Low-temperature sintered ZnNb2O6-CaTiO3 ceramics with near-zero τf

The phases, microstructure and microwave dielectric properties of ZnNb2O6-xCaTiO(3) ceramics with BaCu(B2O5) glass additions prepared by solid state reaction method were charactered by using X-ray diffraction, Scanning electron microscopy and Advantest network analyzer. The tau(f) of ZnNb2O6 was modified to near 0 ppm degrees C-1 by incorporating CaTiO3 with opposite tau(f) values on the basis of Lichtenecker empirical rule. The microwave dielectric properties of ZnNb2O6-xCaTiO(3) (x = 8.0 wt.%) samples with BaCu(B2O5) glass additives sintered in 900-1000 degrees C were investigated, and the results indicated that the behaviors of the epsilon(r) and Q x f were associated with the sintering temperature and the amount of BaCu(B2O5) glass. The sintering temperature of the ceramics was reduced to 950 degrees C from 1175 degrees C. Addition of 5.0 wt.% BaCu(B2O5) glass in ZnNb2O6-xCaTiO(3) (x = 8.0 wt.%) ceramics sintered at 950 degrees C showed excellent dielectric properties of epsilon(r) = 20.2, Q x f= 14,100 GHz (f= 7.3 GHz) and tau(f) = 0 ppm degrees C-1. Moreover, the material had a chemical compatibility with silver, which represented a promising candidate materials for low-temperature-co-fired ceramics applications. (C) 2014 Elsevier B.V. All rights reserved.