Achieving Near-Zero TCF and High Quality Factor in Li₂TiO₃-Based Dual-Phase Ceramics via Synergistic Phase and...

Next-generation communication systems urgently demand microwave dielectric ceramics that combine ultra-low dielectric loss with exceptional thermal stability. However, overcoming the persistent trade-off between a high quality factor (Q) and a near-zero temperature coefficient of resonant frequency (TCF) remains a formidable challenge. Here, we report a synergistic design strategy that integrates (Ga_1/2Nb_1/2)⁴⁺ substitution with LiF-assisted microstructural engineering to resolve this dilemma in Li₂TiO₃ ceramics. The synergistic interaction drives a phase evolution from the monoclinic phase (positive TCF) toward the cubic phase (negative TCF), constructing a dual-phase structure that achieves near-zero TCF through self-compensation. Simultaneously, LiF-assisted liquid-phase sintering promotes densification at lower temperatures, thereby significantly reducing dielectric loss. Remarkably, the optimized Li₂Ti_0.95(Ga_1/2Nb_1/2)_0.05O₃ - 2 wt.% LiF ceramic demonstrates exceptional microwave dielectric properties, featuring a high Q × f value of 129 390 GHz (at 7.3 GHz) and a near-zero TCF of +8.5 ppm/°C. The proposed synergistic strategy provides a robust pathway for developing high-performance microwave dielectric ceramics for wireless communication applications.