Effect of glass additions on the sintering behaviors and electrical microwave properties of BaO-Nd2O3-Sm2O3-TiO2 ceramics

Abstract

The effect of Al2O3-doped silica glass (AS-glass) addition on the structure and dielectric properties of the BaO-Nd2O3-Sm2O3-TiO2 (BNST) microwave materials was investigated. This BNST material has a dielectric constant (k) of 80 and a quality factor (Q x f) of 6000 GHz when sintered at 1350degreesC for 2 h. Both the microstructure and the microwave dielectric characteristics were determined as a function of the sintering temperature and glass content. A Q x fas high as 8700 GHz was achieved in ceramics added with 20 wt% glass, however, the k value drops to 30. The high Q x 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. (C) 2004 Kluwer Academic Publishers.