Thermogravimetric analysis and hot-stage Raman spectroscopy of cubic indium hydroxide

Abstract

The transition of cubic indium hydroxide to cubic indium oxide has been studied by thermogravimetric analysis complimented with hot-stage Raman spectroscopy. Thermal analysis shows the transition of In(OH)3 to In2O3 occurs at 219 °C. The structure and morphology of In(OH)3 synthesised using a soft chemical route at low temperatures was confirmed by X-ray diffraction and scanning electron microscopy. A topotactical relationship exists between the micro/nano-cubes of In(OH)3 and In2O3. The Raman spectrum of In(OH)3 is characterised by an intense sharp band at 309 cm−1 attributed to ν1 In–O symmetric stretching mode, bands at 1137 and 1155 cm−1 attributed to In-OH δ deformation modes, bands at 3083, 3215, 3123 and 3262 cm−1 assigned to the OH stretching vibrations. Upon thermal treatment of In(OH)3, new Raman bands are observed at 125, 295, 488 and 615 cm−1 attributed to In2O3. Changes in the structure of In(OH)3 with thermal treatment is readily followed by hot-stage Raman spectroscopy.