Investigations of dielectric properties of wolframite A0.5Zr0.5NbO4 ceramics by bond theory and far-infrared spectroscopy.

In this study, intrinsic dielectric properties of monoclinic A 0.5 Zr 0.5 NbO 4 ceramics (A = Mn, Zn, Mg, Co, Ni) with wolframite structure were investigated by chemical bond theory, infrared and terahertz spectroscopy. According to bond theory, Zr–O bonds and A-O bonds with larger bond susceptibility values provide majority contributions to relative permittivity; while Nb–O bonds dominate the structural stability and oxygen polyhedron distortion. Intrinsic dielectric properties calculated via far-infrared reflectivity spectroscopy are close to experimental properties, which indicates that most of dielectric contributions come from absorptions of structural phonon oscillation and infrared modes of dielectric response in A 0.5 Zr 0.5 NbO 4 ceramics vary with A-site ions. Furthermore, intrinsic properties estimated by terahertz time domain spectra also testify the effectiveness of theoretical dielectric properties. [ABSTRACT FROM AUTHOR]