Microstructural effects on effective piezoelectric responses of textured PMN-PT ceramics

The effective piezoelectric properties of [001]_c fiber textured Pb(Mg_1/3Nb_2/3)O₃-PbTiO₃ (PMN-PT) ceramics were studied by phase-field modeling. The effects of microstructures such as texture, grain shape, grain boundaries, residual pores and heterogeneous growth templates were investigated. It was found that the degree of texture plays a dominant role in determining the properties. The pores, heterogeneous templates and grain boundaries reduce the properties significantly at high degrees of texture with the effect diminishing at decreasing degrees of texture. The presence of heterogeneous templates leads to a more significant reduction in the properties than pores although the piezoelectric coefficients of pores are zero. The shape of grains has a weak effect at all degrees of texture. By utilizing the experimentally measured microstructural parameters in the calculations and comparing the computed properties with the corresponding measurements, we showed that the low performance of sintered textured PMN-PT ceramics (d₃₃∼1000 pC/N) relative to single crystals (d₃₃∼2800 pC/N) is mainly due to the insufficiently high degree of texture even with Lotgering factors up to 0.9, while the influences of other microstructures are weak.