Recent progress of half-Heusler for moderate temperature thermoelectric applications
Shuo Chen* and Zhifeng Ren
Department of Physics and Texas Center for Superconductivity, University of Houston, Houston, TX 77204, USA
Half-Heusler thermoelectric materials have been attracting extensive research interest over the last two decades. In this mini-review article, we summarize the synthesis methods for optimizing individual parameters to enhance the thermoelectric performance in both MNiSn (n-type) and MCoSb (p-type) based half-Heuslers. Some more recently available approaches, such as using metallic phase nanoinclusions as dopants to enhance electrical conductivity and lowenergy carrier filtering to enhance Seebeck coefficient, resonant states near Fermi level for a higher Seebeck coefficient, and nanosized grains formed by rapid hot pressing to reduce thermal conductivity, are discussed in this article. In addition, the effect of high temperature annealing is also discussed, which is important for device performance.

A review on thermoelectric renewable energy: Principle parameters that affect their performance
Developing thermoelectric materials with superior performance means tailoring interrelated thermo-electric physical parameters – electrical conductivities, Seebeck coefficients, and thermal conductivities –for a crystalline system. High electrical conductivity, low thermal conductivity, and a high Seebeck coefficient are desirable for thermoelectric materials. Therefore, knowledge of the relation between electrical conductivity and thermal conductivity is essential to improve thermoelectric properties. In general, research in recent years has focused on developing thermoelectric structures and materials of high efficiency. The importance of this parameter is universally recognized; it is an established, ubiquitous, routinely used tool for material, device, equipment and process characterization both in the thermoelectric industry and in research. In this paper, basic knowledge of thermoelectric materials and an overview of parameters that affect the figure of merit ZT are provided. The prospects for the optimization of thermoelectric materials and their applications are also discussed.
Contents
1. Introduction
2. Thermoelectric properties
2.1. The Seebeck coefficient
2.2. Thermal conductivity
2.3. Electrical resistivity (ρ)
3. Categories of TE material
3.1. Metal-based thermoelectrics
3.2. Ceramics
3.3. Polymers
3.4. Semiconductors
4. Governing parameters for thermoelectric material selection: intrinsic material properties
4.1. Energy gap and band structure in semiconductors
4.2. Charge carrier concentration.
4.3. Mobility
5. Auxiliary properties
5.1. Diffusion properties
5.2. Oxidizability
5.3. Brittleness
5.4. Compression and shear strength
5.5. Coefficient of thermal expansion (CTE)[ Last edited by 穿越千年 on 2013-11-21 at 21:10 ]

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