Microwave dielectric properties of low-temperature sinterable α-MoO3

The alpha-MoO3 ceramics were prepared by uniaxial pressing and sintering of MoO3 powder at 650 degrees C and their structure, microstructure, densification and sintering and microwave dielectric properties were investigated. The sintering temperature of alpha-MoO3 was optimized based on the best densification and microwave dielectric properties. After sintering at 650 degrees C the relative permittivity was found to be 6.6 and the quality factor was 41,000 GHz at 11.3 GHz. The full-width half-maximum of the Al, Raman mode of bulk alpha-MoO3 at different sintering temperatures correlated well with the Qf values. Moreover, the sintered samples showed a temperature coefficient of the resonant frequency of -25 ppm/degrees C in the temperature range from -40 to 85 degrees C and they exhibited a very low coefficient of thermal expansion of +/- 4 ppm/degrees C. These microwave dielectric properties of alpha-MoO3 will be of great benefit in future MoO3 based materials and their applications.