Low-temperature sintering and microwave dielectric properties of CaMg1−xLi2xSi2O6 (x = 0−0.3) ceramics
In this study, low-temperature fired CaMg 1− x Li 2 x Si 2 O 6 microwave dielectric ceramics were prepared via the traditional solid-state reaction method. In this process, 0.4 wt% Li 2 CO 3 -B 2 O 3 -SiO 2 -CaCO 3 -Al 2 O 3 (LBSCA) glass was added as a sintering aid. The results showed that ceramics consisted of CaMgSi 2 O 6 as the main phase. The second phases were CaSiO 3 always existing and Li 2 SiO 3 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 (ε r ) were investigated. The quality factor ( Q × f ) varied with packing fraction that concerned the second phase. Moreover, the temperature coefficient of the resonant frequency (τ f ) was influenced by MgO 6 octahedral distortion and bond valence. Excellent dielectric properties of the CaMg 1− x Li 2 x Si 2 O 6 ceramic was exhibited at x = 0.05 with ε r = 7.44, Q × f = 41,017 GHz ( f = 15.1638 GHz), and τ f = −59.3 ppm/°C when sintered at 900 °C. It had a good application prospect in the field of low-temperature co-fired ceramic (LTCC) substrate and devices.
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