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Manipulation of ionized impurity scattering for achieving high thermoelectric performance in n-type Mg3Sb2-based materials.

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Title: Manipulation of ionized impurity scattering for achieving high thermoelectric performance in n-type Mg3Sb2-based materials.
Authors: Jun Mao1,2,3, Jing Shuai1,2, Shaowei Song1,2, Yixuan Wu4, Dally, Rebecca5,6, Jiawei Zhou7, Zihang Liu1,2, Jifeng Sun8, Qinyong Zhang9,10, Dela Cruz, Clarina11, Wilson, Stephen5, Yanzhong Pei4, Singh, David J.8, Gang Chen7, Ching-Wu Chu1,2 cwchu@uh.edu, Zhifeng Ren1,2 zren@uh.edu
Source: Proceedings of the National Academy of Sciences of the United States of America. 10/3/2017, Vol. 114 Issue 40, p10548-10553. 6p.
Subjects: Scattering potentials, Carrier proteins, Thermoelectric effects, Thermal conductivity, Ionized gases
Abstract: Achieving higher carrier mobility plays a pivotal role for obtaining potentially high thermoelectric performance. In principle, the carrier mobility is governed by the band structure as well as by the carrier scattering mechanism. Here, we demonstrate that by manipulating the carrier scattering mechanism in n-type Mg3Sb2-based materials, a substantial improvement in carrier mobility, and hence the power factor, can be achieved. In this work, Fe, Co, Hf, and Ta are doped on the Mg site of Mg3.2Sb1.5Bi0.49Te0.01, where the ionized impurity scattering crosses over to mixed ionized impurity and acoustic phonon scattering. A significant improvement in Hall mobility from ~16 to ~81 cm²⋅V-1⋅s-1 is obtained, thus leading to a notably enhanced power factor of ~13 µW⋅cm-1⋅K-2 from ~5 µW⋅cm-1⋅K-2. A simultaneous reduction in thermal conductivity is also achieved. Collectively, a figure of merit (ZT) of ~1.7 is obtained at 773 K in Mg3.1Co0.1Sb1.5Bi0.49Te0.01. The concept of manipulating the carrier scattering mechanism to improve the mobility should also be applicable to other material systems. [ABSTRACT FROM AUTHOR]
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Database: Engineering Source
Description
Abstract:Achieving higher carrier mobility plays a pivotal role for obtaining potentially high thermoelectric performance. In principle, the carrier mobility is governed by the band structure as well as by the carrier scattering mechanism. Here, we demonstrate that by manipulating the carrier scattering mechanism in n-type Mg3Sb2-based materials, a substantial improvement in carrier mobility, and hence the power factor, can be achieved. In this work, Fe, Co, Hf, and Ta are doped on the Mg site of Mg3.2Sb1.5Bi0.49Te0.01, where the ionized impurity scattering crosses over to mixed ionized impurity and acoustic phonon scattering. A significant improvement in Hall mobility from ~16 to ~81 cm²⋅V-1⋅s-1 is obtained, thus leading to a notably enhanced power factor of ~13 µW⋅cm-1⋅K-2 from ~5 µW⋅cm-1⋅K-2. A simultaneous reduction in thermal conductivity is also achieved. Collectively, a figure of merit (ZT) of ~1.7 is obtained at 773 K in Mg3.1Co0.1Sb1.5Bi0.49Te0.01. The concept of manipulating the carrier scattering mechanism to improve the mobility should also be applicable to other material systems. [ABSTRACT FROM AUTHOR]
ISSN:00278424
DOI:10.1073/pnas.1711725114