Sol–gel processing of In-doped CaZrO3 solid electrolyte and the impedimetric sensing characteristics of humidity and hydrogen

Ten mole percent In-doped CaZrO3 and CaZrO3 perovskite solid electrolytes were prepared by a sol–gel method (SGM). The phase evolution of the synthesized precursor powders under thermal treatments was investigated by differential thermal analysis (DTA) and X-ray diffraction (XRD). The green bodies (pellets) were formed by uniaxial pressing of calcined SGM powders. The pellets were sintered at different temperatures and used for possible high-temperature humidity sensor application. The electrical response of the sensors to humidity and hydrogen was investigated at relatively high temperatures (e.g. 700 °C) using impedance analysis. The influence of oxygen partial pressure on the electrical response of the humidity and hydrogen sensor and the relation between oxygen ion conduction and protonic conduction of the In-doped CaZrO3 are briefly discussed.