Colossal Dielectric Behavior In Bafeo3-Delta Ceramics

Non-stoichiometric, single-phased barium iron oxide (BaFeO3-delta) has been prepared by solid-state reaction. The low-temperature (5-310 K) dielectric properties of the sample were systematically investigated in terms of X-ray diffraction, scanning electron microscope, X-ray photon spectroscopy, and humidity response measurements. Colossal dielectric behavior similar to that of CaCu3Ti4O12 was found. This behavior was argued to be caused by polaron relaxation due to electrons hopping between Fe3+ and Fe4+ ions. Around room temperature range, the sample shows good humidity response, which leads to surface-layer effect giving rise to a Maxwell-Wagner relaxation. Our results indicate that the sample is a promising humidity sensing material.