The effect of MgO addition on grain growth in PMN-35PT

Abstract

When Pb(Mg1/2Nb2/3)O-3-35PbTiO(3) (mol%) (PMN-35PT) is sintered at 1200 degrees C after packing in PbZrO3 powder, the grains show normal growth with time invariant normalized grain size distributions. If 0.5 wt% MgO is added to PMN-35PT, abnormal grain growth occurs with the large abnormal grains developing nearly cubic shapes. The interfaces between grains and PbO-rich liquid at grain triple junctions are flat, indicating that they are singular. Many central segments of the liquid films and possibly grain boundaries between the abnormal grains and the small neighboring grains are also flat along the {100} planes of the abnormal grains. The abnormal grain growth in the MgO-doped specimens is likely to be caused by the presence of these singular interfaces. Most of the large abnormal grains do not contain any Sigma = 3 penetration twin boundaries unlike the previous observations in PbO-excess PMN-35PT.