Effect of Li2MoO4 on Cold-Sintered CaTiO3 Ceramic Composite: Densification Mechanism and Microwave Dielectric Properties

Ceramic composites of CaTiO3-Li2MoO4 were successfully fabricated using the cold sintering process (CSP), and their microwave dielectric properties were systematically investigated. Densification of CaTiO3 ceramics typically requires high-temperature sintering above 1200°C, resulting in substantial energy consumption. As the CSP can effectively address these challenges, it has emerged as a transformative low-temperature densification technique, offering both reduced energy consumption and scalable fabrication through relatively simple processing conditions. In the present study, a CaTiO3-Li2MoO4 (with 5–25 wt.% Li2MoO4) ceramic composite was prepared, and its phase composition, microstructural evolution, vibrational spectroscopic characteristics, and dielectric properties were systematically examined as a function of water-soluble Li2MoO4 content. Notably, a relative densification of ρr = 92.4% was achieved at 220°C and 350 MPa for 1 h, indicating a distinctive densification mechanism governed by a dissolution-precipitation process at ceramic interfaces. The optimized composite exhibits a dense microstructure with strong interfacial bonding and promising microwave dielectric properties of εr = 39.7, tan δ = 1.7 × 10−3, Q×f = 2557 GHz, and τf = +180 ppm/°C. These results demonstrate that CSP enables the low-temperature processing of CaTiO3-Li2MoO4 ceramic composites while achieving competitive dielectric performance, making it a promising approach for miniaturized millimeter-wave devices in next-generation electronic systems.