Low‐temperature sintering of microwave ceramics with high Qf

Microwave ceramic with low‐sintering temperature is one of the most important classes of material to realize the integration and miniaturization of microwave devices. In this work, in order to simultaneously realize low‐temperature sintering and good microwave dielectric properties, CaMgSi2O6–xLiF was sintered at various sintering temperatures using LiF as a sintering aid. In comparison to CaMgSi2O6 (x = 0) sintered at 1250°C, desirable microwave dielectric properties of εr = 7.45, Qf = 64 800 GHz, and τf = −34 ppm/°C and good chemical compatibility with the Ag electrodes, were achieved sintered at 900°C when adding 2 wt% LiF into CaMgSi2O6. Furthermore, a secondary phase, Li2MgSiO4, occurred at x ≥ 1 wt%, and the densest microstructure was obtained at the x value of ~2 wt%. We propose that the high Qf value and the low‐sintering temperature were obtained through moderate LiF addition, which promotes densification and provides Li as the acceptor dopant. By further verifying in Mg2SiO4 ceramic, our study demonstrates that the approach of adding LiF can realize low‐temperature sintering without jeopardizing the excellent microwave dielectric properties, and can potentially be applied in a wide range of low‐temperature sintering of electronic ceramics.Ministry of Education (MOE)Accepted versionSpecial Projects on Science and Technology of Guizhou Province, Grant/ Award Number: [2016]3011; National Key Research and Development Plan, Grant/Award Number: 2016YFA0300801; Academic Research Fund Tier 1 from Singapore Ministry of Education and Nanyang Assistant Professorship Grant, Grant/Award Number: RG108/17; Science and Technology Department of Sichuan Province, Grant/Award Number: 2015JQ0031, 2016JQ0016; National Natural Science Foundation of China, Grant/Award Number: 51772047, 61471096, 6177110