Phase purifying and dielectric improvement in Zn2SiO4 ceramics via simply controlling the particle size of SiO2

Abstract

AbstractThe zinc orthosilicate, Zn2SiO4 ceramics, exhibit great potential as microwave dielectric materials due to their low dielectric constant and ultrahigh quality factor. The solid‐state synthesis of Zn2SiO4 ceramics often results in the presence of a secondary phase of ZnO, however, leading to significantly lower Q×f values. Cold‐isostatic‐pressing (CIP) and nonstoichiometry have been proven effective in purifying the Zn2SiO4 but need elaborate process and composition manipulation. In this work, it was found that the particle size of SiO2 plays a crucial role in purifying the Zn2SiO4 phase. Specially, nano‐sized SiO2 particles (15 and 30 nm) led to the formation of a ZnO secondary phase in synthesized Zn2SiO4 ceramics, while micro‐sized (2 and 10 µm) resulted in pure‐phase Zn2SiO4 with excellent microwave properties. Notably, when prepared with 10 µm SiO2 and sintered at 1 340°C, the resulting Zn2SiO4 exhibited outstanding microwave performances with a Q×f value of 122 570 GHz, a temperature coefficient of frequency τf of −51.9 ppm/°C, and a dielectric constant (εr) of 6.5. These findings highlight the importance of controlling particle size during synthesis to achieve desired material properties such as purity and excellent microwave performances.