scholarly journals Synthesis of Nb0.8Hf0.2FeSb0.98Sn0.02 and Hf0.25Zr0.25Ti0.5NiSn0.98Sb0.02 Half-Heusler Materials and Fabrication of Thermoelectric Generators

2021 ◽  
Vol 59 (12) ◽  
pp. 904-910
Author(s):  
Sung-Jae Joo ◽  
Ji-Hee Son ◽  
JeongIn Jang ◽  
Bong-Seo Kim ◽  
Bok-Ki Min
Keyword(s):  
Temperature Gradient ◽  
Maximum Power ◽  
Induction Melting ◽  
Figures Of Merit ◽  
Arc Melting ◽  
Plasma Sintering ◽  
Melting Technique ◽  
Spark Plasma ◽  
P Type ◽  
Metal Layers

In this study, half-Heusler (HH) thermoelectric materials Nb0.8Hf0.2FeSb0.98Sn0.02 (p-type) and Hf0.25Zr0.25Ti0.5NiSn0.98Sb0.02 (n-type) were synthesized using induction melting and spark plasma sintering. For alloying, a conventional induction melting technique was employed rather than arc melting, for mass production compatibility, and the thermoelectric properties of the materials were analyzed. The maximum dimensionless figures of merit (zTmax) were 0.75 and 0.82 for the p- and n-type material at 650 oC and 600 oC, respectively. These materials were then used to fabricate generator modules, wherein two pairs of p- and nlegs without interfacial metal layers were brazed on direct bonded copper (DBC)/Al2O3 substrates using a Zrbased alloy. A maximum power of 0.57 W was obtained from the module by applying a temperature gradient of 476 oC, which corresponds to a maximum power density of 1.58 W cm -2 when normalized by the area of the material. The maximum electrical conversion efficiency of the module was 3.22% at 476 oC temperature gradient. This value was negatively affected by the non-negligible contact resistivity of the brazed interfaces, which ranged from 6.63 × 10 -9 Ωm2 to 7.54 × 10 -9 Ω m2 at hot-side temperatures of 190 oC and 517 oC, respectively. The low electrical resistivity of the HH materials makes it especially important to develop a brazing technique for ultralow resistance contacts.

scholarly journals Thermal and Electronic Transport Properties of the Half-Heusler Phase ScNiSb

Materials ◽  
2019 ◽  
Vol 12 (10) ◽  
pp. 1723 ◽  
Author(s):  
Karol Synoradzki ◽  
Kamil Ciesielski ◽  
Igor Veremchuk ◽  
Horst Borrmann ◽  
Przemysław Skokowski ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Electrical Resistivity ◽  
Small Magnitude ◽  
Single Phase Sample ◽  
Heusler Phase ◽  
Temperature Range ◽  
Arc Melting ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
P Type

Thermoelectric properties of the half-Heusler phase ScNiSb (space group F 4 ¯ 3m) were studied on a polycrystalline single-phase sample obtained by arc-melting and spark-plasma-sintering techniques. Measurements of the thermopower, electrical resistivity, and thermal conductivity were performed in the wide temperature range 2–950 K. The material appeared as a p-type conductor, with a fairly large, positive Seebeck coefficient of about 240 μV K−1 near 450 K. Nevertheless, the measured electrical resistivity values were relatively high (83 μΩm at 350 K), resulting in a rather small magnitude of the power factor (less than 1 × 10−3 W m−1 K−2) in the temperature range examined. Furthermore, the thermal conductivity was high, with a local minimum of about 6 W m−1 K−1 occurring near 600 K. As a result, the dimensionless thermoelectric figure of merit showed a maximum of 0.1 at 810 K. This work suggests that ScNiSb could be a promising base compound for obtaining thermoelectric materials for energy conversion at high temperatures.

Fabrication of Mg2Si from a Reused-silicon Source and its Thermoelectric Characteristics

2007 ◽  
Vol 1044 ◽  
Author(s):  
Masayasu Akasaka ◽  
Tsutomu Iida ◽  
Youhiko Mito ◽  
Takeru Omori ◽  
Yohei Oguni ◽  
...  
Keyword(s):  
Thermoelectric Properties ◽  
Power Factor ◽  
Figure Of Merit ◽  
Silicon Source ◽  
Figures Of Merit ◽  
Dimensionless Figure Of Merit ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
P Type ◽  
Type Sample

AbstractPolycrystalline Mg2Si was fabricated from a reused-Silicon source, based on Si sludge, using Spark Plasma Sintering technique. The n-type and p-type dopants, bismuth (Bi) and silver (Ag), respectively, were incorporated into the Mg2Si. The thermoelectric properties were estimated from 300 to 873K. The power factors of undoped and Bi-doped samples from the reused-Si source were comparable to those from a solar grade Si source (99.99999%). The power factor was estimated to be 2.5 × 10-5 W/cmK2 for the Bi-doped sample from the reused-Si source. However, the power factor of the Ag-doped, p-type sample from the reused-Si source was lower than that from solar grade Si source. The dimensionless figures of merit of samples from the resused-Si source were slightly lower than those from a solar grade Si source. The dimensionless figure of merit was estimated to be 0.53 at 812 K for Bi-doped sample from the reused-Si source.

scholarly journals Extremely Fast and Cheap Densification of Cu2S by Induction Melting Method

Materials ◽  
2021 ◽  
Vol 14 (23) ◽  
pp. 7311
Author(s):  
Paweł Nieroda ◽  
Krzysztof Ziewiec ◽  
Juliusz Leszczyński ◽  
Paweł Rutkowski ◽  
Andrzej Koleżyński
Keyword(s):  
Chemical Composition ◽  
Figure Of Merit ◽  
Induction Melting ◽  
X Ray Diffraction ◽  
Temperature Range ◽  
Plasma Sintering ◽  
Melting Technique ◽  
Thermoelectric Transport Properties ◽  
Spark Plasma ◽  
Phase And Chemical Composition

The aim of this work was to obtain dense Cu2S superionic thermoelectric materials, homogeneous in terms of phase and chemical composition, using a very fast and cheap induction-melting technique. The chemical composition was investigated via scanning electron microscopy (SEM) combined with an energy-dispersive spectroscopy (EDS) method, and the phase composition was established by X-ray diffraction (XRD). The thermoelectric figure of merit ZT was determined on the basis of thermoelectric transport properties, i.e., Seebeck coefficient, electrical and thermal conductivity in the temperature range of 300–923 K. The obtained values of the ZT parameter are comparable with those obtained using the induction hot pressing (IHP) technique and about 30–45% higher in the temperature range of 773–923 K in comparison with Cu2S samples densified with the spark plasma sintering (SPS) technique.

Fabrication of Bi-Te Based Thermoelectric Semiconductors by Using Hybrid Powders

2005 ◽  
Vol 297-300 ◽  
pp. 875-880
Author(s):  
Cheol Ho Lim ◽  
Ki Tae Kim ◽  
Yong Hwan Kim ◽  
Dong Choul Cho ◽  
Young Sup Lee ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Single Crystals ◽  
Thermoelectric Properties ◽  
Thermoelectric Materials ◽  
Figure Of Merit ◽  
Bending Strength ◽  
Mixing Ratio ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
P Type

P-type Bi0.5Sb1.5Te3 compounds doped with 3wt% Te were fabricated by spark plasma sintering and their mechanical and thermoelectric properties were investigated. The sintered compounds with the bending strength of more than 50MPa and the figure-of-merit 2.9×10-3/K were obtained by controlling the mixing ratio of large powders (PL) and small powders (PS). Compared with the conventionally prepared single crystal thermoelectric materials, the bending strength was increased up to more than three times and the figure-of-merit Z was similar those of single crystals. It is expected that the mechanical properties could be improved by using hybrid powders without degradation of thermoelectric properties.

Thermoelectric properties of undoped p-type CoSb3 prepared by vertical Bridgman crystal growth and spark plasma sintering

2006 ◽  
Vol 415 (1-2) ◽  
pp. 251-256 ◽  
Author(s):  
Satoru Furuyama ◽  
Tsutomu Iida ◽  
Shinsuke Matsui ◽  
Masayasu Akasaka ◽  
Keishi Nishio ◽  
...  
Keyword(s):  
Crystal Growth ◽  
Spark Plasma Sintering ◽  
Thermoelectric Properties ◽  
Plasma Sintering ◽  
Vertical Bridgman ◽  
Spark Plasma ◽  
Bridgman Crystal Growth ◽  
P Type

Compression stress strengthening modelling of a ultrafine-grained equiatomic SPS CoCrFeNiNb high-entropy alloy

2020 ◽  
pp. 095440622094324
Author(s):  
Marcello Cabibbo ◽  
Filip Průša ◽  
Alexandra Šenková ◽  
Andrea Školáková ◽  
Vojtěch Kučera ◽  
...  
Keyword(s):  
Powder Metallurgy ◽  
Mechanical Alloying ◽  
Oxide Phase ◽  
High Entropy Alloy ◽  
Induction Melting ◽  
High Entropy Alloys ◽  
High Entropy ◽  
Plasma Sintering ◽  
Transmission Electron ◽  
Spark Plasma

High-entropy alloys are known to show exceptionally high mechanical properties, both compression and tensile strength, and unique physical properties, such as their phase stability. These quite unusual properties are primarily due to the microstructure generated by mechanical alloying processes, such as conventional induction arc melting, powder metallurgy, or mechanical alloying. In the present study, an equiatomic CoCrFeNiNb high-entropy alloy was prepared by a sequence of conventional induction melting, powder metallurgy, and compaction via spark plasma sintering. The high-entropy alloys showed uniform sub-micrometer grain microstructure consisted by a mixture of an fcc solid solution strengthened by a hcp Laves phase and a third intergranular oxide phase. The as-cast high-entropy alloys showed an ultimate compression strength (UCS) of ∼1400 MPa, which after sintering and compaction at 1273 K increased up to ∼2400 MPa. Extensive transmission electron microscopy quantitative analyses were carried out to model the UCS. A quite good agreement between the microstructure-strengthening model and the experimental UCS was found.

The Influence of RuO2 Addition on the Thermoelectric Properties of BiSbTe Alloys

2012 ◽  
Vol 512-515 ◽  
pp. 1651-1654 ◽  
Author(s):  
Yu Kun Xiao ◽  
Zhi Xiang Li ◽  
Jun Jiang ◽  
Sheng Hui Yang ◽  
Ting Zhang ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Thermoelectric Properties ◽  
Lattice Thermal Conductivity ◽  
Combined Process ◽  
Plasma Sintering ◽  
The Matrix ◽  
Spark Plasma ◽  
Xrd Patterns ◽  
Factor Α ◽  
P Type

P-type BiSbTe/RuO2 composite was fabricated using a combined process of melting and spark plasma sintering. The XRD patterns showed that RuO2 reacted with the matrix for the RuO2 content of 1.0 wt% and 4.0 wt% samples. The measured thermoelectric properties showed that the highest electrical conductivity was obtained for the sample with 2.0 wt% RuO2. The power factor (α2σ/κ) decreased with the increase of RuO2 below 450 K. The lattice thermal conductivity was lower than that of BiSbTe over the whole temperature range for BiSbTe/2.0 wt% RuO2.

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