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.

Thermoelectric Properties of N-Type Bi2(Tel−xSex)3 Fabricated by Mechanical Alloying and Hot Pressing

1997 ◽  
Vol 478 ◽  
Author(s):  
Hee-Jeong Kim ◽  
Jae-Shik Choi ◽  
Tae-Sung Oh ◽  
Dow-Bin Hyun
Keyword(s):  
Mechanical Alloying ◽  
Thermoelectric Properties ◽  
Hot Pressing ◽  
Figure Of Merit ◽  
Processing Time ◽  
Acceptor Dopant ◽  
Maximum Value

AbstractThermoelectric properties of polycrystalline Bi2(Te1−xSex)3 (0.05 ≤ x ≤ 0.25), fabricated by mechanical alloying and hot pressing, have been investigated. Formation of n-type Bi2(Te0.9 Se0.1)3 alloy powders was completed by mechanical alloying for 3 hours at ball-to-material ratio of 5: 1, and processing time for Bi2(Te1−xSex)3 formation increased with Bi2Se3 content x. Figure-of-merit of Bi2(Te0.9Se0.1) was markedly increased by hot pressing at temperatures above 450°C, and maximum value of 1.9 × 10−3/K was obtained by hot pressing at 550°C. With addition of 0.015 wt% Bi as acceptor dopant, figure-of-merit of Bi2 (Te0.9Se0.1)3, hot pressed at 550°C, could be improved to 2.1 × 10−3/K. When Bi2(Te1−xSex)3 was hot pressed at 550°C, figure-of-merit increased from 1.14 × 103/K to 1.92 × 10−3/K with increasing Bi2Se3 content x from 0.05 to 0.15, and then decreased to 1.30 × 103/K for x = 0.25 composition.

Microstructural and Thermoelectric Properties of P-Type Te–Doped Bi0.5Sb1.5Te3 And N-Type SbI3-Doped Bi2Te2.85Se0.15 Compounds

1997 ◽  
Vol 478 ◽  
Author(s):  
J. Seo ◽  
K. Park ◽  
C. Lee ◽  
J. Kim
Keyword(s):  
Thermoelectric Properties ◽  
Hot Pressing ◽  
Figure Of Merit ◽  
Crystalline Quality ◽  
Fracture Path ◽  
Pressing Temperature ◽  
High Crystalline Quality ◽  
Transgranular Cleavage ◽  
Temperature Range ◽  
P Type

AbstractThe p-type Te-doped Bi0.5Sb1.5Te3 and n-type SbI3-doped Bi2Te2.85Se0.15 thermoelectric compounds were fabricated by hot pressing in the temperature range of 380 to 440 °C under 200 MPa in Ar. Both the compounds were highly dense and showed high crystalline quality. The grains of the compounds were preferentially oriented and contained many dislocations through the hot pressing. The fracture path followed the transgranular cleavage planes, which are perpendicular to the c-axis. In addition, with increasing the pressing temperature, the figure of merit was increased. The highest values of figure of merit for the p- and n-type compounds, which were obtained at 420 °C, were 2.69 × 10−3/K and 2.35×10−3/K, respectively.

scholarly journals Thermoelectric Properties of Nano/microstructured p-Type Bi0.4Sb1.6Te3 Powders Fabricated by Mechanical Alloying and Vacuum Hot Pressing

2013 ◽  
Vol 43 (6) ◽  
pp. 1718-1725 ◽  
Author(s):  
Pee-Yew Lee ◽  
Joey Hao ◽  
Tz-Yuan Chao ◽  
Jing-Yi Huang ◽  
Huey-Lin Hsieh ◽  
...  
Keyword(s):  
Mechanical Alloying ◽  
Thermoelectric Properties ◽  
Hot Pressing ◽  
Vacuum Hot Pressing ◽  
P Type

Thermoelectric Properties of Nanostructured CoSb3 Synthesized by Mechanical Alloying

2007 ◽  
Vol 534-536 ◽  
pp. 1425-1428
Author(s):  
Soon Chul Ur ◽  
Joon Chul Kwon ◽  
Moon Kwan Choi ◽  
Soon Young Kweon ◽  
Tae Whan Hong ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Mechanical Alloying ◽  
Thermoelectric Properties ◽  
Hot Pressing ◽  
Figure Of Merit ◽  
Single Phase ◽  
Phonon Scattering ◽  
Stoichiometric Composition ◽  
Processing Route ◽  
Vacuum Hot Pressing

Undoped CoSb3 powders were synthesized by mechanical alloying of elemental powders using a nominal stoichiometric composition. Nanostructured, single-phase skutterudite CoSb3 was successfully produced by vacuum hot pressing using as-milled powders without subsequent annealing. Phase transformations during synthesis were investigated using XRD, and microstructure was observed using SEM and TEM. Thermoelectric properties in terms of Seebeck coefficient, electrical conductivity, thermal conductivity and figure of merit were systematically measured and compared with the results of analogous studies. Lattice thermal conductivity was reduced owing to increasing phonon scattering in nanostructured CoSb3, leading to enhancement in the thermoelectric figure of merit. Mechanical Alloying associated with vacuum hot pressing technique offers an alternative potential processing route for the production of skutterudites.

Enhanced thermoelectric properties of the hole-doped Bi2−xKxSr2Co2Oy ceramics

2015 ◽  
Vol 29 (28) ◽  
pp. 1550192 ◽  
Author(s):  
Feng Gao ◽  
Qinglin He ◽  
Ruijuan Cao ◽  
Fang Wu ◽  
Xing Hu ◽  
...  
Keyword(s):  
Electrical Resistivity ◽  
Thermoelectric Properties ◽  
Figure Of Merit ◽  
Solid State Reaction Method ◽  
Undoped Sample ◽  
Seebeck Coefficients ◽  
Maximum Value ◽  
Element Doping ◽  
P Type ◽  
Remarkable Reduction

In this paper, the influence of K element doping on the thermoelectric properties of the [Formula: see text] (x = 0.00, 0.05, 0.10, 0.15, and 0.20) samples prepared by the solid-state reaction method were investigated from 333 K to 973 K. It was shown that due to the p-type K doping the electrical resistivity of the doped sample can be reduced remarkably as compared with the undoped sample, especially for the optimum doped sample [Formula: see text]. The Seebeck coefficients of the K doped samples have only a slight decrease as compared with the undoped sample. As a result of the remarkable reduction of the electrical resistivity the power factor of the doped sample have a significant improvement. The thermal conductivity of the samples is depressed due to the defects caused by K doping. As an overall result, the dimensionless figure of merit (ZT) of the [Formula: see text] sample reaches a maximum value of 0.3 at 973 K, being 93% higher than that of the undoped sample.

Thermoelectric properties of Ru and In substituted misfit-layered Ca3Co4O9

2013 ◽  
Vol 1543 ◽  
pp. 83-92 ◽  
Author(s):  
Gesine Saucke ◽  
Sascha Populoh ◽  
Nina Vogel-Schäuble ◽  
Leyre Sagarna ◽  
Kailash Mogare ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Thermal Conductivity ◽  
Thermoelectric Properties ◽  
Low Temperatures ◽  
Figure Of Merit ◽  
Reaction Route ◽  
Promising Strategy ◽  
Maximum Value ◽  
Solid State Reaction Route ◽  
P Type

ABSTRACTAs an approach to improve the thermoelectric properties of the polycrystalline Ca3Co4O9 misfit-layered oxide, substitutions of Co2+…4+ with the heavier cations Ru3+/4+ and In3+ were tested. Polycrystalline samples Ca3Co4-xRuxO9 and Ca3Co4-xInxO9 (0 < x < 0.21) were prepared via a solid-state-reaction route. For each sample the crystal structure was analyzed and a complete thermoelectric characterization was done within a temperature range of 300 K < T < 1125 K.Both substitution strategies resulted in a significant decrease of the thermal conductivity (κ). For the In3+-substituted samples the decrease of the Seebeck coefficient (α) balanced the κ reduction so that no overall enhancement of the figure of merit (ZT) was found. The Ru3+/4+ substitution reduced the p-type carrier concentration and thus increases the electrical resistivity (ρel), while α became larger at low temperatures. Despite the reduction of the power factor, a small enhancement in ZT was observed in the case of x = 0.1 Ru substitution, due to the strong κ reduction. Considering the observed preferred orientation of the Ru-substituted crystallites, a maximum value of ZT = 0.14 perpendicular to the pressing direction is found at T = 1125 K, indicating that Ru substitution is a promising strategy for a further ZT improvement.

Effect of Fe Doping on Thermoelectric Properties of Mechanically Alloyed CoSb3

2007 ◽  
Vol 534-536 ◽  
pp. 177-180
Author(s):  
Soon Chul Ur ◽  
Joon Chul Kwon ◽  
Il Ho Kim
Keyword(s):  
Mechanical Alloying ◽  
Thermoelectric Properties ◽  
Hot Pressing ◽  
Figure Of Merit ◽  
Solubility Limit ◽  
Nominal Composition ◽  
Second Phase ◽  
Fe Doping ◽  
Mechanically Alloyed ◽  
Vacuum Hot Pressing

Fe doped skutterudite CoSb3 with a nominal composition of FexCo1-xSb12 (0≤x≤2.5) have been synthesized by mechanical alloying (MA) of elemental powders, followed by vacuum hot pressing. Phase transformations during mechanical alloying and vacuum hot pressing were systematically investigated using XRD. Single phase skutterudite was successfully produced by vacuum hot pressing using as-milled powders without subsequent annealing. However, second phase in the form of marcasite structure FeSb2 was found to exist in case of x≥2, suggesting the solubility limit of Fe with Co in this system. Thermoelectric properties as functions of temperature and Fe contents were evaluated for the hot pressed specimens. Fe doping up to x=1.5 with Co in FexCo4-xSb12 appeared to increase thermoelectric figure of merit (ZT) and the maximum ZT was found to be 0.78 at 525K in this study.

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