Morphology and defect structures of novel relaxor ferroelectric single crystals Pb(Mg1/3Nb2/3)O3-PbTiO3

High-performance relaxer ferroelectric single crystals Pb(Mg1/3Nb2/3)O-3-PbTiO3 have been grown successfully by a modified Bridgman method. They have the size of 25 x 25 x 50 mm(3) and are of pure perovskite phases with tetragonal or rhombohedral structures. Their {001} faces appear dominantly, which can be interpreted by the model of anionic coordination polyhedral growth units. Main macro defects observed under optical microscopes and SEM can be reduced or removed by improving growth parameters after understanding their formation mechanism. 71 degrees or 109 degrees macrodomains in rhombohedral PMNT 76/24 crystals and 90 degrees macrodomains in tetragonal PMNT 65/35 crystals have been observed by optical microscopes. It has been found that the transition from microdomains to macrodomains can be induced by compositions. Both the imaging mechanism of non-180 degrees domains and the relation between domain configurations and ferroelectric phase transition have been analyzed.