Ti-O体系化合物的生成吉布斯自由能的计算与分析

Calculation and Analysis of the Standard Gibbs Free Energy of Formation for Ti-O Compounds

应用氧势递增原理对Ti-O体系中24种化合物的标准生成吉布斯自由能ΔfG°进行了计算分析.结果显示,1304K时Ti26O51与Ti28O55平衡的氧势和Ti24O47与Ti26O51平衡的氧势违背了氧势递增原理,表明Ti24O47,Ti26O51和Ti28O55三种物质的ΔfG°数据中至少一个有误.在详细介绍用氧势递增原理和拟抛物线规则估算ΔfG°方法的基础上,分别对这3种氧化物的ΔfG°进行了估算,两种方法的计算结果一致,1304K时ΔfG°Ti24O47=-16785.366±0.011kJ/mol,ΔfG°Ti26O51=-18202.261±0.021kJ/mol,ΔfG°Ti284O55=-19619.080±0.008kJ/mol.对估算结果分析认为,原Ti26O51的ΔfG°有误的可能性最大.依据评估后的数据,以碳热还原和氢气还原TiO2制备了Ti4O7.

The rule of oxygen potential increasing with oxygen mole fraction in oxides and calculation with computer are applied to assess the data of standard Gibbs free energy of formation △fG0 for 24 types of Ti-O compounds obtained from literatures. The results show that the relationship of oxygen potential with the equilibrium reactions of Ti26O51 with Ti28055 and Ti24O47 with Ti26051 do not obey the rule of oxygen potential increasing at 1304 K. It is suspected that one of △fG0 data of Ti24047, Ti26O51, and Ti28O55 is error. The methods of evaluating △fG0 by both the oxygen potential increasing and quasi-parabola rules are explained in detail. Then △fG0 data of Ti24O47, Ti26O51, and Ti28055 are separately evaluated. The results obtained by the two different methods are the same. At 1304 K they are △fG0Ti24O47=-16785.366±0.011 kJ/mol, △fG0Ii26O51=-18202.261±0.021 kJ/mol, △fG0Ti284O55=-19619.080±0.008 kJ/mol. These results are analyzed, which shows that the original value in △fG0 of Ti26051 is probably larger error. Based on the assessed data, Ti4O7 material is prepared from TiO2 by carbothermal and hydrogen reduction methods.