Effect of Different Crystallization Temperature on Dielectric Properties of BaO–SrO–PbO–TiO 2 –SiO 2 –Nb 2 O 5 Glass-Ceramic Composites

Nanocomposite dielectrics in 2.5BaO–18.5SrO–8.5PbO–8TiO2–20SiO2–20Nb2O5 system were prepared via melt-quenching followed by controlled crystallization. X-ray diffraction studies revealed that Pb2Nb2O7, (Ba,Sr,Pb)Nb2O6 and (Sr,Pb)TiO3 phases formed from the as-quenched glass annealed in the temperature range from 800 to 1000 °C. Pb2Nb2O7, (Ba,Sr,Pb)Nb2O6 and (Sr,Pb)TiO3 crystallized at 800 °C and then Pb2Nb2O7 disappears at 900 °C, while PbNb2O6 formed at 900 °C. The microstructural observation showed that randomly oriented, the nanometer-sized crystalline grains were found with residual glass concentrated at phase boundaries. Meanwhile, the crystalline grain of the samples grew with the increase in crystallization temperature. And the dielectric constant is enhanced with the increasing crystallization temperature as well. The dielectric constant of the nanocomposites crystallized at different temperatures showed good temperature and electric field stability. In particular, the sample had a high dielectric constant of 900 after crystallized at 1000 °C, and the dielectric loss still remained at a low level of 0.0042, which is expected to be used as a promising candidate material for high voltage ceramic capacitor applications.