Electronic structure and thermoelectric properties of Na and Ni-doped Ca₃Co₂O₆

Abstract

The electronic structures of Ca₃Co₂O₆, Na and Ni doped models were studied by the quantum chemical software of Cambride 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 substitutional impurity in semiconductors. Na-doped model shows 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.