. The MPB crystals show good dielectric and ferroelectric properties with a maximum dielectric constant of 60,000 (at 1 kHz) at TC=213°C and a remnant polarization of 25 μC/cm2 at room temperature. The electromechanical coupling factor k33 of the pre-poled crystals reaches 78%. The TC and TMPB of the PSN–PT crystals are much higher than those of the Pb(Mg1/3Nb2/3)O3 (PMN)–PT and Pb(Zn1/3Nb2/3)O3 (PZN)–PT piezocrystals, making them very interesting high-TC and high-performance piezoelectric materials.