Directional solidification of PMN0.65PT0.35 ferroelectric crystals at 1 and 7Â atm

Single crystals of 0.65Pb(Mg1/3Nb2/3)O3-0.35PbTiO3 were directionally solidified from the melt exposed to 7 atm air pressure (7 atm). The X-ray studies show that the obtained crystals have rhombohedral or tetragonal structure depending on the composition. In contrast to the experiments conducted at atmospheric pressure, the experiments conducted under 7 atm of air yielded transparent light-yellow crystals, free of pyrochlore phase. The temperature and frequency dependence of the dielectric constant and dielectric loss demonstrate a relaxor ferroelectric behavior. The room temperature dielectric constant ε measured on unpoled (0 0 1) oriented specimens is 8200, demonstrating high crystalline perfection.