Thermoelectric Properties of Undoped CoSb3

2004 ◽  
Vol 449-452 ◽  
pp. 917-920 ◽  
Author(s):  
Il Ho Kim ◽  
G.S. Choi ◽  
M.G. Han ◽  
Ji Soon Kim ◽  
Jung Il Lee ◽  
...  
Keyword(s):  
Phase Transformation ◽  
Phase Transitions ◽  
Thermoelectric Properties ◽  
Single Phase ◽  
Arc Melting ◽  
Annealing Effects ◽  
P Type ◽  
Type Conduction ◽  
Semiconducting Behavior

CoSb3 compounds were prepared by the arc melting and their thermoelectric properties were investigated at 300K-600K. Annealing effects were examined and they were correlated to phase transformation and homogenization. Undoped CoSb3 showed p-type conduction and intrinsic semiconducting behavior at all temperatures examined. Thermoelectric properties were changed with constituent phases because α-CoSb2, β-CoSb and Sb are metallic or semimetallic phases while δ-CoSb3 is semiconducting phase. Thermoelectric properties were remarkably improved by annealing in vacuum and they were closely related to phase transitions. Single phase δ-CoSb3 was successfully obtained by annealing at 400°C for 24hrs.

Annealing Effect on the Thermoelectric Properties of Undoped CoSb3

2006 ◽  
Vol 118 ◽  
pp. 565-570 ◽  
Author(s):  
Il Ho Kim ◽  
Jung Il Lee ◽  
Soon Chul Ur ◽  
Kyung Wook Jang ◽  
Good Sun Choi ◽  
...  
Keyword(s):  
Phase Transformation ◽  
Phase Transitions ◽  
Thermoelectric Properties ◽  
Hot Pressing ◽  
Annealing Effect ◽  
Metallic Behavior ◽  
Arc Melting ◽  
P Type ◽  
Type Conduction

Binary skutterudite CoSb3 compounds were prepared by the arc melting and hot pressing processes and their thermoelectric properties were investigated at 300K-600K. Annealing effect was examined and it was correlated to phase transformation and homogenization. Thermoelectric properties of the arc-melted and hot-pressed CoSb3 were discussed and compared. Undoped CoSb3 prepared by the arc melting showed p-type conduction and metallic behavior at all temperatures examined. However, hot pressed specimens showed n-type conduction, possibly due to Sb evaporation. Thermoelectric properties were remarkably improved by annealing in vacuum and they were closely related to phase transitions.

Effects of Annealing Treatment on Microstructure and Thermoelectric Properties of Ba8Al16Si30

2006 ◽  
Vol 118 ◽  
pp. 561-564 ◽  
Author(s):  
Jung Il Lee ◽  
Jong Bum Park ◽  
Sin Wook You ◽  
Joo Ho Lee ◽  
Il Ho Kim ◽  
...  
Keyword(s):  
Thermoelectric Properties ◽  
Isothermal Annealing ◽  
Annealing Treatment ◽  
Hardness Test ◽  
X Ray Diffraction ◽  
Transformation Behavior ◽  
Scanning Calorimetry ◽  
Arc Melting ◽  
Annealing Effects ◽  
Type Conduction

Clathrate Ba8Al16Si30 was produced by arc melting and annealing effects on the microstructure and thermoelectric properties were investigated. The phase transformation behavior of arc-melted Ba8Al16Si30 was examined by thermogravimetric analysis, differential scanning calorimetry, hardness test, X-ray diffraction and scanning electron microscope analyses. Isothermal annealing was carried out to induce the transformation to a thermoelectric phase at 500°C to 700°C for 5 hrs. Thermoelectric properties in the temperature range between 300K and 600K were measured and evaluated. Electrical conductivity was decreased and Seebeck coefficient was increased with increasing isothermal annealing temperature. The arc-melted and the isothermal annealed specimens represented n-type conduction at temperatures examined, and they showed reliable thermoelectric behaviors.

Thermoelectric Properties of Ru2Si3-Based Chimney-Ladder Phases

2007 ◽  
Vol 561-565 ◽  
pp. 463-466 ◽  
Author(s):  
Kyosuke Kishida ◽  
Akira Ishida ◽  
Katsushi Tanaka ◽  
Haruyuki Inui
Keyword(s):  
Crystal Structures ◽  
Thermoelectric Properties ◽  
Electron Concentration ◽  
Valence Electron ◽  
Valence Electron Concentration ◽  
Compositional Range ◽  
Wide Compositional Range ◽  
P Type ◽  
Semiconducting Behavior

The variations of the crystal structures and thermoelectric properties of the Ru1-xRexSiy chimney-ladder phases were studied as a function of the Re concentration. A series of chimney-ladder phases with a compositional formula of Ru1-xRexSi1.539+0.178x are formed in a wide compositional range, 0.14 ≤ x ≤ 0.76. The composition of the chimney-ladder phase is systematically deviated from the idealized composition satisfying the valence electron concentration rule: VEC=14. Measurements of thermoelectric properties reveal that the chimney-ladder phases exhibit n-type semiconducting behavior at low Re concentrations and p-type semiconducting behavior at high Re concentrations, which are well consistent with the prediction based on the deviation of the composition of the chimney-ladder phase from the idealized composition.

Annealing Effects on Powder Metallurgy Based Pb1-xSnxTe Materials for Thermoelectric Applications

2007 ◽  
Vol 336-338 ◽  
pp. 860-863
Author(s):  
Y. Gelbstein ◽  
Z. Dashevsky ◽  
R. Kreizman ◽  
Y. George ◽  
M. Gelbstein ◽  
...  
Keyword(s):  
Powder Metallurgy ◽  
Thermoelectric Properties ◽  
Annealing Treatment ◽  
Preparation Technique ◽  
Tin Telluride ◽  
Powder Metallurgy Process ◽  
Lead Tin Telluride ◽  
Annealing Effects ◽  
P Type ◽  
Metallurgy Process

Lead tin telluride based alloys are known p-type materials for thermoelectric applications, in the 50-600oC temperature range. These alloys combine desired features of mechanical and thermoelectric properties. The electronic transport properties of PbTe and Pb1-xSnxTe materials may be strongly dependent on the preparation technique. Powder metallurgy process is known to introduce defects and strains, that may alter carrier concentration. Under such non-equilibrium conditions the thermoelectric properties are instable at the operating temperature. An appropriate annealing treatment can eliminate this effect.. The present communication describes the annealing treatment applied to cold compacted and sintered Pb1-xSnxTe materials.

scholarly journals Study on Enhancing the Thermoelectric Properties of Ti2CrSn Alloys

Metals ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 1503
Author(s):  
Guangfa Yu ◽  
Shihao Song ◽  
Yanwei Ren ◽  
Jia Guo ◽  
Liqin Yan ◽  
...  
Keyword(s):  
Thermoelectric Properties ◽  
Ground State Band ◽  
Arc Melting ◽  
Maximum Value ◽  
Potential Applications ◽  
State Band ◽  
Elemental Doping ◽  
Microscopic Morphology ◽  
P Type ◽  
Full Heusler

Based on the Hg2CuTi structure, the full-Heusler alloy Ti2CrSn, with a ground state band gap of semiconductor, is a thermoelectric material with potential applications. Through preparing Ti2CrSn1−xAlx (x = 0, 0.05, 0.1, 0.15, 0.2) series bulk materials via arc melting, the effects of the electrical and thermal transport properties of Ti2CrSn series alloys were investigated, and different Al doping on the phase structure, the microscopic morphology, and the thermoelectric properties of Ti2CrSn were examined. The results show that the materials all exhibit characteristics of p-type semiconductors at the temperature range of 323 to 923 K. Al elemental doping can significantly increase the Seebeck coefficient and reduce the thermal conductivity of the materials. Among them, the sample Ti2CrSn0.8Al0.2 obtained a maximum value of 5.03 × 10−3 for the thermoelectric optimal ZT value at 723 K, which is 3.6 times higher than that of Ti2CrSn.

Microstructure and Thermoelectric Properties of CoSb3 Synthesized by MA-SPS Method

2007 ◽  
Vol 336-338 ◽  
pp. 834-837 ◽  
Author(s):  
Wei Shu Liu ◽  
Bo Ping Zhang ◽  
Jing Feng Li ◽  
Heng Wang
Keyword(s):  
Grain Size ◽  
Thermoelectric Properties ◽  
Room Temperature ◽  
Single Phase ◽  
New Combination ◽  
Plasma Sintering ◽  
Average Grain Size ◽  
Spark Plasma ◽  
Xrd Patterns ◽  
Type Conduction

Single-phase polycrystalline CoSb3 skutterudite was prepared through a new combination of mechanical alloying (MA) and spark plasma sintering (SPS). In order to investigate the influence of MA conditions on the microstructure and thermoelectric properties, MA synthesis were carried out under various conditions with different milling times. The powder sample MAed for 6h still consisted of metal Sb, and then transformed to CoSb3 with a little amount of metal Sb and CoSb2 phases after MA for 15h. Further prolonging the MA time resulted in the decomposition of CoSb3 to CoSb2 phase. The average grain size of the SPSed samples decreased from 650nm to 250nm as MA-time was prolonged from 6 to 24h. Lattice parameters estimated form XRD patterns increase with the increasing MA time. All samples SPSed at 600°C for holding 5 min show an n-type conduction. The electrical resistivity was 1030, 895, 410, 260 μm for the samples from the MA-derived powders with MA-time of 6, 15, 24 and 33h at room temperature, respectively, then reduced to 60 μm at 400°C for all samples. An optimum MA time is 24 h in which the sample shows the highest power factor 612μW/m*K2 at 150°C.

Synthesis and thermoelectric properties of p-type barium-filled skutterudite BayFexCo4−xSb12

2002 ◽  
Vol 17 (11) ◽  
pp. 2953-2959 ◽  
Author(s):  
X. F. Tang ◽  
L. D. Chen ◽  
T. Goto ◽  
T. Hirai ◽  
R. Z. Yuan
Keyword(s):  
Single Phase ◽  
Lattice Thermal Conductivity ◽  
Composition Range ◽  
Solid State Reaction Method ◽  
Filling Fraction ◽  
Filled Skutterudite ◽  
Reaction Method ◽  
Fe Content ◽  
P Type ◽  
Type Conduction

Single-phase barium-filled skutterudite compounds, BayFexCo4−xSb12 (x = 0 to 3.0, y = 0 to 0.7), were synthesized by a two-step solid-state reaction method. The maximum filling fraction of Ba (ymax) in BayFexCo4–xSb12 increased with increasing Fe content and was found to be rather greater than that of CeyFexCo4–xSb12. The ymax varied from 0.35 to near 1.0 when Fe content changed from 0 to 4.0. BayFexCo4–xSb12 showed p-type conduction at a composition range of x = 0 to 3.0, y = 0 to 0.7. Carrier concentration and electrical conductivity increased with increasing Fe content and decreased with increasing Ba filling fraction. The Seebeck coefficient increased with increasing Ba filling fraction and with decreasing Fe content. Lattice thermal conductivity decreased with increasing Ba filling fraction and reached a minimum at a certain Ba filling fraction (y = 0.3 to 0.4). The greatest ZT value of 0.9 was obtained at 750 K for p-type Ba0.27Fe0.98Co3.02Sb12. It is expected that further investigation on the optimization of filling fraction would result in a higher ZT value at the moderately low Fe content region.

Investigation of the thermoelectric properties of the PbTe-SrTe system

2010 ◽  
Vol 1267 ◽  
Author(s):  
Kanishka Biswas ◽  
Jiaqing He ◽  
Qichun Zhang ◽  
Guoyu Wang ◽  
Ctirad Uher ◽  
...  
Keyword(s):  
Thermoelectric Properties ◽  
Secondary Phase ◽  
Positive Sign ◽  
X Ray Diffraction ◽  
Rock Salt Structure ◽  
High Power Factor ◽  
Salt Structure ◽  
Diffraction Patterns ◽  
P Type ◽  
Type Conduction

AbstractPbTe-based materials are promising for efficient heat energy to electricity conversion. We present studies of the thermoelectric properties of the PbTe-SrTe system. X-ray diffraction patterns reveal that all the samples crystallize in the rock salt structure without noticeable secondary phase. Na2Te doping of the PbTe-SrTe materials resulting in a positive sign Hall coefficient indicating p-type conduction. Lattice thermal conductivity is significantly decreased with the insertion of SrTe in PbTe lattice. The ZT ∼ 1.3 of these materials is derived from their very low thermal conductivities and reasonably high power factor at 800 K.

Thermoelectric Properties of Tl2Te-Sb2Te3 Pseudo-Binary System

2005 ◽  
Vol 886 ◽  
Author(s):  
Ken Kurisaki ◽  
Keita Goto ◽  
Atsuko Kosuga ◽  
Hiroaki Muta ◽  
Shinsuke Yamanaka
Keyword(s):  
Thermal Conductivity ◽  
Binary System ◽  
Thermoelectric Properties ◽  
Room Temperature ◽  
State Of The Art ◽  
Electrical Performance ◽  
Low Thermal Conductivity ◽  
Maximum Value ◽  
P Type ◽  
Type Conduction

ABSTRACTPolycrystalline-sintered samples of thallium based substances, (Tl2Te)100−x(Sb2Te3)x (x= 0, 1, 5, 10), were prepared by melting Tl2Te and Sb2Te3 ingots followed by annealing in sealed quartz ampoules. The thermoelectric properties were measured from room temperature to around 600 K. The values of the Seebeck coefficient of all samples are positive, indicating a p-type conduction characteristic. The maximum value of the power factor is 6.53×10−4 Wm−1K−2 at 591 K obtained for x= 10 (Tl9SbTe6), which is about one order lower than those of state-of-the-art thermoelectric materials. All samples indicate an extremely low thermal conductivity, for example that of Tl2Te is approximately 0.35 Wm−1K−1 from room temperature to around 600 K. Although the electrical performance of the samples is not so good, the ZT value is relatively high due to the extremely low thermal conductivity. The maximum ZT value is 0.42 at 591 K obtained for Tl9SbTe6.

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