Effects of LiMoVO₆ on phase composition and microwave dielectric properties of ultra-low firing Al₂Mo₃O₁₂ ceramics

In this work, reducing sintering temperature while synergistically improving temperature stability in Al₂Mo₃O₁₂ ceramic has been achieved with the assistance of the LiMoVO₆ phase. The LiMoVO₆ does not react with the Al₂Mo₃O₁₂ phase, showing excellent chemical compatibility. Both intrinsic and extrinsic factors contribute to the development of microwave dielectric properties of (1-x)Al₂Mo₃O₁₂-xLiMoVO₆ (x = 0.205) ceramic. Dielectric polarization, relative density, phase constitutions, and contents greatly influence the change of ε_r value; while the Q × f value is more sensitive to the technological process for the solid-state method inevitably introducing grain growth and grain boundaries, resulting in grain boundary losses. Benefitting from the temperature compensation effect of the LiMoVO₆ phase, the τ_f value can be effectively regulated based on the mixture rule. When sintered at 600 °C, the (1-x)Al₂Mo₃O₁₂-xLiMoVO₆ (x = 0.205) ceramic shows a low ε_r value of 7.05, a Q × f value of about 8543 GHz (@13.4 GHz), and a τ_f value of ca. − 14.2 ppm/^oC, which is suitable for applying in ULTCC technology.