Abstract: Relaxor ferroelectric single crystals Pb(Mg_1/3Nb_2/3)O₃-38%PbTiO₃ were grown directly from melt by a
modified Bridgman technique. The segregation during the process of crystal growth was studied in details by measuring the Curie temperature and XRFA. The
results show that the PbTiO₃ content increases with the distance from the seed crystal. Through measuring the Curie temperature of the samples
taken from the bottom and top of PMNT62/38 single crystal it is found that there exists variation of PT content along the parallel and perpendicular
to the growth direction respectively. Due to the segregation, the PT content in the bottom is 35.2mol% and in the top, 43mol% and the dielectric and
piezoelectric properties are different from each other. For the bottom samples the piezoelectric module for (110) is 1200pC/N, for (111) 789pC/N
and for (001) 371pC/N. The dielectric constants (poled) in (110) and (111) orientations are larger than that of (001) and tend to increase with the
temperature decreasing.

Key words: PMN-PT single crystal, segregation, cut orientation, dielectric and piezoelectric properties