A novel ultralow-loss Sr2CeO4 microwave dielectric ceramic and its property modification

A new ultralow-loss Sr₂CeO₄ microwave dielectric ceramic was prepared via a conventional solid-state method. The X-ray diffraction and Rietveld refinement results demonstrate that pure-phase Sr₂CeO₄ ceramics belong to the orthorhombic structure with a Pbam space group. Scanning electron microscopy analysis reveals dense and homogeneous microstructure. Optimum microwave dielectric properties of ε_r = 14.8, Q × f = 172,600 GHz (9.4 GHz) and τ_f = -62 ppm/°C were obtained as it was sintered at 1270 °C for 4 h. In addition, the substitution of a few amount of Ti⁴⁺ for Ce⁴⁺ was found to have significant influences on the grain morphology, sintering behavior, phase structure and microwave dielectric properties. Among them, the Sr₂Ce_0.65Ti_0.35O₄ ceramic sintered at 1350 °C for 4 h demonstrates near-zero τ_f of -1.8 ppm/°C, ε_r of 20.7 and Q×f of 115,550 GHz (8.1 GHz) because of its two-phase structure, showing large application potentials.