How synthesis parameters influence the quality of lead magnesioniobate PbMg1/3Nb2/3O3

Lead magnesioniobate PbMg 1/3 Nb 2/3 O 3 (PMN) has been prepared using lead oxide and magnesium niobate. Factors that influence the perovskite/pyrochlore ratio in the PMN structure have been studied. In order for the maximal amount of the perovskite phase to be obtained, synthesis should be carried out at 850–900°C; an excess of MgO (1–5 wt %) does not exert a positive effect. An excess of PbO (5–7 wt %) allows one to obtain a phase that contains 85% PMN, with the perovskite structure. The perovskite lattice is found to be stabilized as a result of cationic substitutions (Yb, Lu) in the Mg-Nb sublattice due to the formation of solid solution Pb(Mg 1/3 Nb 2/3 ) 1 − x Yb(Lu) x O 3 , where 0 ≤ x ≤ 0.9.