Structural features of glass-free Al2Mo3O12 ceramic with excellent microwave dielectric properties

The Al2Mo3O12 ceramic with monoclinic type is prepared at the sintering temperature as low as 750 degrees C, which exhibits excellent microwave dielectric properties of epsilon r = 4.99, Q x f = 49,579 GHz (f = 14.8 GHz), and tau f = -26 ppm/degrees C. The relationship between structure and characteristics is analyzed through the P-V-L chemical bond theory in depth, and the dielectric properties are investigated in combination with far-infrared spectroscopy. Results show that it is Mo-O bond that is responsible mainly for bond ionicity and dielectric polarizability, and structural stability as well. Based on the far-infrared reflectivity spectra and complicated dielectric function analysis, the calculated and measured results are in relative agreement using the classical damped oscillation mode, indicating that the mode at 80.23 cm-1 is dominant for the contribution to dielectric properties. This study gives an insight into the structural characteristic and provides a guide to further improve the microwave dielectric performance of Al2Mo3O12 ceramic.