High Contrast Thermal Conductivity Change in Ni–Mn–In Heusler Alloys near Room Temperature

2019 ◽  
Vol 21 (5) ◽  
pp. 1801342 ◽  
Author(s):  
Qiye Zheng ◽  
Gaohua Zhu ◽  
Zhu Diao ◽  
Debasish Banerjee ◽  
David G. Cahill
Keyword(s):  
Thermal Conductivity ◽  
Room Temperature ◽  
Heusler Alloys ◽  
High Contrast ◽  
Conductivity Change

Synthesis and thermoelectric properties of tantalum-doped ZrNiSn half-Heusler alloys

2014 ◽  
Vol 07 (03) ◽  
pp. 1450032 ◽  
Author(s):  
Degang Zhao ◽  
Min Zuo ◽  
Zhenqing Wang ◽  
Xinying Teng ◽  
Haoran Geng
Keyword(s):  
Thermal Conductivity ◽  
Electrical Conductivity ◽  
Acoustic Phonon ◽  
Figure Of Merit ◽  
Room Temperature ◽  
Phonon Scattering ◽  
Heusler Alloys ◽  
Hot Press ◽  
Arc Melting ◽  
Hot Press Sintering

The Ta -doped ZrNiSn half-Heusler alloys, Zr 1-x Ta x NiSn , were synthesized by arc melting and hot-press sintering. Microstructure of Zr 1-x Ta x NiSn compounds were analyzed and the thermoelectric (TE) properties of Zr 1-x Ta x NiSn compounds were measured from room temperature to 823 K. The electrical conductivity increased with increasing Ta content. The Seebeck coefficient of Zr 1-x Ta x NiSn compounds was sharply decreased with increasing Ta content. The Hall mobility was proportional to T-1.5 above 673 K, indicating that the acoustic phonon scattering was predominant in the temperature range. The thermal conductivity was effectively depressed by introducing Ta substitution. The figure of merit of ZrNiSn compounds was improved due to the decreased thermal conductivity and increased electrical conductivity. The maximum ZT value of 0.60 was achieved for Zr 0.97 Ta 0.03 NiSn sample at 823 K.

Reductions in the Lattice Thermal Conductivity of Ball-milled and Shock compacted TiNiSn1−XSbX Half-Heusler alloys

2001 ◽  
Vol 691 ◽  
Author(s):  
S. Bhattacharya ◽  
Y. Xia ◽  
V. Ponnambalam ◽  
S.J. Poon ◽  
N. Thadani ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Electrical Resistivity ◽  
Figure Of Merit ◽  
Room Temperature ◽  
Lattice Thermal Conductivity ◽  
Heusler Alloys ◽  
Lattice Contribution ◽  
Grain Sizes ◽  
Shock Compaction ◽  
High Figure

ABSTRACTHalf-Heusler alloys are currently being investigated for their potential as thermoelectric materials [1], [2]. They exhibit high negative thermopower (40-250μV/K) and favorable electrical resistivity (0.1-8mW•cm) at room temperature. Attractive power factors (α2σT) of about (0.2-1.0W/m•K) at room temperature and about 4W/m•K at 600K [3] have been reported in these materials. But in order to achieve a high figure-of-merit in the half-Heusler alloys, the relatively high thermal conductivity in these materials (∼ 10 W/m•K) must be reduced. The thermal conductivity in these materials is composed of mainly a lattice contribution, compared to a very small electronic component. The challenge is to reduce the relatively high lattice thermal conductivity in these materials. Reported in this paper is a significant reduction of lattice thermal conductivity (∼1.5 - 3.5W/m•K) in some Ti-based half-Heusler alloys. Samples have been prepared by ball milling and followed by shock-compaction that has resulted into reduced grain sizes in these materials. The effects of the microstructure on the thermal transport properties of the Half-Heusler alloys have been investigated and are presented and discussed herein.

Effect of substitutional doping on the thermal conductivity of Ti-based Half-Heusler compounds

2000 ◽  
Vol 626 ◽  
Author(s):  
S. Bhattacharya ◽  
V. Ponnambalam ◽  
A.L. Pope ◽  
Y. Xia ◽  
S.J. Poon ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Room Temperature ◽  
Heusler Alloys ◽  
Heusler Compounds ◽  
Large Power ◽  
Substitutional Doping ◽  
Sb Doping ◽  
Systematic Determination ◽  
Factor Α

ABSTRACTHalf-Heusler alloys with the general formula TiNiSn1-XSbX are currently being investigated for their potential as thermoelectric (TE) materials. 1,2,3,4 These materials exhibit high thermopower (40–250μV/K) and low electrical resistivity values (0.1 - 8mΩ-cm) which yields a relatively large power factor (α2σT) of (0.2 - 1.0) W/m♦K at room temperature. The challenge is to reduce the relatively high thermal conductivity (≈ 10 W/m♦K) that is evident in these materials. The focus of this research is to investigate the effect of Sb-doping on the Sn site and Zr doping on the Ti site on the thermal conductivity of TiNiSn. Highly doped half-Heusler alloys have shown marked reduction in thermal conductivity to values on the order of 3.5 - 4.5 W/m♦K. Systematic determination of thermal conductivity in a variety of these doped materials as well as Sb and Zr doped TiNiSn are presented and discussed.

High thermal conductivity of pure dense SiC ceramics prepared via HTPVT

2019 ◽  
Vol 12 (03) ◽  
pp. 1950032 ◽  
Author(s):  
Yuchen Deng ◽  
Yaming Zhang ◽  
Nanlong Zhang ◽  
Qiang Zhi ◽  
Bo Wang ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Silicon Carbide ◽  
Grain Size ◽  
Phase Composition ◽  
Room Temperature ◽  
Vapor Transport ◽  
Physical Vapor Transport ◽  
Growth Substrate ◽  
Sic Ceramics ◽  
Evolution Of Microstructure

Pure dense silicon carbide (SiC) ceramics were obtained via the high-temperature physical vapor transport (HTPVT) method using graphite paper as the growth substrate. The phase composition, the evolution of microstructure, the thermal diffusivity and thermal conductivity at RT to 200∘C were investigated. The obtained samples had a relative density of higher than 98.7% and a large grain size of 1[Formula: see text]mm, the samples also had a room-temperature thermal conductivity of [Formula: see text] and with the temperature increased to 200∘C, the thermal conductivity still maintained at [Formula: see text].

scholarly journals Local ferroelectric polarization switching driven by nanoscale distortions in thermoelectric $${\text {Sn}}_{0.7}{\text {Ge}}_{0.3}{\text {Te}}$$

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Aastha Vasdev ◽  
Moinak Dutta ◽  
Shivam Mishra ◽  
Veerpal Kaur ◽  
Harleen Kaur ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Figure Of Merit ◽  
Room Temperature ◽  
Lattice Thermal Conductivity ◽  
Direct Evidence ◽  
Temperature Dependent ◽  
Force Microscopy ◽  
Ferroelectric Domains ◽  
Pdf Analysis ◽  
Ferroelectric Transition Temperature

AbstractA remarkable decrease in the lattice thermal conductivity and enhancement of thermoelectric figure of merit were recently observed in rock-salt cubic SnTe, when doped with germanium (Ge). Primarily, based on theoretical analysis, the decrease in lattice thermal conductivity was attributed to local ferroelectric fluctuations induced softening of the optical phonons which may strongly scatter the heat carrying acoustic phonons. Although the previous structural analysis indicated that the local ferroelectric transition temperature would be near room temperature in $${\text {Sn}}_{0.7}{\text {Ge}}_{0.3}{\text {Te}}$$ Sn 0.7 Ge 0.3 Te , a direct evidence of local ferroelectricity remained elusive. Here we report a direct evidence of local nanoscale ferroelectric domains and their switching in $${\text {Sn}}_{0.7}{\text {Ge}}_{0.3}{\text {Te}}$$ Sn 0.7 Ge 0.3 Te using piezoeresponse force microscopy(PFM) and switching spectroscopy over a range of temperatures near the room temperature. From temperature dependent (250–300 K) synchrotron X-ray pair distribution function (PDF) analysis, we show the presence of local off-centering distortion of Ge along the rhombohedral direction in global cubic $${\text {Sn}}_{0.7}{\text {Ge}}_{0.3}{\text {Te}}$$ Sn 0.7 Ge 0.3 Te . The length scale of the $${\text {Ge}}^{2+}$$ Ge 2 + off-centering is 0.25–0.10 Å near the room temperatures (250–300 K). This local emphatic behaviour of cation is the cause for the observed local ferroelectric instability, thereby low lattice thermal conductivity in $${\text {Sn}}_{0.7}{\text {Ge}}_{0.3}{\text {Te}}$$ Sn 0.7 Ge 0.3 Te .

Thermal Conductivity of Room Temperature Deep Eutectic Solvents

2021 ◽  
Author(s):  
Noor Albayati ◽  
Mohammed Kadhom ◽  
Ghassan Abdullah ◽  
Suhaib Salih
Keyword(s):  
Thermal Conductivity ◽  
Room Temperature ◽  
Deep Eutectic Solvents

scholarly journals Above-room-temperature giant thermal conductivity switching in spintronic multilayers

2021 ◽  
Vol 118 (4) ◽  
pp. 042409
Author(s):  
Hiroyasu Nakayama ◽  
Bin Xu ◽  
Sotaro Iwamoto ◽  
Kaoru Yamamoto ◽  
Ryo Iguchi ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Room Temperature ◽  
Conductivity Switching

scholarly journals Research on Thermal Stability and Properties of Ca3ZrSi2O9 as Potential T/EBC Materials

Coatings ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 583
Author(s):  
Yangyang Pan ◽  
Bo Liang ◽  
Yaran Niu ◽  
Dijuan Han ◽  
Dongdong Liu ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Thermal Stability ◽  
Fracture Toughness ◽  
Room Temperature ◽  
Coefficient Of Thermal Expansion ◽  
Atmospheric Plasma ◽  
Thermal Barrier ◽  
Mechanical And Thermal Properties ◽  
Self Healing ◽  
Barrier Coating

In this study, a new coating material for thermal barrier coating (TBC) or environment barrier coating (EBC) application, Ca3ZrSi2O9 (CZSO), was synthesized and prepared by atmospheric plasma spray (APS) technology. The evolution of the phases and microstructures of the coatings with different thermal-aged were characterized by XRD, XRF, EDS and SEM, respectively. The thermal stability was measured by TG-DTA and DSC. The mechanical and thermal properties, including Vickers hardness (HV), fracture toughness (KIC), thermal conductivity () and coefficient of thermal expansion (CTE) were focused on. It was found that the as-sprayed CZSO coating contained amorphous phase. Crystalline transformation happened at 900–960 ∘C and no mass changes took place from room temperature (RT) to 1300 ∘C. The phenomena of microcrack self-healing and composition uniformity were observed during thermal aging. The of coating was very low at about 0.57–0.80 Wm−1K−1 in 200–1200 ∘C. The combined properties indicated that the CZSO coating might be a potential T/EBC material.

Thermoelectric Properties of Semiconducting Intermetallic Compounds: FeGa3and RuGa3

2003 ◽  
Vol 793 ◽  
Author(s):  
Y. Amagai ◽  
A. Yamamoto ◽  
C. H. Lee ◽  
H. Takazawa ◽  
T. Noguchi ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Electrical Resistivity ◽  
High Temperature ◽  
Seebeck Coefficient ◽  
Transport Properties ◽  
Figure Of Merit ◽  
Room Temperature ◽  
Thermoelectric Figure Of Merit ◽  
Thermoelectric Figure ◽  
High Seebeck Coefficient

ABSTRACTWe report transport properties of polycrystalline TMGa3(TM = Fe and Ru) compounds in the temperature range 313K<T<973K. These compounds exhibit semiconductorlike behavior with relatively high Seebeck coefficient, electrical resistivity, and Hall carrier concentrations at room temperature in the range of 1017- 1018cm−3. Seebeck coefficient measurements reveal that FeGa3isn-type material, while the Seebeck coefficient of RuGa3changes signs rapidly from large positive values to large negative values around 450K. The thermal conductivity of these compounds is estimated to be 3.5Wm−1K−1at room temperature and decreased to 2.5Wm−1K−1for FeGa3and 2.0Wm−1K−1for RuGa3at high temperature. The resulting thermoelectric figure of merit,ZT, at 945K for RuGa3reaches 0.18.

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