The effect of humidity on the conductivity processes in polycrystalline Cu2+-stabilised K+-β″-ferrite

The effect of humidity on the conductivity of Cu2+-stabilised K+-β″-ferrite was investigated by impedance spectroscopy. Several conductivity processes could be determined in the temperature range between 20 and 500°C in humidified atmospheres with water partial pressures between 26 and 2510 Pa. Bulk conductivity, conductivity through grain boundaries and electrode processes were found for as-prepared samples. In aged samples an additional conductivity at the grains surfaces was revealed. Thermogravimetric analysis was used to explain this behaviour. A non-uniform and time dependent water distribution profile along the diameter of pressed polycrystalline samples is suggested.