High ZT in p-Type (PbTe)1鈥?x(PbSe)x(PbS)x Thermoelectric Materials

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• 作者：Rachel J. Korkosz ; Thomas C. Chasapis ; Shih-han Lo ; Jeff W. Doak ; Yoon Jun Kim ; Chun-I Wu ; Euripidis Hatzikraniotis ; Timothy P. Hogan ; David N. Seidman ; Chris Wolverton ; Vinayak P. Dravid ; Mercouri G. Kanatzidis
• 刊名：Journal of the American Chemical Society
• 出版年：2014
• 出版时间：February 26, 2014
• 年：2014
• 卷：136
• 期：8
• 页码：3225-3237
• 全文大小：765K
• 年卷期：v.136,no.8(February 26, 2014)
• ISSN：1520-5126

文摘

Lead chalcogenide thermoelectric systems have been shown to reach record high figure of merit values via modification of the band structure to increase the power factor or via nanostructuring to reduce the thermal conductivity. Recently, (PbTe)_1鈥?i>x(PbSe)_x was reported to reach high power factors via a delayed onset of interband crossing. Conversely, the (PbTe)_1鈥?i>x(PbS)_x was reported to achieve low thermal conductivities arising from extensive nanostructuring. Here we report the thermoelectric properties of the pseudoternary 2% Na-doped (PbTe)_1鈥?x(PbSe)_x(PbS)_x system. The (PbTe)_1鈥?x(PbSe)_x(PbS)_x system is an excellent platform to study phase competition between entropically driven atomic mixing (solid solution behavior) and enthalpy-driven phase separation. We observe that the thermoelectric properties of the PbTe鈥揚bSe鈥揚bS 2% Na doped are superior to those of 2% Na-doped PbTe鈥揚bSe and PbTe鈥揚bS, respectively, achieving a ZT 鈮?.0 at 800 K. The material exhibits an increased the power factor by virtue of valence band modification combined with a very reduced lattice thermal conductivity deriving from alloy scattering and point defects. The presence of sulfide ions in the rock-salt structure alters the band structure and creates a plateau in the electrical conductivity and thermopower from 600 to 800 K giving a power factor of 27 渭W/cmK². The very low total thermal conductivity values of 1.1 W/m路K of the x = 0.07 composition is accounted for essentially by phonon scattering from solid solution defects rather than the assistance of endotaxial nanostructures.