Structure, thermal and microwave dielectric properties of cold-sintered Li2MoO4-Al2O3 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 (kappa) in ceramics sintered at low temperatures is challenging. In this study, we employed the cold sintering process (CSP) to fabricate Li2MoO4-x%Al2O3 (0 <= x <= 80, in volume) ceramics under 200 MPa pressure at 150 degrees C. The Li(2)MoO(4)40%Al2O3 composite exhibited significantly enhanced kappa of 5.4 W<middle dot>m(-1)<middle dot>K-1, an 80% increase compared to pure Li2MoO4 ceramic with kappa of 3 W<middle dot>m(-1)<middle dot>K-1. At 40% Al2O3 content, the Li2MoO4Al2O3 ceramic demonstrated notable microwave properties (epsilon similar to 6.67, Qxf similar to 17,846 GHz, tau(f) similar to -105 x 10(-6) degrees C-1). Additionally, simulation of a microstrip patch antenna for 5 GHz applications using Li(2)MoO(4)20%Al2O3 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 Li2MoO4Al2O3 ceramics for microwave dielectric substrate.<br /> (c) 2024 The Authors. Published by Elsevier B.V. on behalf of The Chinese Ceramic Society. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).