Title

The effects of Te2− and I− substitutions on the electronic structures, thermoelectric performance, and hardness in melt-quenched highly dense Cu2-xSe

RIS ID

98118

Publication Details

Zhao, L., Wang, X., Yun, F. F., Wang, J., Cheng, Z., Dou, S., Wang, J. & Snyder, G. (2015). The effects of Te2− and I substitutions on the electronic structures, thermoelectric performance, and hardness in melt-quenched highly dense Cu2-xSe. Advanced Electronic Materials, 1 (3), 1400015-1-1400015-8.

Abstract

A systematic study has been carried out on the electronic band structure and density of states, crystal structures, thermoelectric properties, and hardness of the Cu2-xSe system with and without Te2− or I substitutions for Se2−. Density functional theory calculations indicate that stoichiometric Cu2Se is a zero-gap material, and copper-deficient Cu1.875Se is a p-type conductor. Te2- substitution increases the total density of states at the Fermi level, whereas, the I substitution leads to the reduction of the total and partial density of states for both Se and Cu. Highly dense undoped, Te-doped, and I-doped Cu2-xSe bulks have been fabricated by a melt-quenching method which only takes a few minutes. Rietveld refinements of the X-ray diffraction patterns reveal that the unit cells are expanded after doping. All the fabricated bulks are p-type conductors in accordance with band structure calculations, and they all have figure of merit, zT, values over or close to 1.0 at T = 973 K, except for the Cu2-xTe0.16Se0.84. Furthermore, the hardness is distinctly improved by the doping approach, with a maximum value of ca. 0.66 GPa for the Cu2-xTe0.16Se0.84, which is higher than those of polycrystalline Bi2Te3 and PbTe bulks.

Grant Number

ARC/DP130102956, ARC/FT130100778, ARC/LE120100069

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Link to publisher version (DOI)

http://dx.doi.org/10.1002/aelm.201400015