High- Q enstatite microwave/terahertz dielectric ceramics modulated by phase transition and lattice distortion

作者：Yutian Lu, Weijia Guo, Chongyang Zhang, Hui Zhang, Zhenxing Yue · 发表于：Journal of Advanced Ceramics · 年份：2025 · DOI：10.26599/jac.2025.9221053 · 被引用次数：16 · 研究领域：Microwave Dielectric Ceramics Synthesis、Microwave Engineering and Waveguides、Ferroelectric and Piezoelectric Materials

The rapid development of fifth-/sixth-generation telecommunication technologies has increased the demand for silicate ceramic materials with low permittivity and low dielectric loss. However, few silicate ceramics with ultrahigh Q × f values (≥ 200,000 GHz) have been developed to date. In this study, a slight substitution of Ge 4+ ions in MgSi 1− x Ge x O 3 (MSG x , x = 0 to 0.6) ceramics caused a phase transition from clinoenstatite ( x = 0) to orthoenstatite ( x = 0.2), and the Q × f value increased from 70,600 GHz to 148,800 GHz. Following the phase transition, the cations change from a “compressed” state to a “rattle” state, and the lattice distortion continues to rise with x , resulting in the optimal microwave dielectric properties ( ε r = 7.21, Q × f = 259,300 GHz) of the MgSi 0.5 Ge 0.5 O 3 ceramics. Significant discrepancies in the dielectric properties are found in the microwave and terahertz bands. There is an anomalous increase in ε r and a decrease in the Q × f value in the terahertz band, which is due to the change in polar phonon modes revealed by the terahertz time-domain spectra. Consequently, MgSi 0.7 Ge 0.3 O 3 ceramics display superior dielectric properties, with ε r = 7.02, Q × f = 191,300 GHz in the terahertz band. These novel materials have the potential to serve as promising dielectric materials for future microwave or terahertz mobile communication systems.