Enhanced thermoelectric performance via the solid solution formation: The case of pseudobinary alloy (Cu2Te)(Ga2Te3)3 upon Sb substitution for Cu

Publication date: 5 February 2017
Source:Materials & Design, Volume 115
Author(s): Jiaolin Cui, Xianglian Liu, Zhengliang Du, Yimin Chao
In this work we have observed the beneficial effect from the solid solution formation on the thermoelectric performance of (Cu2(1−x)Sb2xTe)(Ga2Te3)3 upon Sb substitution for Cu. This substitution allows the different occupations of Sb in the crystal lattice, i.e. Sb at Cu sites with x≤0.05 and at Ga sides with x≥0.05, which has resulted in the Pisarenko relation does not exactly capture the measured Seebeck coefficient under assumed effective masses m*. The reduction of the lattice thermal conductivity (κL) has been quantified within the temperature range from room temperature to 723K. Over the entire composition range, the κL value is reduced by 33% and 25% at temperature 723K and 580K, respectively. This observation is in a good agreement with the theoretical calculation based on the Callaway model used in the solid solutions. Along with the increasing of the mobility and electrical conductivity, the thermoelectric performance has been improved with the highest ZT value of 0.58 at 723K, which is about double the value of intrinsic (Cu2Te)(Ga2Te3)3.

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