Crystal structure and thermoelectric properties of ReSi1.75 silicide

2002 ◽  
Vol 753 ◽  
Author(s):  
J-J Gu ◽  
K. Kuwabara ◽  
K. Tanaka ◽  
H. Inui ◽  
M. Yamaguchi ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Electron Microscopy ◽  
Thermoelectric Properties ◽  
First Principles ◽  
Figure Of Merit ◽  
First Principles Calculation ◽  
Dimensionless Figure Of Merit ◽  
Transmission Electron ◽  
P Type ◽  
Very High

ABSTRACTThe crystal structure of the defect disilicide formed with Re (ReSi1.75) has been refined by transmission electron microscopy combined with first-principles calculation. The crystal structure is monoclinic with the space group Cm (mc44) due to an ordered arrangement of vacancies on Si sites in the underlying (parent) C11b lattice. The thermoelectric properties of ReSi1.75 are highly anisotropic. Its electrical conduction is of n-type when measure along [001] while it is of p-type when measured along [100]. Although the value of Seebeck coefficient along [100] is moderately high (150–200 μV/K), it is very high along [001] (250–300 μV/K). As a result, a very high value of dimensionless figure of merit (ZT) of 0.7 is achieved at 1073 K when measured along [001].

scholarly journals Enhancement in thermoelectric properties due to Ag nanoparticles incorporated in Bi2Te3 matrix

2019 ◽  
Vol 10 ◽  
pp. 634-643 ◽  
Author(s):  
Srashti Gupta ◽  
Dinesh Chandra Agarwal ◽  
Bathula Sivaiah ◽  
Sankarakumar Amrithpandian ◽  
Kandasami Asokan ◽  
...  
Keyword(s):  
Thermoelectric Properties ◽  
Power Factor ◽  
Figure Of Merit ◽  
Transmission Electron ◽  
High Power Factor ◽  
Different Temperatures ◽  
High Figure ◽  
Filtering Effect ◽  
P Type ◽  
20 Nm

The present study aims to see the enhancement in thermoelectric properties of bismuth telluride (Bi2Te3) annealed at different temperatures (573 and 773 K) through silver (Ag) nano-inclusions (0, 2, 5, 10, 15 and 20 wt %). Transmission electron microscopy (TEM) images of Ag incorporated in Bi2Te3 annealed at 573 K shows tubular, pentagonal, trigonal, circular and hexagonal nanoparticles with sizes of 6–25 nm (for 5 wt % Ag ) and 7–30 nm (for 20 wt % Ag). Ag incorporated in Bi2Te3 annealed at 773 K shows mainly hexagonally shaped structures with particle sizes of 2–20 nm and 40–80 nm (for 5 wt % Ag) and 10–60 nm (for 20 wt % Ag). Interestingly, the samples annealed at 573 K show the highest Seebeck coefficient (S, also called thermopower) at room temperature (p-type behavior) for 5% Ag which is increased ca. five-fold in comparison to Ag-free Bi2Te3, whereas for samples with the same content (5% Ag) annealed at 773 K the increment in thermopower is only about three-fold with a 6.9-fold enhancement of the power factor (S 2σ). The effect of size and shape of the nanoparticles on thermoelectric properties can be understood on the basis of a carrier-filtering effect that results in an increase in thermopower along with a control over the reduction in electrical conductivity to maintain a high power factor yielding a high figure of merit.

Effects of Antimony on the Thermoelectric Properties of the Cubic Pb9.6SbyTe10−xSexMaterials

2005 ◽  
Vol 886 ◽  
Author(s):  
Pierre Ferdinand Poudeu Poudeu ◽  
Jonathan D'Angelo ◽  
Adam Downey ◽  
Robert Pcionek ◽  
Joseph Sootsman ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Thermal Conductivity ◽  
Electrical Conductivity ◽  
Transmission Electron Microscopy ◽  
High Resolution ◽  
Thermoelectric Properties ◽  
Figure Of Merit ◽  
Low Thermal Conductivity ◽  
Intermediate Temperature Range ◽  
Transmission Electron

ABSTRACTThe thermoelectric properties of Pb9.6SbyTe10−xSexwere investigated in the intermediate temperature range of 300 – 700 K. The effect of the variation of Sb content (y) on the electronic properties of the materials is remarkable. Samples with compositions Pb9.6Sb0.2Te10−xSex(y = 0.2) show the best combination of low thermal conductivity with moderate electrical conductivity and thermopower. For Pb9.6Sb0.2Te8Se2(x = 2) a maximum figure of merit of ZT ∼ 1.1 was obtained around 700 K. This value is nearly 1.4 times higher than that of PbTe at 700 K. This enhancement of the figure of merit of Pb9.6Sb0.2Te8Se2derives from its extremely low thermal conductivity (∼0.7 at W/m.K at 700 K). High resolution transmission electron microscopy of Pb9.6Sb0.2Te10−xSexsamples shows broadly distributed Sb-rich nanocrystals, which may be the key feature responsible for the suppression of the thermal conductivity.

Microstructure and Local Mechanical Properties of Skutterudites with Addition of Metallic Borides

2018 ◽  
Vol 784 ◽  
pp. 9-14
Author(s):  
Jiří Buršík ◽  
Vilma Buršíková ◽  
Gerda Rogl ◽  
Peter Rogl
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Figure Of Merit ◽  
Focused Ion Beam ◽  
Ion Beam ◽  
Analytical Transmission Electron Microscopy ◽  
Important Class ◽  
Transmission Electron ◽  
P Type ◽  
Dynamic Nanoindentation

Skutterudites are an important class of thermoelectric p- and n-type materials and they have already achieved fair efficiencies for the conversion of heat to electricity. Nevertheless researchers try to further enhance the figure of merit, ZT, by various ways. In this work we study microstructure and mechanical properties of two thermoelectric materials: an industrial n-type (Mm,Sm)yCo4Sb12 skutterudite and an industrial p-type DDyFe3CoSb12 skutterudite, both mixed with 1 wt.% of Ta0.8Zr0.2B. Thin lamellae were prepared from the compacted materials using a focused ion beam. Analytical transmission electron microscopy was used on lamellae to study details of microstructure. A fine dispersion of precipitates was found both at nanograin boundaries and in their interiors. Quasistatic and dynamic nanoindentation tests were carried out on planar polished sections in the range of applied loads from 0.01 to 10 mN. The results were complemented with quantitative modulus mapping of local mechanical properties with 10-nm resolution.

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 Thermoelectric properties of DO3 V3Al using first principles calculations

RSC Advances ◽  
2017 ◽  
Vol 7 (71) ◽  
pp. 44647-44654 ◽  
Author(s):  
Xiaorui Chen ◽  
Yuhong Huang ◽  
Hong Chen
Keyword(s):  
Thermoelectric Properties ◽  
First Principles ◽  
Figure Of Merit ◽  
Thermoelectric Figure Of Merit ◽  
First Principles Calculations ◽  
Thermoelectric Figure ◽  
P Type

The calculated thermoelectric figure of merit ZT as a function of temperature for n-type antiferromagnetic DO3 V3Al and p-type antiferromagnetic DO3 V3Al is investigated.

scholarly journals Thermoelectric Properties of Cu2Se Synthesized by Hydrothermal Method and Densified by SPS Technique

Materials ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3650
Author(s):  
Paweł Nieroda ◽  
Anna Kusior ◽  
Juliusz Leszczyński ◽  
Paweł Rutkowski ◽  
Andrzej Koleżyński
Keyword(s):  
Electron Microscopy ◽  
Hydrothermal Method ◽  
Thermoelectric Properties ◽  
Composition Studies ◽  
X Ray Diffraction ◽  
Plasma Sintering ◽  
Transmission Electron ◽  
Thermoelectric Transport Properties ◽  
Spark Plasma ◽  
Very High

The aim of the work was to obtain copper (I) selenide Cu2Se material with excellent thermoelectric properties, synthesized using the hydrothermal method and densified by the spark plasma sintering (SPS) method. Chemical and phase composition studies were carried out by X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) methods. Measurements of thermoelectric transport properties, i.e., electrical conductivity, the Seebeck coefficient, and thermal conductivity in the temperature range from 300 to 965 K were carried out. Based on these results, the temperature dependence of the thermoelectric figure of merit ZT as a function of temperature was determined. The obtained, very high ZT parameter (ZT~1.75, T = 965 K) is one of the highest obtained so far for undoped Cu2Se.

scholarly journals Bipolar doping and thermoelectric properties of Zintl arsenide Eu5In2As6

2021 ◽  
Author(s):  
Naoki Tomitaka ◽  
Yosuke Goto ◽  
Kota Morino ◽  
Kazuhisa Hoshi ◽  
Yuki Nakahira ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Electrical Resistivity ◽  
Thermoelectric Properties ◽  
High Performance ◽  
Figure Of Merit ◽  
Lattice Thermal Conductivity ◽  
High Resistivity ◽  
Dimensionless Figure Of Merit ◽  
Recent Developments ◽  
P Type

Zintl compounds exhibit promising thermoelectric properties because of the feasibility of the chemical tuning of their electrical and thermal transport. While most Zintl pnictides are known to show p-type polarity, recent developments in high-performance n-type Mg3Sb2-based thermoelectric materials have encouraged further identification of n-type Zintl pnictides. In this study, we demonstrate the bipolar dopability of the Zintl arsenide Eu5In2As6. The electrical resistivity at 300 K with n-type polarity was decreased to 7.6 x 10^-1 ohmcm using La as an electron dopant. In contrast to the relatively high resistivity of n-type Eu5In2As6, the p-type resistivity at 300 K was decreased to 5.9 x 10^-3 ohmcm with a carrier concentration of 2.8 x 10^20 /cm3 using Zn as a hole dopant. This doping asymmetry is discussed in terms of the weighted mobility of electrons and holes. Furthermore, a very low lattice thermal conductivity of 0.7 W/mK was observed at 773 K, which is comparable to that of the Sb-containing analogue Eu5In2Sb6. The dimensionless figure of merit ZT = 0.29 at 773 K for Zn-doped p-type Eu5In2As6. This study shows that bipolar dopable Eu5In2As6 can be a platform to facilitate a better understanding of the doping asymmetry in Zintl pnictides.

Improvements of Thermoelectric Performances in AgSbTe2 System With in-situ Ag2Te Nano-Precipitations

2010 ◽  
Vol 1267 ◽  
Author(s):  
Shengnan Zhang ◽  
Shenghui Yang ◽  
Guangyu Jiang ◽  
Junjie Shen ◽  
Tiejun Zhu ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Thermoelectric Properties ◽  
Figure Of Merit ◽  
State Of The Art ◽  
Critical Component ◽  
Energy Filtering ◽  
Transmission Electron ◽  
Filtering Effect ◽  
The Relationship

AbstractAgSbTe2 is the critical component in both LAST-m and TAGS-x system, which are two state-of-the-art mid-temperature thermoelectric bulk nanocomposites. By adjusting the Ag2Te/Sb2Te3 ratio, Sb2Te3 and Ag2Te precipitated samples were obtained with x = 0.68 to 0.74 and x = 0.84 to 0.90 (x as in (Ag2Te)x/2(Sb2Te3)1-x/2), respectively. The single phased AgSbTe2 was obtained with the x value of 0.78 and 0.81, which is consistent of the previous results on the phase diagram of (Ag2Te)x(Sb2Te3)1-x system. Comparing the effect of the two different precipitates, Ag2Te are much effective for the improvements of thermoelectric properties in AgSbTe2 nanocomposites. Utilizing the high-resolution transmission electron microscopy, Ag2Te was observed as nanodots and nano-lamellae embedded in the AgSbTe2 matrix, which can be related to the energy filtering effect for the increase of Seebeck coefficient. The relationship among the composition, microstructure and thermoelectric properties was systematically studied. It can be noticed that the thermoelectric properties of AgSbTe2 system are very sensitive to the composition, especially at low temperature. The maximum figure of merit ZT value of 1.53 was obtained at 500 K for Ag0.84Sb1.16Te2.16 with 40% increase comparing with the single phased sample.

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