Reaction Mechanism of 0.80Pb(Mg1/3Nb2/3)O3 -0.20PbTiO3 Ceramics Prepared by Semichemical Method
半化学法制备0.80Pb(Mg1/3Nb2/3)O3-0.20PbTiO3陶瓷的反应机理

The semichemical method was developed for the synthesis of 0.80Pb(Mg1/3Nb2/3)O3-0.20PbTiO3(0.80PMN-0.20PT) ceramics with pure perovskite phase. The precursors were prepared by adding an aqueous Mg(NO3)2 solution rather than MgO to the alcoholic slurry of PbO, TiO2 and Nb2O5. The TG-DTG-DSC and XRD analysis show that the mechanism in this method is different from those of the known columbite or conventional mixed oxide method. Mg(NO3)2 reacts with PbO to form a intermediate of Pb6O5(NO3)2 at milling and calcinations process. The activated PbO and Pb3O4 by the intermediate reacted with Nb2O5 to form an unstable B-deficient pyrochlore structure of Pb3Nb2O8 , which progressively inserts magnesium oxide to transform into PMN-perovskite phase.