Thermodynamic Study on CuInO<sub>2</sub> Preparation by Solid Reaction Method

Abstract

In this paper, the standard entropy, heat capacity at constant pressure, standard enthalpy and standard Gibbs free energy of formation are estimated by application of two-parameter model. The model is relatively simple, accurate and practical. Based on the thermodynamic data for related pure compositions are reported, the five possible chemical reactions in the Cu2O-In2O3 system are studied in the process of preparation CuInO2 by solid reaction method. The relations between equilibrium constant and temperature is plotted. The curves of -T and lgK-1/T for the chemical reactions in the system have also been fitted. The results show that the Cu2O is easy to be oxidized into CuO, which reacts with In2O3 to yield Cu2In2O5 at lower temperature. However, the CuInO2, which is prepared from the Cu2O-In2O3 system, is oxidized into Cu2In2O5 easily in the oxygen atmosphere. The reaction of preparing CIO was reversible and incomplete. Therefore, preparation CIO is very difficult by solid reaction method whether in atmospheric pressure or isolated air and gas shield conditions, because K1 >-40kJ/mol.