Effect of Na 2W 2O 7 addition on low-temperature sintering and microwave dielectric properties of CaWO 4

Abstract

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