Chemical bond and dielectric response of Yb₂Si₂O₇ ceramic with low dielectric constant at GHz and THz

The exploration of high-performance dielectric ceramics with dielectric constants lower than 10 is of great significance for the next generation of wireless communication. In this study, we reported the Yb₂Si₂O₇ (YSO) dielectric ceramics synthesized using a facile solid-state reaction technique. X-ray diffraction (XRD) and transmission electron microscopy (TEM) characterization confirmed that YSO ceramics had a monoclinic structure. At a sintering temperature of 1500 °C, the sintered sample reached a maximum relative density of 96% and demonstrated the best dielectric properties: dielectric constant (ε_r) = 7.57, Q×f = 78,645 GHz (Q is quality factor, and f is the resonant frequency of 13.5 GHz), andtemperature coefficient of the resonant frequency (τ_f) = −13.5 ppm/°C. Moreover, Raman analysis revealed that the Si–O bond dominated the lattice vibration, and the full width at half maximum (FWHM) of the strong peak at 922 cm⁻¹ was inversely proportional to the Q×f value. According to the Phillips–van Vechten–Levine (P–V–L) theory, the values of Q×f and τ_f are affected primarily by the Si–O bond, while ε_r is influenced mainly by the Yb–O bond. YSO ceramics demonstrated excellent dielectric properties in the terahertz band (ε_r = 8.13, Q×f = 112,758 GHz), making them promising candidates for future applications in the terahertz band.