Densification, microstructure and microwave dielectric properties of ultra-low fire BaTe4O9–TiTe3O8 ceramic composites

In this study, BaTe4O9–TiTe3O8 ceramic composites with various amounts of TiTe3O8 were prepared, and the densification, microstructural evolution, and dielectric properties of the ultra-low fire ceramic composites were characterized. With the addition of TiTe3O8, the ceramic composites were densified at 575 °C with the maximum densities ranging from 93% to 96% of theoretical density. Except the BaTe4O9 and TiTe3O8 phases, no other second phase was observed in the XRD results. The change in the microstructures caused by the increase of TiTe3O8 content appeared to be insignificant. Wide grain size distributions with angular grains in the range of 1–4 μm were observed for all cases. The best dielectric properties – ɛr value of 25, Q × f value of 19,340 GHz, and τf value of −2.7 ppm/°C – were obtained for BaTe4O9–40 wt% TiTe3O8 ceramic composite sintered at 575 °C, qualifying the ultra-low fire composites for use in the application of ceramic resonators.