Low temperature synthesis of the microwave dielectric Bi2O3–MgO–Nb2O5 nano powders by metal-citrate method

The microwave dielectric (Bi1.5Mg0.5)(Mg0.5Nb1.5)O7 (BMN) nano powders were synthesized by metal-citrate process and their sintering behaviors were evaluated. The single phase of cubic pyrochlore was achieved at a low temperature of 600 °C for 3 h, together with the complete decomposition of the residual organic compounds. Increasing the heating temperature led to particle growth, indicating that the crystallite size of the powders synthesized at 600 °C was 16 nm, which increased to 34 nm on heating at 700 °C and 45 nm on heating at 800 °C, respectively. The BMN nano powders obtained at 600 °C could be fully densified at a low temperature of 850 °C by spark plasma sintering (SPS), showing the uniform microstructure.