Developing thermoelectric materials with superior performance means tailoring interrelated thermoelectric 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.

A review on thermoelectric renewable energy: Principle parameters that affect their performance

Recent advances in thermoelectric materials

Recent progress of half-Heusler for moderate temperature thermoelectric applications

Thermoelectric (TE) materials facilitate direct heat-to-electricity conversion. The performance of a TE material is characterised by its figure of merit zT (=S2 σT/κ) that depends on both electronic transport properties, i.e. the Seebeck coefficient S and the electrical conductivity σ, and on thermal transport properties, i.e. the thermal conductivity κ of a material. The intrinsically counter-correlated behaviour between electronic and thermal transport properties makes the enhancement of zT a very challenging task. In the past 10 years, the zTs in bulk TE materials have been significantly enhanced due to intensive exploratory efforts, the discovery of new physical phenomena and effects, and applications of advanced synthesis methods. In this review, we summarise the recent progress in bulk TE materials. After the introduction of fundamental principles of thermoelectricity, the recently achieved enhancements in the TE performance encompassing the use of electronic band structure engineering, lattice phon...

Recent advances in high-performance bulk thermoelectric materials

Half-Heusler compounds are an impressive class of materials with a huge potential for different applications such as future energy applications and for spintronics. The semiconducting Heusler compounds can be identified by the number of valence electrons. The band gap can be tuned between 0 and 4 eV by the electronegativity difference of the constituents. Magnetism can be introduced in these compounds by using rare-earth elements, manganese or ‘electron’ doping. Thus, there is a great interest in the fields of thermoelectrics, solar cells and diluted magnetic semiconductors. The combination of different properties such as superconductivity and topological edge states leads to new multifunctional materials, which have the potential to revolutionize technological applications. Here, we review the structure, the origin of the band gap and the functionalities of semiconducting half-Heusler compounds.

https://iopscience.iop.org/article/10.1088/0268-1242/27/6/063001/pdf

Half-Heusler compounds: Novel materials for energy and spintronic applications

Thermoelectric properties of the TiX(Zr0.5Hf0.5)1 − XNiSn half-Heusler compounds

Disclosed is a thermoelectric module, comprising a plurality of p-type thermoelectric elements each comprising a p-type semiconductor having a skutterdite crystal structure, a plurality of n-type thermoelectric elements each comprising a n-type semiconductor having a skutterdite crystal structure, at least one first electrode, at least one second electrode, at least one first alloy layer and at least one second alloy layer, wherein said at least one first alloy layer and said at least one second alloy layer contain Sb and at least one transition metal element selected from the group consisting of Ag, Au and Cu.

Thermoelectric module and heat exchanger

A metal oxide resistor (11) for suppressing variations in resistivity in use in an atmosphere at a high temperature or humidity is disclosed. Such a metal oxide resistor (11) includes a sintered body (12) in which carbon particles having an average grain size of 1 µm or less exist in the grain boundaries of metal oxide particles in an amount of 0.05 to 3 wt%, and electrodes (13) formed on at least two opposing surfaces of the sintered body (12).

Metal oxide resistor, power resistor, and power circuit breaker

A thermoelectric material includes a composition represented by the following formula (A): 
(Ti a1 Zr b1 Hf c1 ) x Ni y Sn 100-x-y   (A)
 
where 0<a1<1, 0<b1<1, 0<c1<1, a1+b1+c1=1, 30≦x≦35, and 30≦y≦35. The composition includes at least two MgAgAs crystal phases different in a lattice constant, and, assuming that X-ray diffraction peak intensity from a (422) diffraction plane of a first MgAgAs crystal phase having a smallest lattice constant and X-ray diffraction peak intensity from a (422) diffraction plane of a second MgAgAs crystal phase having a largest lattice constant be I 1 and I 2 , respectively, a value of I 1 /(I 1 +I 2 ) is in a range of 0.2 to 0.8.

Thermoelectric material and thermoelectric device

A thermoelectric material has a composition expressed by (Fe 1-p V p ) 100-x (Al 1-q Si q ) x (0.35≦p≦0.7, 0.01≦q≦0.7, 20≦x≦30 atomic %). The thermoelectric material includes a crystal phase having an L2 1 structure or a crystal phase having a B2 structure as a main phase.

Naoki Shutoh

Papers

Thermoelectric properties of the TiX(Zr0.5Hf0.5)1 − XNiSn half-Heusler compounds

Thermoelectric module and heat exchanger

Metal oxide resistor, power resistor, and power circuit breaker

Thermoelectric material and thermoelectric device

Thermoelectric material and thermoelectric conversion module using the same