Effect of Co and Sr substitution on the microwave dielectric properties of CaMg0.9Li0.2Si2O6-based ceramics for LTCC application

In this work, two low-temperature co-fired silicate ceramics (CaMg 0.9- x Li 0.2 Co x Si 2 O 6 , x  = 0.15–0.75, CMLCS; CaMg 0.9-y Li 0.2 Sr y Si 2 O 6 , y  = 0, 0.05, 0.1–0.5, CMLSS) were synthesized via solid-state reaction method with 0.5 wt%LBSCA glass addition. CMLCS and CMLSS were densely sintered at 925 °C, and had good chemical compatibility with silver. Optimal microwave dielectric properties ( ε r  = 6.71, Q×f  = 30124 GHz, and τ f  = −79.06 ppm/°C) and ( ε r  = 6.78, Q×f  = 32530 GHz, and τ f  = −52.99 ppm/°C) were obtained for CMLC 0.15 S and CMLS 0.05 S respectively. With increase in Co and Sr substitution, XRD and Raman spectra showed that second phases were produced, and densification process of CaMgSi 2 O 6 -based ceramics was promoted. Dielectric constant was influenced by relative density, Raman shift and second phase. The parameter Q×f was affected by the FWHM of Raman peaks as well as extrinsic factors that affected the temperature coefficient of resonant frequency. Therefore, the results suggested the potential of these two ceramics as candidates for LTCC application.