Fabrication of PMN-PT Single Crystals by Using the Exaggerated Grain Growth Method

摘要

Polycrystalline 65 mole% Pb(Mg1/3Nb1/3)O3 -35 mole% PbTiO3 (PMN-PT) specimens were prepared by conventional and spark-plasma sintering. Conventional sintering at 1200 deg C produced 92% dense specimens, whereas spark-plasma sintering at 900 deg C produced 99% dense specimens. Addition of slight excesses of Mg accelerated grain growth, but additions of Nb retarded grain growth. In addition, excess Mg decreased dielectric and piezoelectric properties. Grain- growth studies indicated that abnormal grain growth (AGG) occurred when excess Pb was present. The AGG was ascribed to formation of sum 3 coincidence-site- lattice and low-angle grain boundaries. Because of reentrant edges appearing at the ends of these boundaries, grain-coarsening rates were significantly enhanced. However, single crystals could not be made by an AGG process.