Crystal Structure and Microwave Dielectric Property of xMgO-SiO2 (x = 1~2) System for 5G Applications

Mg2SiO4and MgSiO3ceramics with superior microwave dielectric properties are considered to be promising candidates for 5G applications. However, a slight deviation from the stoichiometric Mg/Si ratio will significantly influence their microwave dielectric properties, which will hinder their practical applications. In this work, thexMgO-SiO2(x= 1~2) ceramics were synthesized by a solid-state reaction method. The influence of the Mg/Si ratioxon the crystalline phase, microstructure, and microwave dielectric properties was investigated through X-ray diffraction (XRD), a scanning electron microscope (SEM), and the resonant cavity method. The XRD patterns revealed the coexistence of Mg2SiO4and MgSiO3within thexrange of 1~2, which was further demonstrated by the energy-dispersive X-ray spectra. The SEM images show a typical polycrystalline morphology of ceramics with an inhomogeneous grain size distribution. It is found that the microwave dielectric properties fluctuate at both sides of thexrange while those remain relatively stable with minor changes at the intermediate components, indicating an obvious low composition dependence helpful for practical applications. Further, a demonstrator of a microstrip patch antenna for 5G applications using the 1.5MgO-SiO2ceramic was designed and fabricated, and a return loss of −16.2 dB was demonstrated, which demonstrated the potential applications.Keywords:MgO-SiO2systems;5G application;microwave dielectric ceramics;phase composition