Microwave dielectric properties of Li₂(M²⁺) ₂Mo₃O₁₂ and Li₃(M ³⁺)Mo₃O₁₂ (M=Zn, Ca, Al, and In) lyonsite-related-type ceramics with ultra-low sintering temperatures

In this work, the Li₂(M²⁺)₂Mo ₃O₁₂ and Li₃(M³⁺)Mo ₃O₁₂ (M=Zn, Ca, Al, and In) lyonsite-related structures were prepared using a solid-state reaction method. Single-phase lyonsite materials were formed for the following compositions Li₂Zn ₂Mo₃O₁₂, Li₃AlMo₃O ₁₂, and Li₃InMo₃O₁₂ ceramics. Whereas, the Li₂Ca₂Mo₃O₁₂ batched compositions produced Li₂MoO₄ and CaMoO₄ phases. All the four ceramics did not react with Ag and Al powders at their optimal sintering temperatures, which will permit the possibility of cofired electrodes with these metallurgies. The Li₂Zn₂Mo ₃O₁₂ ceramic can be sintered at 630°C with a relative permittivity of 11.1, a Q×f value of ∼70 000 GHz, and a temperature coefficient of -90 ppm/°C at 14.6 GHz. The Li₃AlMo ₃O₁₂ ceramic sintered at 570°C has a relative permittivity of 9.5, a Q×f value of ∼50 000 GHz, and a temperature coefficient of -73 ppm/°C at 14.1 GHz. The Li₃InMo ₃O₁₂ ceramic sintered at 630°C has a relative permittivity of 9.8, a Q×f value of ∼36 000 GHz, and a temperature coefficient of -73 ppm/°C at 15.0 GHz. These ceramics are a good candidate for the expanding family of ultra-low temperature cofired ceramic technologies, for filter and substrate applications at the high-frequency range.