Synergistic enhancement of mechanical and microwave dielectric properties in MgGa2O4-based ceramics via cocktail effect

To address the longstanding challenge of achieving cooperative optimization of thermal stability and mechanical properties in spinel ceramics, a high-entropy strategy was introduced into the MgGa 2 O 4 spinel system. Ceramics with varying configurational entropies were synthesized via a solid-state reaction at 1350–1450 °C. Results demonstrate that increasing configurational entropy significantly enhances lattice distortion and microstrain, successfully tuning the temperature coefficient of resonant frequency to near-zero (1.48 ± 1.55 ppm/°C). Simultaneously, elevated diffusion barriers trigger a sluggish diffusion effect, inhibiting grain growth. Furthermore, oxygen vacancies and chemical short-range order synergistically construct a three-dimensional dislocation-pinning network, substantially boosting flexural strength to 213.05 ± 7.03 MPa. Driven by the cocktail effect, this synergy achieves the simultaneous optimization of thermal stability and mechanical properties. This work reveals the underlying physical mechanisms of the four core high-entropy effects, providing a novel design strategy for next-generation microwave components with high flexural strength and excellent thermal stability.