Crystal structure, Raman spectra, bond characteristics, and microwave dielectric properties of MnMoO4 ceramics

MnMoO4 ceramic was prepared using solid-state reaction method. XRD and Rietveld refinement results confirmed the formation of a single phase of MnMoO4 with monoclinic structure of C2/m space group. Excellent microwave dielectric properties, including εr = 9.32, Q × f = 56,230 GHz, and τf = −62.32 ppm/°C, were achieved for the resulting MnMoO4 ceramic at 925 °C, which had a relative density of 97%. The dielectric polarization and packing fraction were closely related to the dielectric constant and quality factor of MnMoO4 ceramics, respectively. Furthermore, our P–V-L analysis demonstrated that the ionicity, lattice energy, and bond energy of chemical bonds were all dominated by the Mo–O bond, which had a greater influence on microwave dielectric properties than the Mn–O bond. This finding was confirmed using Raman spectroscopy, which revealed that [MoO4] tetrahedron vibrations predominated Raman vibrations, supporting the P–V-L theory. Additionally, the chemical compatibility of the MnMoO4 ceramic with Ag co-firing was explored to investigate potential technological applications.