Study On Preparation Of Ultrafine In₂O₃Powders

Indium tin oxide (ITO) thin films are widely used in flat panel displays, solar cells and other fields due to their excellent optical and electrical properties. In2O3powder is one of the main raw materials for the preparation of ITO films and its preparation method is widely concerned for a long time.In this paper, the study on the preparation of ultrafine In2O3powders using hydrolysis precipitation-hydrothermal treatment-calcination method was carried out. The effects of temperature, pH value and time on the morphologies, sizes and crystal forms of the products were investigated by means of SEM, XRD, BET and Laser particle size analyser.The results showed that the hydrolysis precipitate product was mianly cubic crystal In(OH)3with a morphology of short rod-like aggregates, the long and short axises of which were about1μm and0.2-0.3μm, respectively. Hydrothermal treatment for the hydrolysis precipitate In(OH)3had significant effects on its morphology, particle size and crystal structure. In the hydrothermal process, morphology and structure of the product were affected through both mechanisms of Ostwald ripening and phase transition. At hydrothermal temperature less than280℃, the morphology of the particles transfers from short rods to cuboids through Ostwald ripening mechanism; while at hydrothermal temperature higher than280℃, the processes of Ostwald ripening and phase transition take place successively:firstly, the morphology of the particles changes from short rods to cuboids through Ostwald ripening, and then, the phase transition from cubic In(OH)3to rhombohedral InOOH occurs, changing the morphology of the particles from cuboids to polyhedron. In2O3powders could be obtained by the calcination of various precursors at500℃for2h, and the morphologies of calcination products inherite their precursors.Ultrafine In2O3powders of uniform crystal form, spherical morphology, and controlled particle size could be prepared by the hydrolysis precipitation-hydrothermal treatment-calcination method. The results obtained in this study could provide guidance for the preparations of high quality In2O3powders, as well as other metal oxide powder materials.