Synthesis of Pb(Mg1/3Nb2/3)O3 and Pb(In1/2Nb1/2)O3 ceramics by b-site precursor method

Pb(Mg1/3Nb2/3)O3 and Pb(In1/2Nb1/2)O3 ceramics were synthesized by b-site precursor method which is widely used for making Pb-related complex perovskite materials. The intermediate phases formed during the heating process were analyzed, and the mechanism of the perovskite formation was discussed. The cubic pyrochlore phase (Pb3Nb4O13) was formed at approximately 600 °C but had almost disappeared at temperature over 650 °C in the case of 3PbO–MgNb2O6 mixture. In contrast, it was formed around 600 °C without the formation of the perovskite phase and remained even at temperature as high as 900 °C in the case of the 2PbO–InNbO4 mixture. These differences were attributed to the shorter bond length and the small electronegativity difference in the InO bond in InNbO4 than those of the MgO bond in MgNb2O6, which means that InNbO4 has a relatively lower structural stability.