The Quantum Chemistry Calculation and Thermoelectrics of Bi-Sb-Te Series

摘要

The density function theory and discrete variation method (DFT - DVM) was used to study correlation between composition, structure, chemical bond, and property of thermoelectrics of Bi-Sb- Te series. 8 models of Bi_(20-x)Sb_xTe_(32)(x=0,2,6,8,12,14,18 and 20) were calculated. The results shots that there is less difference in the ionic bonds between Te(I)-Bi(Sb) and Te(II)-Bi(Sb), but the covalent bond of Te(I) Bi(Sb) is stronger than that of Te(II)-Bi(Sb). The interaction between Te(I) and Te(I) in different layers is the weakest and the interaction should be Van Der Waals power. Tie charge of Sb is lower than that of Bi, and the ionic bond of Te-Sb is weaker than that of Te-Bi. The covalent bond of Te - Sb is also weaker than that of Te-Bi. Therefore, the thermoelectric property may be improved by adjusting the electrical conductivity and thermal conductivity through changing the composition in the compounds of Bi- Sb-Te. The calculated results are consistent with the experiments.