Low-temperature fabrication and crystallization behavior of Pb(Mg_1/3Nb_2/3O₃) crystallites by a hydrothermal process

Perovskite Pb(Mg_1/3Nb_2/3)O₃ (PMN) crystallites were synthesized via a single-step process, namely a hydrothermal process, at low temperature, by using PbO, MgO and Nb₂O₅ as precursors. PMN were obtained when the precursors were heated to 150 °C for 24 h with KOH concentration of 11 M. Effects of the initial KOH concentration, temperature and reaction time on the phase evolution and morphologies of PMN crystallites were systematically investigated. The optimum KOH concentration was found to be 11 M, which led to the stabilization of the perovskite powder against the pyrochlore phase, and to the growth of high-quality PMN crystallites suitable for subsequent characterization. According to morphological evolution during the reaction, a possible growth mechanism was proposed based on the dissolution-crystallization process.