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-PT x (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 deg. 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 deg. C helps in achieving pure perovskite phase below 850 deg. C and bring down the sintering temperature to ∼1000 deg. C. In this method the material is exposed to >900 deg. 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