High-performance SiO2-Sr3(PO4)2 low-εr dielectric ceramics for MW/THz applications

Abstract

We developed high-performance SiO2-based low-εr microwave dielectric composites via adding Sr3(PO4)2 and investigated their phase assemblages, sintering behaviors, microwave dielectric properties, thermal expansion coefficients (CTE), and mechanical strengths in this paper. Adding Sr3(PO4)2 into SiO2 could successfully suppress the occurrence of microcracks in SiO2, tune the values of both temperature coefficient of resonant frequency (τf) and CTE, and enhance the flexural strength of the composite simultaneously. The composite with 22.5 % volume fraction (Vf) of Sr3(PO4)2 exhibits excellent combined properties with a low-εr (∼5.35), high Q×f value ( ∼73,717 GHz), near-zero τf value(∼ −1.1 ppm/°C), suitable high CTE value (∼17 ppm/°C), and acceptable high flexural strength (∼85Mpa) after sintering at the temperature of 1150°C/3 h.