Structure, composition, microwave dielectric properties and improved ultra-low temperature sintering characteristics of Lyonsite structural Li₂Mg₂Mo₃O₁₂ ceramic

(1-x)Li₂Mg₂Mo₃O₁₂-xTiO₂ (x = 0.1–0.5) composite ceramics are prepared by solid-state sintering process. And the structure, composition, microwave dielectric properties and ultra-low temperature sintering characteristics are studied. The result of two-phase (Li₂Mg₂Mo₃O₁₂ and TiO₂) coexistence is definitely identified through XRD, mapping and Raman analysis along different regions. Furthermore, as the sintering temperature increases, the enhanced degree of densification plays a positive role in determining microwave dielectric properties. Sintering additives are used to lower sintering temperature of 0.6Li₂Mg₂Mo₃O₁₂-0.4TiO₂ composite ceramics, where 1 wt% H₃BO₃ is applied to reduce the temperature from 750 °C to 700 °C and maintain excellent microwave dielectric characteristics. The cooling mechanism of sintering aids are also thoroughly studied. In all, 0.6Li₂Mg₂Mo₃O₁₂-0.4TiO₂ composite ceramic with 1 wt% H₃BO₃ sintered at 700 °C displays excellent microwave dielectric properties (ε_r∼11.27, Q × f ∼43056 GHz, τ_f ∼ -3 ppm/°C). It can be served as a pioneering candidate in applications of ULTCC (ultra-low temperature co-fired ceramic).