Simple estimation method for thermodynamic data of complex oxysalt minerals

A simple estimation method for molar Gibbs free energy and enthalpy of formation for complex oxysalt minerals is proposed. Complex oxysalt minerals are divided into complex oxysalt minerals with water and complex oxysalt minerals without water. Complex oxysalt minerals without water can be considered as the composite of acidic oxides and alkaline oxides, so their molar Gibbs free energy or molar enthalpy of formation can be calculated by the summation of molar Gibbs free energy or molar enthalpy of formation of the acidic oxides and alkaline oxides which are combined into the complex compounds. Molar Gibbs free energy or molar enthalpy of formation of complex oxysalt minerals with water is obtained by the summation of molar Gibbs free energy or molar enthalpy of formation of the part without water and water. The calculation method represented in this paper is very simple and convenient. By comparing the relative errors, the method is better than other methods. Moreover, it can be used to calculate molar Gibbs free energy and molar enthalpy of formation of all complex oxysalt minerals including a series of titanate whiskers that author's group has studied for many years. The thermodynamic data for the series of titanate whiskers provide necessary fundamentals to their preparation.