Structure and Grain Growth Habit of Directional Solidification Ceramics of (1-x)Pb(Mg_(1/3)Nb_(2/3))O_3 - xPbTiO_3 (x=0.30, 0.33, 0.38) Relaxor Ferroelectric Solid Solutions

This work describes the grain growth habit of the (1-x)Pb(Mg_(1/3)Nb_(2/3)) O_(3-x)PbTiO_3 (PMN-PT or PMNT) system ferroelectric solid solutions prepared by a directional solidification technique. The results show that the preferential direction of the grain growth depends not only on the composition of the melts, but also on the crucible pulling-down speed. For a fixed PMN/PT ratio, e.g. 62/38, higher speed of crucible pulling-down leads to a preferential grain growth ori- entation of [110], rather than the [111], which is usually reported in single crystal growth studies, whereas lower crucible pulling-down speed tends to produce [111] grain-orientation ceramics. When the crucible is pulled down at a certain rate, the preferential grain-growth orientation changes from [111] to [110] with reducing PbTiO_3 molar contents.