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.

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.

Enhanced Thermoelectric Properties of Mg2Si0.3Sn0.7 Compounds by Bi Doping

2014 ◽  
Vol 616 ◽  
pp. 174-177
Author(s):  
Mei Jun Yang ◽  
Qiang Shen ◽  
Lian Meng Zhang
Keyword(s):  
Thermal Conductivity ◽  
Thermoelectric Properties ◽  
Figure Of Merit ◽  
Doping Concentration ◽  
Single Phase ◽  
Doping Content ◽  
Maximum Value ◽  
Plasma Sintering ◽  
Bi Doping ◽  
Spark Plasma

The single phase of Bi-doped Mg2Si0.3Sn0.7compounds have been successfully fabricated by solid state reaction and spark plasma sintering (SPS). The effect of Bi doping concentration on the thermoelectric properties of Mg2Si0.3Sn0.7is investigated. The doping of Bi atom results in the increase of carrier concentrations and ensures the increase of electrical conductivity. Although the thermal conductivity and Seebeck coefficient shows a slight increase, the figure of merit of Mg2Si0.3Sn0.7compounds still increases with the increasing contents of Bi-doping. When Bi-doping content is 1.5at%, the Mg2Si0.3Sn0.7compound obtained the maximum value,ZT, is 1.03 at 640 K.

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.

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].

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.

Thermoelectric properties of Cu2Se/xNi0.85Se hot-pressed from hydrothermal synthesis nanopowders

2017 ◽  
Vol 31 (09) ◽  
pp. 1750093 ◽  
Author(s):  
Feng Gao ◽  
Xiaohan Du ◽  
Fang Wu ◽  
Xinjian Li ◽  
Xing Hu ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Electrical Resistivity ◽  
Hydrothermal Synthesis ◽  
Hydrothermal Method ◽  
Thermoelectric Properties ◽  
Figure Of Merit ◽  
Secondary Phase ◽  
Seebeck Coefficients ◽  
Maximum Value ◽  
Bulk Alloys

The [Formula: see text] ([Formula: see text] = 0, 0.025, 0.05, 0.075, 0.1, 0.15, 0.2, 0.3, 0.4 and 0.5) nanopowders were synthesized by the hydrothermal method and then were hot-pressed into bulk alloys. The effects of [Formula: see text] secondary phase on the thermoelectric (TE) properties of [Formula: see text] were investigated. For [Formula: see text] and [Formula: see text], both their electrical resistivity and Seebeck coefficients increase. While for [Formula: see text], they decrease instead. The samples for [Formula: see text] have lower thermal conductivity. However, for [Formula: see text], the thermal conductivity rises remarkably. As an overall result, the maximum value of dimensionless TE figure of merit (ZT) reaches 1.52 at 873 K for the sample of [Formula: see text], 36.5% higher than for the sample without [Formula: see text].

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.

scholarly journals Thermoelectric properties of Ni0.15Co3.85Sb12 and Fe0.2Ni0.15Co3.65Sb12 skutterudites prepared by HPHT method

2017 ◽  
Vol 35 (3) ◽  
pp. 496-500 ◽  
Author(s):  
Lingjiao Kong ◽  
Hongan Ma ◽  
Yuewen Zhang ◽  
Xin Guo ◽  
Bing Sun ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Thermal Conductivity ◽  
High Pressure ◽  
High Temperature ◽  
Transport Properties ◽  
Thermoelectric Properties ◽  
Figure Of Merit ◽  
Thermoelectric Figure Of Merit ◽  
Thermoelectric Figure ◽  
Synthesis Time

AbstractN-type polycrystalline skutterudite compounds Ni0.15Co3.85Sb12 and Fe0.2Ni0.15Co3.65Sb12 with the bcc crystal structure were synthesized by high pressure and high temperature (HPHT) method. The synthesis time was sharply reduced to approximately half an hour. Typical microstructures connected with lattice deformations and dislocations were incorporated in the samples of Ni0.15Co3.85Sb12 and Fe0.2Ni0.15Co3.65Sb12 after HPHT. Electrical and thermal transport properties were meticulously researched in the temperature range of 300 K to 700 K. The Fe0.2Ni0.15Co3.65Sb12 sample shows a lower thermal conductivity than that of Ni0.15Co3.85Sb12. The dimensionless thermoelectric figure-of-merit (zT) reaches the maximal values of 0.52 and 0.35 at 600 K and 700 K respectively, for Ni0.15Co3.85Sb12 and Fe0.2Ni0.15Co3.65Sb12 samples synthesized at 1 GPa.

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 Two Ternary Tellurides

1998 ◽  
Vol 545 ◽  
Author(s):  
Jeff W. Sharp ◽  
Brian C. Sales ◽  
David G. Mandrus ◽  
Bryan C. Chakoumakos
Keyword(s):  
Thermal Conductivity ◽  
Thermoelectric Properties ◽  
Figure Of Merit ◽  
Lattice Thermal Conductivity ◽  
Atomic Displacement ◽  
Thermal Expansion Coefficients ◽  
Good Figure ◽  
Atomic Displacement Parameters ◽  
Binary Compounds ◽  
P Type

AbstractWe present initial assessments of the thermoelectric properties of two ternary tellurides with known crystal structures, Tl2GeTeM5 and Tl2SnTe5. Tl2SnTe5 appears to have a p-type figure of merit about the same as that of Bi2Te3, the best thermoelectric material among binary compounds. A good figure of merit is possible because the lattice thermal conductivity is very low. Based on neutron diffraction data, we have calculated atomic displacement parameters and thermal expansion coefficients. The atomic displacement parameters give some understanding of the low lattice thermal conductivity.

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