Correlation between structure and microwave dielectric properties of low-temperature-fired Mg2SiO4 ceramics

Abstract

Mg2SiO4–LiF ceramics were fabricated via a conventional solid-state process and sintered at 900 °C. The secondary phase, Li2SiO3, was observed with ≤6 wt% LiF, and the Li2MgSiO4 phase was detected with ≥8 wt% LiF. The relative density and secondary phase can account for the decrease in the εr with an increase in LiF. The degree of crystallization, unit cell volume, secondary phase, and microstructure correlated with the Q × f values. The value of the τf was related to the distortions in the Mg(1)O6 octahedron and the secondary phase. The sample exhibited excellent properties for Mg2SiO4–8 wt% LiF with εr = 6.1, Q × f = 109719 GHz, and τf = − 61 ppm/°C. The temperature stability of the Mg2SiO4–8 wt%LiF–6 vol%CaTiO3 ceramics was obtained with εr = 7.1, Q × f = 31091 GHz and τf = − 2.0 ppm/°C. Mg2SiO4–LiF–CaTiO3 ceramics provide excellent chemical compatibility with Ag.