Structural, microstructural, and microwave dielectric properties of (Al1-xBx)2Mo3O12 ceramics with low dielectric constant and low dielectric loss for LTCC applications

The (Al1-xBx)2Mo3O12 ceramics with double phases were prepared by solid-phase sintering method at the temperature from 725 to 800 degrees C for LTCC application. Through XRD pattern and Rietveld refinement analysis, it was confirmed that the (Al1-xBx)2Mo3O12 composition consists of the coexistence of double phase (the monoclinic structure of the P21/a space group and the orthorhombic structure of the Pnca space group), and the orthorhombic phase was increased with boron substitution. The microwave dielectric properties of the (Al1xBx)2Mo3O12 ceramic series were impacted by double-phase formation (crystal structure ratio), which increases the densification and grain uniformity. With the boron substitution, the (Al1-xBx)2Mo3O12 ceramic series demonstrate outstanding microwave dielectric properties (er = 4.04, Q x f = 35870 GHz @ 15 GHz, z & INT; = 4.2 ppm/degrees C) with high relative density (prel & AP; 98.84%) and thermal conductivity lc = 0.88 W/m.K for x = 0.3 at 775 degrees C, indicate that it is a promising candidate for LTCC substrate material.