ICT2014 Abstracts

Thermoelectric materials are capable of interconverting heat and electricity directly. The high thermoelectric performance of β-Zn₄Sb₃ has drawn much attention for its application in the intermediate temperature range. In this work Zn₄Sb₃In_δ (0≤δ≤0.08) thermoelectric compounds were prepared by a melt-quenching and spark plasma sintering method, and the properties were studied by X-ray diffraction, X-ray photoelectron spectroscopy, differential scanning calorimetry and physical property measurements. The indium atom acts as dopant and occupies the interstitial site in the crystal lattice of β-Zn₄Sb₃. The electrical conductivity decreases and then increases with increasing the δ in the range of 0~0.06 for Zn₄Sb₃In_δ compounds, however the Seebeck coefficients are nearly the same. All the In-doped Zn₄Sb₃In_δ compounds show smaller thermal conductivity compared with the pure β-Zn₄Sb₃ one, which results from the decreased lattice thermal conductivity due to the enhanced phonon scattering by indium doping. The dimensionless figure of merit, ZT, for the In-doped Zn₄Sb₃In_δ compounds is greater than that of the pure β-Zn₄Sb₃ in the temperature range investigated. In particular, the ZT of the Zn₄Sb₃In_δ (δ=0.06) compound reaches a maximum value of 1.01 at 700 K, which is 22% greater than that of the pure β-Zn₄Sb₃ obtained in this study. The increase in power factor for the Zn₄Sb₃In_δ compounds is related to the doping behavior and the change of valence state of indium atom.