Crystal structure, infrared spectra, and microwave dielectric properties of the EuNbO4 ceramic

Abstract The novel microwave dielectric ceramic EuNbO4 with monoclinic structure (PDF # 22-1099) was synthesized using the conventional solid-state reaction process. X-ray diffraction and Rietveld refinement were employed to investigate the phase compositions and crystal parameters. Combined with the refinement results, the structure-property relationship was analyzed using the chemical bonds theory of complex crystals. The surface microtopography was characterized using scanning electric microscope, and the dense and homogeneous microstructures could be observed at EuNbO4 ceramic sintered at 1125 °C. Infrared reflectivity spectra indicated the absorption of structural phonon oscillation might be the main contribution to polarization for EuNbO4 ceramic. The optimal dielectric properties with er = 19.1, Q × f = 15,014 GHz, and τf = −16.42 ppm/°C were achieved in EuNbO4 ceramic sintered at 1125 °C.