Effect of Al substitution on Thermoelectric Performance of CuInTe 2 compounds
- PDF / 33,213,022 Bytes
- 9 Pages / 612 x 792 pts (letter) Page_size
- 83 Downloads / 138 Views
Effect of Al substitution on Thermoelectric Performance of CuInTe2 compounds Chuandeng Hu1, Kunling Peng1,2, Guiwen Wang1,2,Lijie Guo1, Guoyu Wang*2, Xiaoyuan Zhou*1 1
College of Physics, Chongqing University, Chongqing 401331, P. R. China. Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Sciences, Chongqing 400714, P. R. China. 2
Corresponding author: Tel: +86-23-6593-5603; Fax: +86-23-6567-8362 Email: [email protected]; [email protected] ABSTRACT Thermoelectric CuIn1-xAlxTe2 compounds (x=0, 0.05, 0.1, 0.15, 0.50) have been synthesized by solid state reaction followed by spark plasma sintering. The influence of Al substitution on electrical and thermal transport properties has been investigated in the CuInTe2 compounds. It was found that the Seebeck coefficient and electrical conductivity is reduced by isovalent replacement of In with Al. Our first principle calculation indicates Al substitution leads to the widen band gap, the reduction in the number of degeneracy of valence band and the effective mass. Furthermore, a large reduction in thermal conductivity is achieved through the enhanced phonon scattering via point defect as well as the nano-sized particles observed between grain boundaries and on the grain surface. In spite of the reduced charge transport properties, an improved figure-of- merit ZT is achieved, reaching 0.8 at 800 K, 33% higher in comparison to the pure CuInTe2 compound.
INTRODUCTION The world we are living in has been stressed by the rapidly growing energy consumption and associated with it environmental problems. To solve these problems, or at least mitigate their influence, the new green energy policies and the more efficient ways we use the energy, should be considered. Thermoelectric (TE) materials are a very good candidate to achieve a more efficient usage of energy, especially in the area of waste industrial heat [1-4]. The figure of merit, ZT, defined as ZT=S2σT/κ, where S is the Seebeck coefficient, σ is the electrical conductivity, κ is the thermal conductivity, and T is the absolute temperature, is the parameter which describes the performance of the TE material. The electronic performance of a thermoelectric material is governed by its power factor P=S2σ. The challenge to develop efficient TE materials is to achieve a simultaneous enhancement in the power factor while maintaining as low thermal conductivity as possible. Recently, a class of I-III-VI2 (I = Cu, Ag; III = Al, Ga, In; VI = S, Se, Te) compounds with diamond-like structure and wide band gap has been found to have reasonable thermoelectric performance [5-14]. Similar to ternary Cu2MSe3, the structure of this compound can also be derived from cubic zinc-blende structure. Zn layer in ZnTe structure are cross-substituted by ordered Cu-In atoms, leading to a tetragonal (chalcopyrite) structure with the space group I42dVI [5, 14]. Even though it has a relatively low electrical conductivity compared with those of
traditional small band gap thermoelectrics, the lattice thermal conductivity o
