Enhanced Ferroelectric and Piezoelectric Properties of (1-)PMN-PT Ceramics Based on a Partial Oxalate Process.

The pyrochlore phase in ferroelectric and piezoelectric materials is the main obstacle device application due to its poor electrical properties. Especially, the pyrochlore phase is frequently observed in the perovskite-based metal-oxide materials including piezoelectric and ferroelectric ceramics, which are based on solid-state reaction methods for fabrication. To overcome these problems, advanced innovative methods such as partial oxalate process will be investigated. In this method, crystalized magnesium niobite (MN) and lead titanate (PT) powders will be coated with a certain amount of lead oxalate and, then, the calcination process can be carried out to form the PMN-PT without pyrochlore phase. In this study, (1-)PMN-PT ceramics near the morphotropic phase boundary (MPB), with compositions of = 0.25⁻0.40, have been prepared employing the partial oxalate method at various temperatures. The crystalline, microstructure, and piezoelectric properties of (1-)PMN-PT ceramics depending on the sintering temperature were intensively investigated and discussed. By optimizing the sintering temperature and compositions from the PMN-PT ceramics, the maximum value of the piezoelectric charge coefficient () of 665pC/N, planar electromechanical coupling factor () of 77.8%, dielectric constant () of 3230, and remanent polarization () of 31.67 μC/cm² were obtained.