Recent Developments in β‐Zn4Sb3 Based Thermoelectric Compounds

Zou, Tianhua; Xie, Wenjie; Feng, Jian; Qin, Xiaoying; Weidenkaff, Anke

doi:10.1155/2015/642909

Cited by 10 publications

(4 citation statements)

References 115 publications

(98 reference statements)

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“…For the thermoelectric applications, the half-Heusler materials are sometimes deliberately synthesized 37,38 with an excess of element A which is supposed to occupy each second interstitial site in the rocksalt lattice BC. While the solubility of the A species in the half-Heusler alloy is rather limited 9 , concentrations of A of the order of a few percent may still be reached by occupying additional interstitial sites by A atoms.…”

Section: B Defects Of the A Sublatticementioning

confidence: 99%

Ternary semiconductors NiZrSn and CoZrBi with half-Heusler structure: A first-principles study

Fiedler

Kratzer

2016

Phys. Rev. B

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The ternary semiconductors NiZrSn and CoZrBi with C1 b crystal structure are introduced by calculating their basic structural, electronic and phononic properties using density functional theory. Both the gradient-corrected PBE functional and the hybrid functional HSE06 are employed. While NiZrSn is found to be a small-band-gap semiconductor (Eg = 0.46 eV in PBE and 0.60 eV in HSE06), CoZrBi has a band gap of 1.01 eV in PBE (1.34 eV in HSE06). Moreover, effective masses and deformation potentials are reported. In both materials ABC, the intrinsic point defects introduced by species A (Ni or Co) are calculated. The Co-induced defects in CoZrBi are found to have a higher formation energy compared to Ni-induced defects in NiZrSn. The interstitial Ni atom (Nii ) as well as the VNiNii complex introduce defect states in the band gap, whereas the Ni vacancy (VNi) only reduces the size of the band gap. While Nii is electrically active and may act as a donor, the other two types of defects may compensate extrinsic doping. In CoZrBi, only the VCoCoi complex introduces a defect state in the band gap. Motivated by the reported use of NiZrSn for thermoelectric applications, the Seebeck coefficient of both materials, both in the p-type and the n-type regime, is calculated. We find that CoZrBi displays a rather large thermopower of up to 500µV/K when p-doped, whereas NiZrSn possesses its maximum thermopower in the n-type regime. The reported difficulties in achieving p-type doping in NiZrSn could be rationalized by the unintended formation of Niin conjunction with extrinsic acceptors, resulting in their compensation. Moreover, it is found that all types of defects considered, when present in concentrations as large as 3%, tend to reduce the thermopower compared to ideal bulk crystals at T = 600 K. For NiZrSn, the calculated thermodynamic data suggest that additional Ni impurities could be removed by annealing, leading to precipitation of a metallic Ni2ZrSn phase.

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Section: B Defects Of the A Sublatticementioning

confidence: 99%

Ternary semiconductors NiZrSn and CoZrBi with half-Heusler structure: A first-principles study

Fiedler

Kratzer

2016

Phys. Rev. B

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“…A very high barrier will damage electronic transport, whereas a low barrier will offer no filtering advantage and could also allow high thermal conductivity. In other examples, the β-Zn 4 Sb 3 system, embedded with (Bi 2 Te 3 ) 0.2 (Sb 2 Te 3 ) 0.8 resulted in a 30% increase in the PF as a result of energy filtering and a ZT ∼1.1 at 648 K was achieved [133,134]. Similarly, an interface between β-Zn 4 Sb 3 and Cu 3 SbSe 4 creates an effective barrier produced from band bending which improves the PF [135].…”

Section: Introductionmentioning

confidence: 99%

Hierarchically nanostructured thermoelectric materials: challenges and opportunities for improved power factors

et al. 2020

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The field of thermoelectric materials has undergone a revolutionary transformation over the last couple of decades as a result of the ability to nanostructure and synthesize myriads of materials and their alloys. The ZT figure of merit, which quantifies the performance of a thermoelectric material has more than doubled after decades of inactivity, reaching values larger than two, consistently across materials and temperatures. Central to this ZT improvement is the drastic reduction in the material thermal conductivity due to the scattering of phonons on the numerous interfaces, boundaries, dislocations, point defects, phases, etc., which are purposely included. In these new generation of nanostructured materials, phonon scattering centers of different sizes and geometrical configurations (atomic, nano- and macro-scale) are formed, which are able to scatter phonons of mean-free-paths across the spectrum. Beyond thermal conductivity reductions, ideas are beginning to emerge on how to use similar hierarchical nanostructuring to achieve power factor improvements. Ways that relax the adverse interdependence of the electrical conductivity and Seebeck coefficient are targeted, which allows power factor improvements. For this, elegant designs are required, that utilize for instance non-uniformities in the underlying nanostructured geometry, non-uniformities in the dopant distribution, or potential barriers that form at boundaries between materials. A few recent reports, both theoretical and experimental, indicate that extremely high power factor values can be achieved, even for the same geometries that also provide ultra-low thermal conductivities. Despite the experimental complications that can arise in having the required control in nanostructure realization, in this colloquium, we aim to demonstrate, mostly theoretically, that it is a very promising path worth exploring. We review the most promising recent developments for nanostructures that target power factor improvements and present a series of design ‘ingredients’ necessary to reach high power factors. Finally, we emphasize the importance of theory and transport simulations for materialoptimization, and elaborate on the insight one can obtain from computational tools routinely used in the electronic device communities. Graphical abstract

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“…The existence of such band resonant states has been predicted theoretically and confirmed experimentally in studies with Tl‐doped PbTe . Enhancing the Seebeck coefficient via creating band resonant states also works well in a number of other TE materials …”

Section: Microstructure Dependence Of Electronic and Thermal Transpormentioning

confidence: 62%

Multi‐Scale Microstructural Thermoelectric Materials: Transport Behavior, Non‐Equilibrium Preparation, and Applications

et al. 2017

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Considering only about one third of the world's energy consumption is effectively utilized for functional uses, and the remaining is dissipated as waste heat, thermoelectric (TE) materials, which offer a direct and clean thermal-to-electric conversion pathway, have generated a tremendous worldwide interest. The last two decades have witnessed a remarkable development in TE materials. This Review summarizes the efforts devoted to the study of non-equilibrium synthesis of TE materials with multi-scale structures, their transport behavior, and areas of applications. Studies that work towards the ultimate goal of developing highly efficient TE materials possessing multi-scale architectures are highlighted, encompassing the optimization of TE performance via engineering the structures with different dimensional aspects spanning from the atomic and molecular scales, to nanometer sizes, and to the mesoscale. In consideration of the practical applications of high-performance TE materials, the non-equilibrium approaches offer a fast and controllable fabrication of multi-scale microstructures, and their scale up to industrial-size manufacturing is emphasized here. Finally, the design of two integrated power generating TE systems are described-a solar thermoelectric-photovoltaic hybrid system and a vehicle waste heat harvesting system-that represent perhaps the most important applications of thermoelectricity in the energy conversion area.

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Recent Developments in β‐Zn₄Sb₃ Based Thermoelectric Compounds

Cited by 10 publications

References 115 publications

Ternary semiconductors NiZrSn and CoZrBi with half-Heusler structure: A first-principles study

Ternary semiconductors NiZrSn and CoZrBi with half-Heusler structure: A first-principles study

Hierarchically nanostructured thermoelectric materials: challenges and opportunities for improved power factors

Multi‐Scale Microstructural Thermoelectric Materials: Transport Behavior, Non‐Equilibrium Preparation, and Applications

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