Role of the addition of Pb(Li 1/4 Fe 1/4 W 1/2 )O 3 in the low-temperature sintering and dielectric characteristics of Pb(Mg 1/3 Nb 2/3 )O 3 ceramics

The sintering behavior and dielectric characteristics of Pb (Li 1/4 Fe 1/4 W 1/2 )O 3 -added Pb (Mg 1/3 Nb 2/3 )O 3 ceramics were investigated. Mixing the two end-members for 4h only formed a mixture, however, 48h-mixing mechanochemically induced the reactants to form partial perovskite solid-solutions. In the mixture specimen, the melt of Pb (Li 1/4 Fe 1/4 W 1/2 )O 3 acted as a reactive liquid phase to substantially enhance the densification of Pb (Mg 1/3 Nb 2/3 )O 3 , and caused grains to grow greatly and resulted in nonuniform microstructure. Regardless of mixing conditions, pure perovskite solid-solutions were formulated at 1000¢XC when the content of Pb(Li 1/4 Fe 1/4 W 1/2 )O 3 was less than 10 mass%, whereas, adding excess Pb(Li 1/4 Fe 1/4 W 1/2 )O 3 unfavorably caused polyhedral pyrochlore phase to form in the matrix. The addition of Pb(Li 1/4 Fe 1/4 W 1/2 )O 3 decreased the broad maximum of dielectric permittivity of sintered specimens; nevertheless, this addition markedly suppressed the temperature dependence of dielectric permittivity. The ceramics fabricated by the mixture of two end-members possessed a larger apparent diffusiveness of dielectric permittivity than those prepared from the partial solid-solution, implying that a wider compositional fluctuation likely occurred in the former specimen.