Structure, infrared spectrum, and microwave dielectric properties of NiO–TiO2–Nb2O5 ceramics

This study reports the crystal structure and intrinsic dielectric properties of NiO–TiO2–Nb2O5 ceramics. The NiO–TiO2–Nb2O5 system is crystallized as a rutile structure based on X-ray diffraction, Rietveld refinement, and TEM analysis. The sintering temperature has a certain positive effect on the dielectric constant and Q × f value, which is attributed to the reduction of porosity and the growth of crystals. Because of the particularity of the rutile structure, ionic polarizability cannot be used to evaluate the micro-polarization mechanism. Thus, using the far-infrared reflectance spectrum and complex dielectric function analysis, the high-frequency micro-polarization mechanism of the structure has been fully explained, which is expected to be applied to other high-εr dielectric ceramic systems.