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Journal of Advanced Ceramics

Keywords

low permittivity, low-temperature sintering, crystal structure, microwave dielectric properties

Abstract

In this study, low-temperature fired CaMg1-xLi2xSi2O6 microwave dielectric ceramics were prepared via the traditional solid-state reaction method. In this process, 0.4 wt% Li2CO3-B2O3-SiO2- CaCO3-Al2O3 (LBSCA) glass was added as a sintering aid. The results showed that ceramics consisted of CaMgSi2O6 as the main phase. The second phases were CaSiO3 always existing and Li2SiO3 occurring at substitution content x > 0.05. Li+ substitution effectively lowered sintering temperature due to 0.4 wt% LBSCA and contributed to grain densification, and the most homogeneous morphology could be observed at x = 0.05. The effects of relative density, the second phase, and ionic polarizability on dielectric constant (εr) were investigated. The quality factor (Q × f ) varied with packing fraction that concerned the second phase. Moreover, the temperature coefficient of the resonant frequency (τf) was influenced by MgO6 octahedral distortion and bond valence. Excellent dielectric properties of the CaMg1-xLi2xSi2O6 ceramic was exhibited at x = 0.05 with εr = 7.44, Q × f = 41,017 GHz (f = 15.1638 GHz), and τf = −59.3 ppm/℃ when sintered at 900 ℃. It had a good application prospect in the field of low-temperature co-fired ceramic (LTCC) substrate and devices.

Publisher

Tsinghua University Press

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