Low-temperature sintering and microwave dielectric properties of CaMoO4 ceramics for LTCC and ULTCC applications

Abstract

Low-temperature co-fired ceramic (LTCC) technology can meet the requirements of device miniaturization and integration. In this work, a novel series of CaMoO4 + x wt.% Li2MoO4 (CMO+ xLMO, x = 0.0–2.5) microwave dielectric ceramics were prepared. The sintering temperature of CMO ceramic significantly declines from 1050 °C to 600 °C by adding a small amount of LMO. A dissolution-precipitation process at the grain boundary has been demonstrated to be the mechanism for low-temperature sintering through transmission electron microscopy analysis. The low-temperature sintered CMO ceramics present excellent microwave dielectric properties, e.g. CMO+ 1.0 wt.% LMO ceramics sintered at 600 °C, εr ∼ 14.4, Q×f ∼ 13,060 GHz, τƒ ∼ − 41.0 ppm/°C; CMO+ 2.5 wt.% LMO ceramics sintered at 700 °C, εr ∼ 15.1, Q×f ∼ 16,122 GHz, τƒ ∼ − 43.8 ppm/°C, which show great potentials in both LTCC and ULTCC applications.