Improvement in the Thermoelectric Figure of Merit by La/Ag Cosubstitution in PbTe

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• 作者：Kyunghan Ahn^† ; ; Changpeng Li^‡ ; ; Ctirad Uher^‡ ; ; Mercouri G. Kanatzidis*^† ;
• 刊名：Chemistry of Materials
• 出版年：2009
• 出版时间：April 14, 2009
• 年：2009
• 卷：21
• 期：7
• 页码：1361-1367
• 全文大小：234K
• 年卷期：v.21,no.7(April 14, 2009)
• ISSN：1520-5002

文摘

The thermoelectric properties of La-doped and Ag/La codoped PbTe were investigated in the temperature range of 300 to 720 K. All samples crystallize in the NaCl-type structure without noticeable secondary phase and exhibit narrow bandgaps of 0.26−0.30 eV, typical of PbTe. La doping (≤5 at %) in PbTe significantly enhances the room temperature electrical conductivity to >5000 S/cm, indicating that La is an efficient electron donor. Hall coefficient data confirm the significant increase in electron carrier concentration from 2 × 10¹⁸ cm⁻³ at 300 K for PbTe to 5.3 × 10¹⁹ cm⁻³ for Pb_0.99La_0.01Te, and 1.7 × 10²⁰ cm⁻³ for Pb_0.95La_0.05Te. Ag doping in Pb_0.99La_0.01Te has an opposite effect on the electron carrier concentration (2.0 × 10¹⁹ cm⁻³ at 300 K for Ag_0.05Pb_0.99La_0.01Te and 1.5 × 10¹⁹ cm⁻³ for Ag_0.1Pb_0.99La_0.01Te), consistent with the role of Ag as electron acceptor. The temperature dependence of mobility is discussed in detail using the physics of electron scattering and possible scattering mechanisms. For Ag_0.05Pb_0.99La_0.01Te, a high power factor of 22 μW/(cm K²) at 720 K was achieved with the optimal total thermal conductivity of 1.3 W/(m K) at 720 K, giving a maximum figure of merit ZT ≈ 1.2 at 720 K.