Effect of Na2W2O7 addition on low-temperature sintering and microwave dielectric properties of CaWO4

Effects of Na2W2O7 addition on low-temperature sintering, microstructure and microwave dielectric properties of CaWO4 were studied by X-ray diffraction (XRD), scanning electron microscopy (SEM) and microwave dielectric resonator methods in this paper. The CaWO4 material could be sintered into a dense ceramic (-96% theoretical density) at 850 degrees C/2 h without affecting its microwave dielectric properties greatly by adding appropriate amount of Na2W2O7. The XRD results showed that CaWO4 main phase with trace amount of Na2W2O7 second phase was observed in (1-x) CaWO4-xNa(2)W(2)O(7) (0<x <= 0.04) ceramics. The chemical compatibility of 0.96CaWO(4)-0.04Na(2)W(2)O(7) ceramic with silver (Ag) powders was also investigated. The Ag showed inert behavior with 0.96CaWO(4)-0.04Na(2)W(2)O(7) ceramic when co-fired at 875 degrees C for 2 h. (C) 2010 Elsevier B.V. All rights reserved.