IMF2017

Relaxor based ferroelectric single crystals Pb(In_1/2Nb_1/2)O₃-Pb(Mg_1/3Nb_2/3)O₃-PbTiO₃(PIN-PMN-PT) with composition near morphotropic phase boundary exhibit extraordinary piezoelectric properties. In order to make large crystal growth more efficient, the characteristics of heat and mass transport in the growth process of PIN-PMN-PT single crystal were also simulated by changing macro parameters, such as furnace structure, temperature distribution, and interface shape. It is found that the suitable conditions would reduce the save time and improve crystal quality. Large bulk single crystal with 108 mm in diameter and 170 mm in length was successfully grown by modified Bridgman method. Dielectric, piezoelectric and ferroelectric properties of the [001] samples along single crystal growth direction were systematically measured. The excellent properties (d₃₃ - 2700 pC/N, k₃₃ - 0.94, d₁₅ - 4500 pC/N, k₁₅ - 0.91, E_C - 4 kV/cm, T_C - 180 °C, T_RT - 100 °C) were found near morphotropic phase boundary. However, due to composition segregation, morphotropic phase boundary is narrow region in the as-grown crystal boule. It is found that the uniform composition with relatively high properties was appeared in the rhombohedral phase near MPB which take up 70% length of crystal boule. In this region, piezoelectric constant d₃₃, T_RT and Curie temperature are about 1500-1800 pC/N, 110 °C and 160-180 °C, respectively. In the same range of boule, PIN, PMN and PT content was around 24 mol%, 44 mol% and 32 mol%.