Electronic Structure and Thermoelectric Properties of Na and Ni-doped Ca_3Co_2O_6

摘要

The electronic structures of Ca_3Co_2O_6, Na and Ni doped models were studied by the quantum chemical software of Camhride Serial Total Energy Package (CASTEP) that is based, on density function theory (DFT) and pseudo-potential. The electronic conductivity, seebeck coefficient, thermal conductivity and figure of merit ( Z) were computed. The energy band structure reveals the form of the impurity levels due to the substitu-tional impurity in semiconductors. Na-doped model shoivs the character of p-type semiconductor, but Ni-doped model is n-type semiconductor. The calculation results show that the electric conductivity of the doped model is higher than that of the non- doped model, while the Seebeck coefficient and thermal conductivity of the doped model are lower than those of the non-doped one. Because of the great increase of the, electric conductivity, Z of Na-doped model is enhanced and thermoelectric properties are improved. On the other hand, as the large decline of Seebeck coefficient, Z of Ni- doped model is less than that of the non- doped model.