Modulation of the Microwave Dielectric Properties of Si-Based Olivine Structured Ceramics Through the Variation of A-Site Ions

Abstract

Mg 1+x Co 1−x SiO 4 (x = 0-0.2) microwave dielectric ceramics were prepared via a solid-phase reaction method. X-ray diffraction (XRD) data revealed a single-phase structure for these ceramics, with no phase changes with increasing Mg content, and Mg 1+x Co 1−x SiO 4 (x = 0-0.2) possessed an olivine structure. X-ray diffraction (XRD) patterns were refined via the Rietveld method to obtain crystal structure information. P-V-L bond theory was applied to analyze the crystal structure changes. Scanning electron microscopy (SEM) images highlighted a dense and uniform surface grain distribution with scarce pores. Raman spectroscopy was employed to characterize the impact of lattice vibrations on the Q×f factor. Excellent microwave dielectric properties were exhibited by the MgCoSiO 4 ceramics sintered at 1250 °C for 4 h (ε r = 7.17, Q×f = 46120 GHz, and τ f = −61.7 ppm/°C) and the Mg 1+x Co 1−x SiO 4 (x = 0.05-0.2) ceramics sintered at 1400 °C (ε r = 6.9, Q×f = 118575 GHz, and τ f = −47.7 ppm/°C).Keywords Mg 1+x Co 1−x SiO 4 (x = 0-0.2) ceramics • P-V-L bond theory • Si-based garnet structure