Synthesis, low temperature sintering and property enhancement of PMN-PT ceramics based on the dilatometric studies

A novel solid-state, single-step calcination route is adopted to synthesize pure perovskite phase of PMN1−x-PTx (x = 0.0, 0.2 and 0.35) ceramics by utilizing the information obtained from dilatometry in association with thermal analysis and XRD studies. Using nitrate- and carbonate-based starting materials fine particles of reaction intermediates (Pb3Nb2O8 type pyrochlores) are obtained in the temperature range of 600-700 °C. Higher calcination temperatures lead to the formation of B-site rich pyrochlores (Pb3Nb4O13 type pyrochlores), which is found to be detrimental for perovskite formation. The pyrochlore phase formed in-between 600 and 700 °C helps in achieving pure perovskite phase below 850 °C and bring down the sintering temperature to ∼1000 °C. In this method the material is exposed to >900 °C, only once during the entire processing, which is found to be beneficial in achieving better lead stoichiometry and the enhancement of the electronic properties. Ceramics of up to 93% theoretical density are investigated for their microstructure, dielectric and piezoelectric properties.