Low-temperature preparation and structural-property characterization of Al2Mo3O12

The prevalent challenge associated with microwave dielectric ceramics is their excessively high sintering temperatures , underscoring the pressing need to develop materials that not only possess low-temperature sintering capabilities but also exhibit exceptional microwave dielectric properties . This study systematically investigates the synthesis of aluminum molybdate (Al 2 Mo 3 O 12 ) ceramics through an innovative combination of the non-hydrolytic sol-gel method and mechanochemical processing, with the objective of achieving low-temperature sintering. The sintering behavior and microwave dielectric properties of the resultant ceramics were analyzed over a temperature range of 675 °C to 775 °C. The findings demonstrate that the formation of =Al-O-Mo= oxygen bridge bonds during the non-hydrolytic stage effectively reduces the energy barrier associated with bond-breaking and reinvention. Furthermore, the application of ball milling significantly enhances the reactivity of the powder, thus facilitating a reduction in the synthesis temperature. Notably, at a sintering temperature of 725 °C, the aluminum molybdate ceramics exhibit commendable sintering characteristics and attain optimal densification. At this temperature, the ceramics also demonstrate outstanding microwave dielectric properties, characterized by a dielectric constant (ε r ) of approximately 6.9, a quality factor ( Q×f ) of around 76,600 GHz, and a frequency temperature coefficient (TCF) of approximately -31.9 ppm/°C. These results indicate that aluminum molybdate ceramics represent a promising candidate for microwave communication applications, particularly within the realm of low-temperature co-fired ceramics (LTCC), illustrating their significant potential for future advancements in this field.