铁酸系列复合金属氧化物铝热反应焓的理论研究

运用密度泛函理论(DFT),在Material Studio程序包的GGA-PBE、GGA-BLYP、GGA-PW91泛函结合DNP基组水平上,计算了7种常见金属氧化物的铝热反应焓。将计算值与实验值进行对比,确定出最佳计算基组水平。在此基础上,对6种铁酸系列复合金属氧化物(CuFe2O4、NiFe2O4、CoFe2O4、MgFe2O4、ZnFe2O4、MnFe2O4)的铝热反应焓进行了理论计算,并运用盖斯定律导出其标准摩尔生成焓。结果表明,GGA-PBE/DNP方法计算的标准摩尔反应焓精度高、误差小,平均误差7.072kJ/mol;在GGA-PBE/DNP水平下,6种复合金属氧化物的铝热反应焓分别为-3 695.02、-3 388.53、-3 380.13、-841.06、-3 142.57和-2 738.40kJ/mol,与等量物理混合金属氧化物的铝热反应焓相差不大。6种复合金属氧化物标准摩尔生成焓为-992.96、-1 092.12、-1 090.13、-1 431.13、-1 185.15和-1 311.78kJ/mol。

Theoretical Study of Thermite Reaction Enthalpy for Metal Composite Oxides of Ferrite Series

By using the density functional theory (DFT), the thermite reaction enthalpies of 7 kinds of common metal oxides were calculated with GGA-PBE, GGA-BLYP, GGA-PW91 functional in conjuction with DNP basis set in the Material Studio package. The calculated values were compared with the experimental ones to determine the optimum calculation basis set level. On this basis, the thermite reaction enthalpies of six kinds of metal composite oxides of ferrite series (CuFe2O4, NiFe2O4, CoFe2O4, MgFe2O4, ZnFe2O4 and MnFe2O4) were theoretically calculated, and Hess′s law was employed to calculate their standard molar enthalpies of formation. The results show that the claclulation method based on the GGA-PBE functional in conjuction with DNP basis set is most precise, and the mean error (ME) of common thermite reactions between calculated and experimental enthalpies is 7.072kJ/mol. At GGA-PBE/DNP level, thermite reaction enthalpies of the six compounds are -3695.02,-3388.53, -3380.13,-841.06, -3142.57 and -2738.40 kJ/mol, respectively,which is little different with that of the equivalent physical mixed metal oxides. The standard molar enthalpies of formation of six substances are -992.62, -1092.12, -1090.13, -1431.13, -1185.15 and -1311.78 kJ/mol, respectively.