Effects of BaCu(B2O5) addition on phase transition, sintering temperature and microwave properties of Ba4LiTa3O12 ceramics

Polycrystalline sample of Ba4LiTa3O12 is synthesized in the temperature range of 1300-1350 degrees C by the conventional solid state reaction method, and a phase transition from cubic to hexagonal perovskite is observed between 1300 degrees C and 1350 degrees C. Hexagonal phase of Ba4LiTa3O12 obtained at 1350 degrees C could be stabilized at considerably lower temperature (similar to 925 degrees C) with BaCu(B2O5) (BCB) addition. BCB addition effectively improves the densification of Ba4LiTa3O12 ceramic at low temperature and induces only a limited degradation of the microwave dielectric properties. A dense ceramic with a epsilon(r) of 25.5, a high Q(u) x f of 32,600 GHz, and a low tau(f) of 23.6 ppm/degrees C is obtained for the 4 wt.% of BCB-added Ba4LiTa3O12 sintered at 925 degrees C. Moreover, Ba4LiTa3O12 ceramics added 1-5 wt.% of BCB have a chemical compatibility with silver electrode at 925 degrees C, which might be an attractive promising candidate for LTCC application. (C) 2010 Elsevier B.V. All rights reserved.