Phase developments in Pb(Mg1/2W1/2)O3 and Pb(Zn1/2W1/2)O3 via B-site precursor route

Phase formation stages of MgWO4 and ZnWO4 (precursor compositions for following steps) were investigated by monitoring the reactions of oxide chemicals at various temperatures. Developed phases were examined by using X-ray diffraction (XRD). Successive attempts were also conducted for Pb(Mg1/2W1/2)O3 (PMW) and Pb(Zn1/2 W1/2)O3 (PZW) by reacting PbO with the precursor compounds. Stages of phase development in the two compositions were also analyzed. The results are compared with those of another tungsten-containing perovskite Pb(Fe2/3W1/3)O3 (PFW) and its B-site precursor Fe2WO6. After PbO addition to the precursor powders, a perovskite phase formed directly (i.e., without any intermediate phases) in the case of PMW. For PbO + ½ZnWO4, in contrast, the decomposition of ZnWO4 and preferential reaction with PbO resulted in Pb2WO5 and ZnO, instead of the perovskite PZW.