Cold sintered temperature stable xLi₂MoO₄-(1-x)(LiBi)_0.5MoO₄ microwave dielectric ceramics

Temperature stable xLi₂MoO₄-(1-x)(LiBi)_0.5MoO₄ (x = 0, 40, 50, 60, 70, 100 vol%) microwave dielectric ceramics obtained by cold sintering process (CSP) under a mild sintering condition (120 ℃/30 min/200 MPa) are introduced in this work. The XRD, SEM, and Raman analysis indicate the coexistence of Li₂MoO₄ and (LiBi)_0.5MoO₄ phases. Li₂MoO₄-(LiBi)_0.5MoO₄ ceramics are compatible with Ag and Al electrode materials under cold sintering condition. The specimens exhibit high relative densities and good microwave dielectric properties (relative permittivities: 31.5–5.5; Q×f values: 1900 - 18,500 GHz; TCF values: from +144 ppm/℃ to −106 ppm/℃), in particular, TCF = +0.7 ppm/℃ can be obtained in the case of x = 50 vol%. The extrapolated microwave dielectric properties obtained by the fitted infrared reflectivity spectrum are close to the measured data, revealing that the dielectric responses of cold sintered Li₂MoO₄-(LiBi)_0.5MoO₄ ceramics in the microwave range are dominated by the polar optical phonons.