Thermodynamics of CuInO2Preparation by Cation Exchange Reaction

Abstract

Abstract To investigate the optimum conditions of the CuInO2 (CIO) preparation by cation exchange reaction method, the standard entropy, thermal capacity at constant pressure, standard enthalpy and standard Gibbs free energy of formation were estimated. The relations of temperature (T) and thermodynamic equilibrium constants (K), the conditions for three independent reactions were analyzed in CuInO2 preparation. The curves of Gibbs free energy-T, K − T and PCuCl − T for those reactions have been plotted. The results showed that the CIO powder could be synthesized by cation exchange reaction. There were two main reactions through the way of NaInO2 reacting with CuCl. One was NaInO2(s) reacting with CuCl(s) at T ≥ 1698 K. The cost was higher in the way. The other was NaInO2(s) reacting with CuCl(g) at T < 1698 K. However, the yield of CIO would be decreased because CuInO2 powder decomposed into Cu2O(s) and In2O3(s) with the temperature reduced, especially when T ≤ 573 K. And the higher vapor pressure of CuCl(g) was necessary for the process, which needs the higher temperature since the vapor pressure of CuCl(g) increases with increasing temperature, especially when T > 973 K. It was recommended that NaInO2(s) react with CuCl(g) for preparing CIO under conditions of 973 < T ≤ 1698 K and the vacuum in the reactor.