Ultra-low temperature sintering and microwave dielectric properties of a novel temperature stable Na2Mo2O7-Na0.5Bi0.5MoO4 ceramic

The novel ultra-low temperature sintering (1-x)Na2Mo2O7-xNa0.5Bi0.5MoO4 ceramics have been obtained via solid-state reaction method for passive integration use. The Na2Mo2O7 and Na0.5Bi0.5MoO4 crystal phases are found to be compatible with each other from the results of XRD and SEM-EDS. With the x value changing from 0.36 to 1.00, the εr increases from 16.0 to 32.0 and the τf value varies from −58 to 47 ppm/°C. At x = 0.75, the 0.25Na2Mo2O7-0.75Na0.5Bi0.5MoO4 ceramic sintered at an ultra-low sintering temperature of 580 °C can be densified (>96%) and possesses good microwave dielectric properties of an εr of 24.0, a Q × f value of 13,000 GHz (at 6.2 GHz), and a τf value of 3 ppm/°C. The theoretical εr and τf of the (1-x)Na2Mo2O7-xNa0.5Bi0.5MoO4 composites were calculated using the mixing law and in accordance with the measured values.