Effects of calcining temperature on the phase structure and the formaldehyde gas sensing properties of CdO-mixed In2O3

The CdO-mixed In2O3 materials with a molar ratio of 1:1 calcined at different temperatures were prepared using the solid-state synthesis technologies. The effect of the different calcining temperatures on the phase structures of CdO-mixed In2O3 was investigated by powder X-ray diffraction. Indirect-heating sensors using CdO-mixed In2O3 calcined at different temperatures as sensitive materials were fabricated on an alumina tube with Au electrodes and Platinum wires. Gas-sensing characteristics of CdO-mixed In2O3 to formaldehyde were investigated. It is found that CdIn2O4 came into be formed from CdO-mixed In2O3 more than 700 °C. The results show that the phase structure, the electronic and the gas sensing properties to formaldehyde were changed with the different calcining temperatures. The CdO-mixed In2O3 based gas sensors exhibit highest response to formaldehyde after calcining at 650 °C, making them to be promising candidates for practical detectors for formaldehyde.