Effect of glass additions on the sintering behaviors and electrical microwave properties of Bao-Nd₂O₃-Sm₂O ₃-TiO₂ ceramics

The effect of Al₂O₃-doped silica glass (AS-glass) addition on the structure and dielectric properties of the BaO-Nd ₂O₃-Sm₂O₃-TiO₂ (BNST) microwave materials was investigated. This BNST material has a dielectric constant (k) of 80 and a quality factor (Q × f) of 6000 GHz when sintered at 1350 °C for 2h. Both the microstructure and the microwave dielectric characteristics were determined as a function of the sintering temperature and glass content. A Q × f as high as 8700 GHz was achieved in ceramics added with 20 wt% glass, however, the k value drops to 30. The high Q × f value is attributed to the improved densification of the dielectric when glass is added. Results of X-ray diffraction experiments indicate that glass addition enhances the growth in the longitudinal direction of the columnar crystal and a preferred (002) orientation. The presence of columnar structure plays an important role in the improvement of the microwave dielectric properties.