Study of the humidity effect in the electrical response of the KSbMoO6 ionic conductive ceramic at low temperature

The effect of sorbed water vapor on the electrical response of a ceramic, metallic complex oxide (KSbMoO6) with characteristics of ionic conductor has been studied by means of several experimental techniques aiming to explore its application as a humidity sensor. Electrical behavior was studied employing impedance spectroscopy, thermoelectric analysis and charging current analysis, showing that the incorporation of water actually determines the main electrical features of the system. It has been observed that water is present in the: system in two basic forms: loosely associated on the sample surface and tightly bound inside the ceramics. Impedance measurements performed under atmospheres of different relative humidity allow to differentiate between such kinds of sorbed water. We propose that the dissociation of water molecules generates mobile protons responsible of the observed impedance patterns. In addition, we conclude that the design of humidity sensors based on materials of ceramic structure should count on a proper understanding of the underlying ionic transport mechanisms. (C) 2002 Published by Elsevier Science B.V.