Coupled TG–MS study on the intermediate for formation of PbO(t) from PbO(O) in synthesis of perovskite PMN–PT

Pb(OH)2 was previously proposed as an intermediate in the synthesis of PMN [Pb(Mg1/3Nb2/3)O3] and PMN–PT [0.9Pb(Mg1/3Nb2/3)O3–0.1PbTiO3] from a mixture of PbO, Nb2O5, Mg(NO3)2·6H2O (w/w0) TiO2 by the modified mixed oxide method based on TG/DSC and XRD data. Coupled TG–MS of the precursor reveals that the intermediate is Pb6O5(NO3)2, not Pb(OH)2 because the evolved gas was nitric oxide and oxygen, not water.