Two kinds of
indium-tin oxide (ITO) precursors, cubic indium hydroxide (In(OH)3) and orthorhombic indium oxide hydroxide
(InOOH), were prepared by a co-precipitation method. With the help of X-ray diffraction (XRD), thermo-gravimetric analysis (TGA) and differential thermal analysis (DTA), phase evolutions from cubic In(OH)3 and orthorhom-bic InOOH to cubic ITO solid solution and rhombohedral ITO solid solution by heat-treatment had been comprehensively investigated. The
transformation from cubic In(OH)3 to cubic ITO solid solution started as low as 150°C and ended at about 300°C, and it exhibited an endothermic behavior. The transformation from orthorhombic InOOH to rhombohedral ITO solid solution started at 220°C and ended at about 430°C. Moreover, this transformation was composed of two processes: the one was the dehydration of InOOH exhibiting an endothermic behavior and the other was the transformation from de-hydration products to rhombohedral ITO solid solution exhibiting a strong exothermic behavior. Rhombohedral ITO solid solution was metastable in air and it would transform to cubic ITO solid solution by heat-treatment. The transformation from rhombohedral ITO solid solution to cubic ITO solid solution started at 578°C and ended below 800°C, and it exhibited a weak exothermic behavior.