High-Q×f CaWO4 ceramics sintered at low temperatures with the addition of Li2CeO3

Abstract

In this work, CaWO4 ceramics with high Q×f levels were successfully sintered at temperatures lower than 950 °C with the additions of very small amounts of Li2CeO3 (i.e., 0.1–2.0 wt.%). CaWO4 + x wt.% Li2CeO3 ceramic samples were found to be consisted of a single sheelite phase with relatively high density levels and homogenous microstructures. The ceramic samples exhibited excellent microwave dielectric properties, for instance, the specimen with 0.5 wt.% Li2CeO3 sintered at 725 °C for 4 h showed the properties of er = 9.9, Q×f = 69000 GHz, and τf = −63 ppm/°C. Moreover, it was found that there was no apparent reaction between the ceramic sample and Ag electrode during the sintering process. Therefore, Li2CeO3 has been proofed to be a highly effective sintering additive of CaWO4 ceramics, which is a promising candidate material for low temperature co-fired ceramic (LTCC) technology.