Fabrication, characterisation and formation mechanism of Pb_1.83Mg_0.29Nb_1.71O_6.39 Pyrochlore

摘要

Pb_1.83Mg_0.29Nb_1.71O_6.39 (PMN) pyrochlore ceramics were fabricated from solid state reaction of mixed oxides and by partial oxalate methods. For both methods the pyrochlore crystal structure as not formed directly but via a sequence of intermediate reactions. However, the formation temperature of PMN pyrochlore was lower for the partial oxalate Method due to the higher reactivity of these Powders. Microstructural investigation of pellets Produced from mixed oxides and partial oxalate Powders prepared using columbite (MgNb_2O_6) Revealed only single-phase pyrochlore whereas those Produced from partial oxalate powders made using Uncalcined Mg and Nb oxides contained clusters Of perovskite grains with intergranular Mg-rich Phases.