Structure, thermal and microwave dielectric properties of cold-sintered Li2MoO4Al2O3 ceramic

Dielectric ceramics are essential components in communication systems that operate within the microwave frequency range. In high-density packages, dielectric substrates ceramics must possess high thermal conductivity to efficiently dissipate heat. However, achieving adequate thermal conductivity ( κ ) in ceramics sintered at low temperatures is challenging. In this study, we employed the cold sintering process (CSP) to fabricate Li 2 MoO 4 - x %Al 2 O 3 (0≤ x ≤ 80, in volume) ceramics under 200 MPa pressure at 150 °C. The Li 2 MoO 4 40%Al 2 O 3 composite exhibited significantly enhanced κ of 5.4 W·m −1 ·K −1 , an 80% increase compared to pure Li 2 MoO 4 ceramic with κ of 3 W·m −1 ·K −1 . At 40% Al 2 O 3 content, the Li 2 MoO 4 Al 2 O 3 ceramic demonstrated notable microwave properties ( ε ∼ 6.67, Q×f ∼ 17,846 GHz, τ f ∼ −105 × 10 −6 °C -1 ). Additionally, simulation of a microstrip patch antenna for 5 GHz applications using Li 2 MoO 4 20%Al 2 O 3 ceramic as dielectric substrate via Finite Element Simulation software showed excellent performance, with radiation efficiency exceeding 99% and low return loss ( S 11 < −30 dB) at both 4.9 GHz and 28.0 GHz center frequencies. These findings underscore the suitability of Li 2 MoO 4 Al 2 O 3 ceramics for microwave dielectric substrate. • Li 2 MoO 4 Al 2 O 3 ceramics was prepared by cold sintering process at a low temperature of only 150 °C. • Obtained ceramic shown a notable microwave property and a high thermal conductivity of 5.4 W m −1 ·K −1 . • The microstrip patch antenna was designed and simulated.