Glass-free CaMg0.9−xLi0.2MnxSi2O6 ceramics with enhanced dielectric properties for microwave and THz frequency applications

Abstract

Glass-free CaMg0.9−xLi0.2MnxSi2O6 ceramics with outstanding microwave dielectric properties were systematically investigated. Rietveld refinement and Raman spectroscopy were utilized to analyze X-ray diffraction patterns and understand the effect of the Mn2+ incorporation on structure and dielectric properties. Refined data revealed the change in each phase. For x = 0.06, the content of second phase was the lowest. Scanning electron microscopy showed that after Mn2+ incorporation, the average grain size increased. Factors affecting the relative density, dielectric constant, Q×f value, and temperature stability coefficient were discussed. Notably, CaMg0.84Li0.2Mn0.06Si2O6 ceramics sintered at 925 °C for 3 h acquired excellent microwave dielectric properties: εr = 7.799, Q×f = 36207 GHz, and τf = −35.58 ppm/°C. Additionally, ceramics exhibited low dielectric constant (εr = 5.45) and dissipation factor (tanδε = 0.055) in THz range. Thus, these ceramics are suitable for application in the THz range.