Microwave dielectric properties of glass-free CaMg0.9-xLi0.2ZnxSi2O6 ceramics for LTCC applications

Herein, glass-free microwave dielectric ceramics CaMg 0.9-x Li 0.2 Zn x Si 2 O 6 (x = 0–0.36) with excellent microwave dielectric properties were prepared via traditional solid-state reaction method. Phase composition and crystalline structure were identified using X-ray diffraction (XRD), which confirmed that the ceramics contained more than one phase. Rietveld refinement method was utilized to analyze XRD data and obtain structural information, such as lattice parameters. SEM photographs showed that Zn 2+ substitution could effectively promote densification of the ceramics. Microwave dielectric properties were obviously influenced by the combination of multiple phases. Combined with Raman spectra, influences of Raman shift and FWHM of vibration peaks on microwave dielectric properties were determined. The CaMg 0.9-x Li 0.2 Zn x Si 2 O 6 ceramic exhibited high performance at x = 0.28 with: Q  ×  f  = 68,190 GHz, ε r  = 7.51 and τ f  = −68 ppm/°C, when sintered at 900 °C. The studied ceramics are promising candidates for LTCC application.