Dielectric properties and impedance characteristics of BaO–Cr2O3–Sb2O5 ceramics

A series of polycrystalline BaO–Cr2O3–Sb2O5 (BCS) ceramics were fabricated by the conventional solid-state reaction method. The phase composition, microstructures, sintering characteristics and dielectric properties were systematically investigated. The results showed that major phases were indexed to be hexagonal BaSb2O6 and orthorhombic BaCr2O4, and microstructures were markedly influenced by sintering temperatures. Dielectric study in a wide temperature (20–300 °C) and frequency (100–10 MHz) range has been performed. With increasing temperature, the real (ε′\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\varepsilon^{\prime }$$\end{document}) and imaginary (ε″\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\varepsilon^{\prime \prime }$$\end{document}) parts of dielectric permittivity similarly enhanced at low frequencies, indicating a thermally activated relaxation. Complex impedance spectroscopy analysis reveals that the dielectric behavior is attributed to the huge interfacial polarization and electrical response of grain boundaries. The activation energy for relaxation (0.486 eV) is nearly comparable to that for the dc conduction process (0.502 eV), implying the polarization process depends on polaron hopping based on electron carriers.