scholarly journals Mechanosynthesis and Thermoelectric Properties of Fe, Zn, and Cd-Doped P-Type Tetrahedrite: Cu12-xMxSb4S13

Materials ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3448
Author(s):  
Francisco Arturo López Cota ◽  
José Alonso Díaz-Guillén ◽  
Oscar Juan Dura ◽  
Marco Antonio López de la Torre ◽  
Joelis Rodríguez-Hernández ◽  
...  
Keyword(s):  
Thermoelectric Properties ◽  
Figure Of Merit ◽  
Powder Processing ◽  
High Energy ◽  
Secondary Phases ◽  
Ambient Conditions ◽  
Cadmium Sulfate ◽  
Electrical Conductivities ◽  
Compositional Changes ◽  
P Type

This contribution deals with the mechanochemical synthesis, characterization, and thermoelectric properties of tetrahedrite-based materials, Cu12-xMxSb4S13 (M = Fe2+, Zn2+, Cd2+; x = 0, 1.5, 2). High-energy mechanical milling allows obtaining pristine and substituted tetrahedrites, after short milling under ambient conditions, of stoichiometric mixtures of the corresponding commercially available binary sulfides, i.e., Cu2S, CuS, Sb2S3, and MS (M = Fe2+, Zn2+, Cd2+). All the target materials but those containing Cd were obtained as single-phase products; some admixture of a hydrated cadmium sulfate was also identified by XRD as a by-product when synthesizing Cu10Cd2Sb4S13. The as-obtained products were thermally stable when firing in argon up to a temperature of 350–400 °C. Overall, the substitution of Cu(II) by Fe(II), Zn(II), or Cd(II) reduces tetrahedrites’ thermal and electrical conductivities but increases the Seebeck coefficient. Unfortunately, the values of the thermoelectric figure of merit obtained in this study are in general lower than those found in the literature for similar samples obtained by other powder processing methods; slight compositional changes, undetected secondary phases, and/or deficient sintering might account for some of these discrepancies.

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.

LOW TEMPERATURE THERMOELECTRIC PROPERTIES AND AGING PHENOMENA OF NANOSTRUCTURED p-TYPE Bi2-XSbXTe3 (x = 1.46, 1.48, 1.52 AND 1.55)

2013 ◽  
Vol 06 (05) ◽  
pp. 1340008 ◽  
Author(s):  
DALE HITCHCOCK ◽  
YEN-LIANG LIU ◽  
YUFEI LIU ◽  
TERRY M. TRITT ◽  
JIAN HE ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Low Temperature ◽  
Thermoelectric Properties ◽  
Optimal Composition ◽  
Ambient Conditions ◽  
Bulk Materials ◽  
The Past ◽  
Aging Phenomena ◽  
P Type ◽  
Cold Pressed

Over the past decade the widely used p-type ( Bi 2-x Sb x) Te 3 bulk thermoelectric materials have been subject to various nanostructuring processes for higher thermoelectric performance. However, these nanostructuring processing were conducted on compositions optimized for bulk materials (x ~ 1.52–1.55). This leads to the question of whether the optimal composition for bulk materials is the same for their nanoscale counterparts. In this work we hydrothermally grew Bi 2-x Sb x Te 3 nanopowders (nominally, x = 1.46, 1.48, 1.52 and 1.55) and measured their thermoelectric properties on cold-pressed vacuum-sintered pellets (74–78% of the theoretical density) below 300 K. The measurements were conducted 18 months apart to probe the aging phenomena, with the samples stored in ambient conditions. We have found that (i) the peak of thermopower shifts to lower temperatures upon nanostructuring but it shifts back to higher temperatures upon aging; (ii) the electrical conductivity degrades by a factor of 1.5–2.3 upon aging while the temperature dependence is largely retained; and (iii) the ZT of freshly made samples is sensitive to the x value, a maximum ZT ~ 1.25(~ 0.62) at ~ 270 K (~ 255 K) was attained in the freshly made sample x = 1.55(x = 1.46), respectively; while the ZT of aged samples is significantly lowered by a factor of 2–4 but lesser x-dependent. These observations have been discussed in the context of charge buildup and compensation at grain boundaries.

Thermoelectric Properties of Bi2Te3-ySey Bulk Materials Synthesized by Melting-Grinding Process

2018 ◽  
Vol 773 ◽  
pp. 145-151
Author(s):  
Min Soo Park ◽  
Gook Hyun Ha ◽  
Hye Young Koo ◽  
Yong Ho Park
Keyword(s):  
Thermal Conductivity ◽  
Thermoelectric Properties ◽  
Figure Of Merit ◽  
Room Temperature ◽  
Thermal Characteristics ◽  
Grinding Process ◽  
Alloy Scattering ◽  
Temperature Range ◽  
P Type ◽  
Optimal Effect

The Bi–Te thermoelectric system shows an excellent figure of merit (ZT) near room temperature. Research on increasing the ZT value for n‑type Bi–Te is imperative because the thermoelectric properties of this compound are inferior to those of the p-type material. For this purpose, n-type Bi2Te3-ySey powders with various amounts of Se dopant (0.3 ≤ y ≤ 0.6) were synthesized by a vacuum melting-grinding process to improve the physical properties. The ZT value of the sintered bodies was investigated in the temperature range of 298–423 K with regard to the electrical and thermal characteristics. As the Se content increased, the electrical conductivity decreased owing to a reduction in the carrier concentration, which improved the overall value of ZT. The thermal conductivity clearly decreased as the Se content increased in the temperature range of 298–373 K due to increased alloy scattering, as well as a reduction in the lattice thermal conductivity caused by crystal grain boundary scattering. At room temperature, Bi2Te2.7Se0.3 (y = 0.3) exhibited the highest ZT of 0.85. At increased temperatures, the ZT value was highest for Bi2Te2.55Se0.45 (y = 0.45), indicating that the optimal effect of the Se dopants varies depending on the temperature range.

scholarly journals Thermoelectric Properties of Sr1-3x/2Lax/2Smx/2TiO3-δ (0.05 ≤ x ≤ 0.30) Ceramics

2021 ◽  
Author(s):  
Adindu C. Iyasara
Keyword(s):  
Thermoelectric Properties ◽  
Figure Of Merit ◽  
Ceramic Powders ◽  
Thermoelectric Figure ◽  
Seebeck Coefficients ◽  
Reducing Gas ◽  
Maximum Value ◽  
Heat Treated ◽  
Electrical Conductivities ◽  
Sintering Processes

Abstract Influence of strongly reducing processing atmosphere on Sr-vacancy Sr1-3x/2Lax/2Smx/2TiO3-δ (x = 0.05, 0.10, 0.15, 0.20, 0.30) ceramics was investigated. The ceramic powders were prepared by the solid-state reaction (SSR) method, and heat treated in 5 % H2/N2 reducing gas at 1573 K for 6 h and 1773 K for 8 h for calcination and sintering processes, respectively. Thermoelectric properties of Sr1-3x/2Lax/2Smx/2TiO3-δ ceramics were evaluated from 573 to 973 K. Their electrical conductivities increased with carrier concentration and also decreased with temperature, indicating metallic behaviour. The Seebeck coefficients showed n-type behaviour and increased with temperature. Additionally, the total thermal conductivities exhibited low values, with a minimum value, 2.67 W/m. K for x = 0.20 ceramics at 973 K. A maximum thermoelectric figure of merit, ZT = 0.30 at 973 K was reached for Sr0.7La0.1Sm0.1TiO3-δ ceramics, which is 20 % higher than the maximum value reported previously for La-Sm electron doped SrTiO3 ceramics.

scholarly journals Development of Spark Plasma Syntering (SPS) technology for preparation of nanocrystalline p-type thermoelctrics based on (BiSb)2Te3

2020 ◽  
Vol 21 (4) ◽  
pp. 628-634
Author(s):  
O. Kostyuk ◽  
B. Dzundza ◽  
M. Maksymuk ◽  
V. Bublik ◽  
L. Chernyak ◽  
...  
Keyword(s):  
Thermoelectric Properties ◽  
Figure Of Merit ◽  
Antimony Telluride ◽  
Bismuth Antimony Telluride ◽  
Thermoelectric Figure ◽  
Temperature Range ◽  
Plasma Sintering ◽  
Different Temperatures ◽  
Spark Plasma ◽  
P Type

Bismuth antimony telluride is the most commonly used commercial thermoelectric material for power generation and refrigeration over the temperature range of 200–400 K. Improving the performance of these materials is a complected balance of optimizing thermoelectric properties. Decreasing the grain size of Bi0.5Sb1.5Te3 significantly reduces the thermal conductivity due to the scattering phonons on the grain boundaries. In this work, it is shown the advances of spark plasma sintering (SPS) for the preparation of nanocrystalline p-type thermoelectrics based on Bi0.5Sb1.5Te3 at different temperatures (240, 350, 400oC). The complex study of structural and thermoelectric properties of Bi0.5Sb1.5Te3 were presented. The high dimensionless thermoelectric figure of merit ZT ~ 1 or some more over 300–400 K temperature range for nanocrystalline p-type Bi0.5Sb1.5Te3 was obtained.

Thermoelectric properties of germanium telluride with fine-grained structure

2020 ◽  
Vol 11 ◽  
pp. 15-25
Author(s):  
L. D. Ivanova ◽  
◽  
Yu. V. Granatkina ◽  
I. Yu. Nikhezina ◽  
A. G. Malchev ◽  
...  
Keyword(s):  
Thermoelectric Properties ◽  
Melt Spinning ◽  
High Energy ◽  
Grain Structure ◽  
Thermoelectric Efficiency ◽  
Fine Grained ◽  
Germanium Telluride ◽  
Fine Grained Structure ◽  
Properties Of Materials ◽  
P Type

The microstructure and thermoelectric properties of materials based on germanium telluride p-type conductivity doped with copper and bismuth obtained by hot pressing of three types powders prepared by grinding an ingot to a size of hundreds microns (0.315  mm) to hundreds of nanometers (mechanical activation) in planetary high-energy mill and melt spinning were investigated. The microstructure of the samples were analyzed by optical and electron scanning microscopies. The nanoscale grain structure of these samples was established. The thermoelectric characteristics of the materials: Seebeck coefficient, electrical and thermal conductivities, were measured both at room temperature and in the temperature range of 100 – 800 K. The slopes of these dependencies are estimated. The coefficient of thermoelectric figure of merit is calculated. The higher thermoelectric efficiency (ZT = 1.5 at 600 K) was received for the samples hot-pressed from granules, prepared by melt spinning.

Significantly enhanced thermoelectric figure of merit of p-type Mg3Sb2-based Zintl phase compounds via nanostructuring and employing high energy mechanical milling coupled with spark plasma sintering

2015 ◽  
Vol 3 (20) ◽  
pp. 10777-10786 ◽  
Author(s):  
A. Bhardwaj ◽  
N. S. Chauhan ◽  
D. K. Misra
Keyword(s):  
Thermoelectric Materials ◽  
Mechanical Milling ◽  
Figure Of Merit ◽  
High Energy ◽  
Thermoelectric Figure Of Merit ◽  
Zintl Phase ◽  
Thermoelectric Figure ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
P Type

Several nanostructuring methods have been demonstrated to produce a variety of nanostructured materials, and these methods are well recognized as effective paradigms for improving the performance of thermoelectric materials.

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.

Enhanced Thermoelectric Figure-of-merit at Room Temperature in Bulk Bi(Sb)Te(Se) With Grain Size of ∼100nm

2013 ◽  
Vol 1543 ◽  
pp. 93-98 ◽  
Author(s):  
Tsung-ta E. Chan ◽  
Rama Venkatasubramanian ◽  
James M. LeBeau ◽  
Peter Thomas ◽  
Judy Stuart ◽  
...  
Keyword(s):  
Grain Size ◽  
Mechanical Alloying ◽  
Grain Boundaries ◽  
Figure Of Merit ◽  
Room Temperature ◽  
High Energy ◽  
High Density ◽  
Nanocrystalline Powders ◽  
Bulk Materials ◽  
P Type

ABSTRACTGrain boundaries are known to be able to impede phonon transport in the material. In the thermoelectric application, this phenomenon could help improve the figure-of-merit (ZT) and enhance the thermal to electrical conversion. Bi2Te3 based alloys are renowned for their high ZT around room temperature but still need improvements, in both n- and p-type materials, for the resulting power generation devices to be more competitive. To implement high density of grain boundaries into the bulk materials, a bottom-up approach is employed in this work: consolidations of nanocrystalline powders into bulk disks. Nanocrystalline powders are developed by high energy cryogenic mechanical alloying that produces Bi(Sb)Te(Se) alloy powders with grain size in the range of 7 to 14 nm, which is about 25% finer compared to room temperature mechanical alloying. High density of grain boundaries are preserved from the powders to the bulk materials through optimized high pressure hot pressing. The consolidated bulk materials have been characterized by X-ray diffraction and transmission electron microscope for their composition and microstructure. They mainly consist of grains in the scale of 100 nm with some distributions of finer grains in both types of materials. Preliminary transport property measurements show that the thermal conductivity is significantly reduced at and around room temperature: about 0.65 W/m-K for the n-type BiTe(Se) and 0.85 W/m-K for the p-type Bi(Sb)Te, which are attributed to increased phonon scattering provided by the nanostructure and therefore enhanced ZT about 1.35 for the n-type and 1.21 for the p-type are observed. Detailed transport properties, such as the electrical resistivity, Seebeck coefficient and power factor as well as the resulting ZT as a function of temperature will be described.

Thermoelectric Properties of P-Type (Bi1−xSbx)2Te3 Fabricated by Mechanical Alloying Process

1997 ◽  
Vol 478 ◽  
Author(s):  
Boo Yang Jung ◽  
Jae Shik Choi ◽  
Tae Sung Oh ◽  
Dow-Bin Hyun
Keyword(s):  
Mechanical Alloying ◽  
Thermoelectric Properties ◽  
Hot Pressing ◽  
Alloy Powder ◽  
Figure Of Merit ◽  
Processing Time ◽  
Pressing Temperature ◽  
Acceptor Dopant ◽  
Maximum Value ◽  
P Type

AbstractThermoelectric properties of polycrystalline (Bi1−xSbx)2Te3 (0.75 ≤ x ≤ 0.85), fabricated by mechanical alloying and hot pressing methods, have been investigated. Formation of (Bi0.25Sb0.75)2Te3 alloy powder was completed by mechanical alloying for 5 hours at ball- to-material ratio of 5: 1, and processing time for (Bi1−xSbx)2Te3 formation increased with Sb2Te3 content x. When (Bi0.25Sb0.75)2Te3 was hot pressed at temperatures ranging from 300°C to 550°C for 30 minutes, figure-of-merit increased with hot pressing temperature and maximum value of 2.8 × 10−3/K could be obtained by hot pressing at 550°C. When hot pressed at 550°C, (Bi0.2Sb0.8)2Te3 exhibited figure-of-merit of 2.92 × 10−3/K, which could be improved to 2.97 × 10−3/K with addition of 1 wt% Sb as acceptor dopant.

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