Large thermopower in metallic misfit cobalt oxides : improvement by cationic substitutions

2001 ◽  
Vol 691 ◽  
Author(s):  
S. Hébert ◽  
L. B. Wang ◽  
A. Maignan ◽  
D. Pelloquin ◽  
M. Hervieu ◽  
...  
Keyword(s):  
Thermoelectric Properties ◽  
Rock Salt ◽  
Figure Of Merit ◽  
Partial Substitution ◽  
Crystallographic Structure ◽  
Cobalt Oxides ◽  
New Family ◽  
Edge Shared Octahedra

ABSTRACTThe thermoelectric properties of misfit cobaltites have been investigated. Their crystallographic structure consists in the stacking of layers of tilted CoO6 edge-shared octahedra, separated by rock-salt type layers. The Tl based family was first investigated : it is shown that by increasing the Tl content, the resistivity ρ can be reduced while keeping a large thermopower S. Another way to improve the figure of merit Z=S2/(ρκ) is to partially substitute Bi for Tl to increase S and keep a small ρ. A new family of Pb-based misfits has also been investigated. Two different techniques have been attempted to decrease ρ and/or increase S in this family : the partial substitution of Cu for Co, and the partial substitution of Ca for Sr.

Improvement in thermoelectric properties of (ZnO)5In2O3 through partial substitution of yttrium for indium

1998 ◽  
Vol 13 (3) ◽  
pp. 523-526 ◽  
Author(s):  
Masaki Kazeoka ◽  
Hidenori Hiramatsu ◽  
Won-Seon Seo ◽  
Kunihito Koumoto
Keyword(s):  
Thermoelectric Properties ◽  
Figure Of Merit ◽  
Lattice Structure ◽  
Partial Substitution ◽  
Unusual Behavior ◽  
Thermoelectric Figure ◽  
Hexagonal System ◽  
Thermoelectric Energy ◽  
Homologous Compounds ◽  
Y Substitution

We first measured the thermoelectric properties of layer-structured homologous compounds, (ZnO)mIn2O3 (m = integer), and reported that they would becomecandidate materials for high-temperature thermoelectric energy conversion.1–4 We further tried to improve their thermoelectric properties by partially substituting yttrium for indium in (ZnO)5In2O3. Though the ionic radius of Y3+ is larger than that of In3+, the a-axis (hexagonal system) elongated and c-axis shrank as Y was substituted for In. The thermoelectric properties were found to vary with a varying amount of Y substitution; 3% Y substitution gave rise to the largest thermoelectric figure of merit, i.e., 1.1 - 1.3 × 10-4 K-1 at 960–1100 K. The abnormal change in the lattice structure by Y substitution was responsible for the unusual behavior of the thermoelectric properties.

Influence of multi-sintering on the thermoelectric properties of Bi2Sr2Co2Oy ceramics

2019 ◽  
Vol 34 (02) ◽  
pp. 2050019 ◽  
Author(s):  
Y. Zhang ◽  
M. M. Fan ◽  
C. C. Ruan ◽  
Y. W. Zhang ◽  
X.-J. Li ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Thermoelectric Properties ◽  
Figure Of Merit ◽  
Phonon Scattering ◽  
Sintered Sample ◽  
Thermoelectric Figure Of Merit ◽  
Thermoelectric Figure ◽  
The Third ◽  
Ceramic Samples ◽  
Optimum Formula

[Formula: see text] ceramic samples have a structure similar to phonon glass electronic crystals, and their thermoelectric properties can be effectively adjusted through repeated grinding and sintering. The results show that multi-sintering can make their grain refined and increase their grain boundary, which will effectively increase density and phonon scattering. Finally, multi-sintering can reduce the resistivity and thermal conductivity, thus obviously improve thermoelectric figure of merit [Formula: see text] of [Formula: see text]. The optimum [Formula: see text] value of 0.26 is achieved at 923 K by the third sintered sample.

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.

Effects of Ce filling fraction and Fe content on the thermoelectric properties of Co-rich CeyFexCo4−xSb12

2001 ◽  
Vol 16 (3) ◽  
pp. 837-843 ◽  
Author(s):  
Xinfeng Tang ◽  
Lidong Chen ◽  
Takashi Goto ◽  
Toshio Hirai
Keyword(s):  
Thermal Conductivity ◽  
Thermoelectric Properties ◽  
Figure Of Merit ◽  
Single Phase ◽  
Lattice Thermal Conductivity ◽  
Hole Concentration ◽  
Thermoelectric Figure Of Merit ◽  
Thermoelectric Figure ◽  
Filling Fraction ◽  
Fe Content

Single-phase filled skutterudite compounds, CeyFexCo4−xSb12 (x = 0 to 3.0, y = 0 to 0.74), were synthesized by a melting method. The effects of Fe content and Ce filling fraction on the thermoelectric properties of CeyFexCo4−xSb12 were investigated. The lattice thermal conductivity of Ce-saturated CeyFexCo4−xSb12, y being at the maximum corresponding to x, decreased with increasing Fe content (x) and reached its minimum at about x = 1.5. When x was 1.5, lattice thermal conductivity decreased with increasing Ce filling fraction till y = 0.3 and then began to increase after reaching the minimum at y = 0.3. Hole concentration and electrical conductivity of Cey Fe1.5Co2.5Sb12 decreased with increasing Ce filling fraction. The Seebeck coefficient increased with increasing Ce filling fraction. The greatest dimensionless thermoelectric figure of merit T value of 1.1 was obtained at 750 K for the composition of Ce0.28Fe1.52Co2.48Sb12.

Effects of Nb doping on thermoelectric properties of Zn4Sb3 at high temperatures

2009 ◽  
Vol 24 (2) ◽  
pp. 430-435 ◽  
Author(s):  
D. Li ◽  
H.H. Hng ◽  
J. Ma ◽  
X.Y. Qin
Keyword(s):  
Thermal Conductivity ◽  
Electrical Resistivity ◽  
High Temperatures ◽  
Thermoelectric Properties ◽  
Figure Of Merit ◽  
Thermoelectric Performance ◽  
Temperature Range ◽  
A Value ◽  
Nb Doping ◽  
Thermal Conductivities

The thermoelectric properties of Nb-doped Zn4Sb3 compounds, (Zn1–xNbx)4Sb3 (x = 0, 0.005, and 0.01), were investigated at temperatures ranging from 300 to 685 K. The results showed that by substituting Zn with Nb, the thermal conductivities of all the Nb-doped compounds were lower than that of the pristine β-Zn4Sb3. Among the compounds studied, the lightly substituted (Zn0.995Nb0.005)4Sb3 compound exhibited the best thermoelectric performance due to the improvement in both its electrical resistivity and thermal conductivity. Its figure of merit, ZT, was greater than the undoped Zn4Sb3 compound for the temperature range investigated. In particular, the ZT of (Zn0.995Nb0.005)4Sb3 reached a value of 1.1 at 680 K, which was 69% greater than that of the undoped Zn4Sb3 obtained in this study.

The Influence of Silicon Dopant and Processing on Thermoelectric Properties of B4C Ceramics

1998 ◽  
Vol 545 ◽  
Author(s):  
Ke-Feng Cai ◽  
Ce-Wen Nan ◽  
Xin-Min Min
Keyword(s):  
Electrical Conductivity ◽  
Seebeck Coefficient ◽  
Thermoelectric Properties ◽  
Hot Pressing ◽  
Figure Of Merit ◽  
Room Temperature ◽  
A Value ◽  
Si Doped

AbstractB4C ceramics doped with various content of Si (0 to 2.03 at%) are prepared via hot pressing. The composition and microstructure of the ceramics are characterized by means of XRD and EPMA. Their electrical conductivity and Seebeck coefficient of the samples are measured from room temperature up to 1500K. The electrical conductivity increases with temperature, and more rapidly after 1300K; the Seebeck coefficient of the ceramics also increases with temperature and rises to a value of about 320μVK−1. The value of the figure of merit of Si-doped B4C rises to about 4 × 10−4K−1 at 1500K.

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.

Thermoelectric Properties of K2Bi8−xSbxSe13Solid Solutions and Se Doping

2001 ◽  
Vol 691 ◽  
Author(s):  
Theodora Kyratsi ◽  
Jeffrey S. Dyck ◽  
Wei Chen ◽  
Duck-Young Chung ◽  
Ctirad Uher ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Charge Transport ◽  
Transport Properties ◽  
Thermoelectric Properties ◽  
Solid Solutions ◽  
Figure Of Merit ◽  
Lattice Thermal Conductivity ◽  
Se Doping ◽  
Mass Fluctuation ◽  
Thermal Conductivities

ABSTRACTOur efforts to improve the thermoelectric properties of β-K2Bi8Se13, led to systematic studies of solid solutions of the type β-K2Bi8−xSbxSe13. The charge transport properties and thermal conductivities were studied for selected members of the series. Lattice thermal conductivity decreases due to the mass fluctuation generated in the lattice by the mixed occupation of Sb and Bi atoms. Se excess as a dopant was found to increase the figure-of merit of the solid solutions.

Thermoelectric Properties of Bi-Sb-Te-X Compounds Prepared by MA-PDS Method

2001 ◽  
Vol 691 ◽  
Author(s):  
Yong-Ho Park ◽  
Liu Xue-Dong
Keyword(s):  
Thermoelectric Properties ◽  
Figure Of Merit ◽  
Room Temperature ◽  
Ag Addition

ABSTRACTA great potential for further improving the room-temperature figure of merit (Z) has been identified by dispersing a small fraction of Ag in the (Bi0.25Sb0.75)2Te3 alloy. The maximum Z of 3.41×10−3K−1, 17% higher than that of the unadded, is attained at 0.02wt% Ag. Addition of BN, either alone or in combination with Ag, however, does not generate a favorable figure of merit.

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