Ultra-low sintering temperature ceramic composites of CuMoO4 through Ag2O addition for microwave applications

The present paper presents ceramic composites with ultralow sintering temperature of 500 °C and densification of 96% by adding small amount (0.5, 1 and 2 wt%) of Ag2O to CuMoO4 by simple mixing method. The effect of Ag2O addition on the structure, microstructure, sintering and thermal as well as microwave dielectric properties of CuMoO4 is also studied. The reduction in the sintering temperature is due to the formation of trace amount (1.4%) of copper silver molybdate (Cu2Ag2(MoO4)3) as observed from Rietveld refinement analysis as well as backscattered SEM image. Doping has very little influence on the structure and coefficient of thermal expansion that is about 4.7-5.2 ppm/°C. The composites sintered at 500 °C exhibit relative permittivity of about 8-9, quality factor (Qf) of 26000-37000 GHz at 12 GHz, temperature coefficient of resonant frequency of -31-33 ppm/°C and are compatible with Al electrode. The present work results in obtaining well-densified ultralow temperature cofired ceramic composites at low sintering temperature without much structural change and good thermal properties but with different dielectric properties by small doping. These composites can be used as low cost candidates for wide range of microwave applications like multilayer packages and substrates owing to the low energy required during processing and hence can pave way to the advancement of electronic materials.