A modified two-stage mixed oxide synthetic route to lead magnesium niobateand lead iron niobate

A modified mixed oxide synthetic route has been developed for the synthesis of lead magnesium niobate [Pb(Mg1/3Nb2/3)O-3; PMN] and lead iron niobate [ Pb(Fe1/2Nb1/2)O-3; PFN] powders. The formation of perovskite and pyrochlore phases in the calcined PMN and PFN powders has been investigated as a func tion of calcination temperature and time by XRD and DTA techniques. The par ticle size distribution of calcined powders was determined by laser diffrac tion, with the morphology, phase composition and crystal structure determin ed via SEM, TEM and EDX techniques. In both cases it has been found that cu bic pyrochlore phases in the PbO-Nb2O5 system tend to form, as well as the perovskite phase. However, pyrochlore-free PMN and PFN powders were success fully obtained for a calcination temperature of 800 degrees C for 4 and 3 h , respectively, without the introduction of excess PbO and/or MgO. (C) 1998 Elsevier Science Limited All rights reserved.