Atmospheric effect for thermal process of indium hydroxoformate

Abstract

The influence of thermal process for indium hydroxoformate, In(OH)(HCO2)2, used as one of the precursor material of ITO transparent conducting films, has been successfully investigated in some controlled atmospheres by unique thermal analyses equipped with a humidity generator, which are thermogravimetry - differential thermal analysis (TG-DTA), thermogravimetry in conjunction with evolved gas analysis using mass spectrometry (TG-MS) and simultaneous measurement of differential scanning calorimetry and X-ray diffractometry (XRD-DSC). The thermal process in dry gas atmosphere by linear heating experiment was indicated through a single-step reaction between 200 and 300°C, while the thermal process in the atmosphere of controlled humidity proceeded through two-step reactions and the formation of crystalline indium oxide (In2O3) was effectively promoted and completed at the lower temperatures with introducing water vapor in the atmosphere. The thermal process changed dramatically by introducing water vapor and was quite different from that in dry gas atmosphere. Pure In2O3 was synthesized in inert atmosphere of controlled humidity and could be easily formed at temperatures below 260°C. The XRD-DSC equipped with a humidity generator revealed directly the crystalline change from In(OH)(HCO2)2 to In2O3 and the formation of the intermediate during the thermal decomposition. A detailed thermal process of In(OH)(HCO2)2 and the effect of heating atmosphere are discussed.