Thermoelectric properties of hole-doped Yb1-xPbxBaCo4O7+δ ceramics

2015 ◽  
Vol 29 (14) ◽  
pp. 1550082 ◽  
Author(s):  
Yubo Chen ◽  
Runxiang Ma ◽  
Kunlun Wang ◽  
Feng Gao ◽  
Xing Hu ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Electrical Resistivity ◽  
Solid State ◽  
Figure Of Merit ◽  
Solid State Reaction Method ◽  
Doping Content ◽  
Reaction Method ◽  
Dimensionless Figure Of Merit ◽  
Ceramic Samples ◽  
Pb Doping

The effects of Pb doping on the thermoelectric (TE) properties of Yb 1-x Pb x BaCo4O7+δ (x = 0, 0.02, 0.04, 0.06, 0.08 and 0.1) ceramic samples prepared by the solid-state reaction method were investigated from 383 K to 973 K. The results showed that with increase of the Pb content, the electrical resistivity decreased remarkably, meanwhile the Seebeck coefficient decreased slightly, resulting in an enhancement of the power factor (PF). The effect of Pb doping on the thermal conductivity was insignificant. According to the PF and the dimensionless figure of merit (ZT) value, the optimum Pb doping content was x = 0.08. The ZT value reached 0.12 at 973 K, being 69.5% higher than that of the sample without Pb doping.

Influence of R3+ ion sizes on the thermoelectric properties of RBaCo4O7+δ ceramics

2015 ◽  
Vol 29 (26) ◽  
pp. 1550154 ◽  
Author(s):  
F. Gao ◽  
Q. L. He ◽  
F. Wu ◽  
D. L. Yang ◽  
X. Hu ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Electrical Resistivity ◽  
Solid State ◽  
Thermoelectric Properties ◽  
Solid State Reaction ◽  
Solid State Reaction Method ◽  
Oxygen Adsorption ◽  
Reaction Method ◽  
Transition Phenomenon ◽  
Seebeck Coefficients

The influence of [Formula: see text] ion sizes on the electrical resistivity, Seebeck coefficients, thermal conductivity and [Formula: see text] values of [Formula: see text] prepared by the solid-state reaction method was investigated from 373 K to 973 K. The electrical resistivity decreases with decreasing [Formula: see text] ion sizes. Both the electrical resistivity and the Seebeck coefficients have a transition at about 630 K. Especially, the transition phenomenon disappears gradually with decreasing [Formula: see text] ion sizes, and is attributed to the oxygen adsorption of [Formula: see text]. The [Formula: see text] values increase with rising temperature or decreasing [Formula: see text] ion sizes. The [Formula: see text] with the smallest [Formula: see text] size has the maximum [Formula: see text] value that reaches 0.1 at 973 K.

Effect of Ca and/or Mn substitution on thermoelectric properties of SrTiO3

2021 ◽  
Author(s):  
D. Mohan Radheep
Keyword(s):  
Thermal Conductivity ◽  
Electrical Resistivity ◽  
Thermoelectric Properties ◽  
Figure Of Merit ◽  
Room Temperature ◽  
Mixed Valence ◽  
Solid State Reaction Method ◽  
Reaction Method ◽  
Cubic Lattice ◽  
Mn Substitution

Thermoelectric properties have been investigated for Sr0.5Ca0.5Ti1-xMnxO3 (x = 0.25, 0.5, 0.75) and Sr0.75Ca0.25Ti0.75Mn0.25O3 perovskite polycrystalline samples synthesized by solid-state reaction method. Following physical properties such as thermal conductivity, electrical resistivity, Seebeck coefficient, power factor and figure of merit (ZT) were measured. The substitution of Ca2+ in Sr2+ site or/and mixed valence Mn in Ti site creates appreciable enhancement in the thermoelectric properties with an increase of ZT from 0.5 to 0.69 at room temperature. The origin for the enrichment of ZT of the investigated samples around room temperature is due to substitution induced distortion in the cubic lattice.

Thermoelectric Properties of Tl-X-Te (X=Pb, Sn, Ge) Systems

2005 ◽  
Vol 886 ◽  
Author(s):  
Atsuko Kosuga ◽  
Ken Kurosaki ◽  
Hiroaki Muta ◽  
Shinsuke Yamanaka
Keyword(s):  
Thermal Conductivity ◽  
Electrical Resistivity ◽  
Solid State ◽  
Electrical Properties ◽  
Seebeck Coefficient ◽  
Thermoelectric Properties ◽  
Figure Of Merit ◽  
Room Temperature ◽  
Lattice Thermal Conductivity ◽  
Dimensionless Figure Of Merit

ABSTRACTPolycrystalline-sintered samples of Tl2GeTe3, Tl4SnTe3, and Tl4PbTe3 were prepared by a solid-state reaction. Their thermoelectric properties were evaluated at temperatures ranging from room temperature to ca. 700 K by using the measured electrical resistivity (ρ), Seebeck coefficient (S), and thermal conductivity (κ). Despite their poor electrical properties, the dimensionless figure of merit ZT of all the compounds was relatively high, i.e., 0.74 at 673 K for Tl4SnTe3, 0.71 at 673 K for Tl4PbTe3, 0.29 at 473 K for Tl2GeTe3, due to the very low lattice thermal conductivity of the compounds.

scholarly journals Thermoelectric Study of La2Ti2-xNbxO7 (0≤x≤0.25) Ceramic Materials

2020 ◽  
pp. 38-47
Author(s):  
A. C. Iyasara ◽  
F. U. Idu ◽  
E. O. Nwabineli ◽  
T. C. Azubuike ◽  
C. V. Arinze
Keyword(s):  
Crystal Structure ◽  
Thermal Conductivity ◽  
Solid State ◽  
Single Phase ◽  
Ceramic Materials ◽  
Solid State Reaction Method ◽  
Reaction Method ◽  
Reducing Atmosphere ◽  
High Seebeck Coefficient ◽  
Porous Microstructures

La2Ti2-xNbxO7 (x = 0.00, 0.05, 0.10, 0.15, 0.20, 0.25) powders were synthesised via solid state reaction method, followed by sintering at 1673 K in a reducing atmosphere of 5% H2/N2 gas. The crystal structure, microstructure and thermoelectric (TE) properties of the pure and Nb-doped La2Ti2O7 ceramics were investigated. All compositions were single phase with porous microstructures consistent with their low experimental densities. Thermoelectric results of Nb-doped compositions showed improved properties in comparison to pure La2Ti2O7, suggesting that cation doping has the potential to improve the thermoelectric properties. Generally, the TE results obtained are not suitable for thermoelectric applications. However, the high Seebeck coefficient (≥190 μV/K) and glass-like thermal conductivity ( ≤2.26 w / m.k )  values achieved have opened a new window for exploring the thermoelectric potentials of La2Ti2O7 and other related oxides.

Effect of Ni in new skutterudite compounds CaxCo4Sb12

2003 ◽  
Vol 793 ◽  
Author(s):  
Matthieu Puyet ◽  
Bertrand Lenoir ◽  
Anne Dauscher ◽  
Hubert Scherrer ◽  
Moukrane Dehmas ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Electrical Resistivity ◽  
Thermal Properties ◽  
Beneficial Effect ◽  
Transport Properties ◽  
Figure Of Merit ◽  
Positive Influence ◽  
Temperature Range ◽  
Dimensionless Figure Of Merit ◽  
Ni Substitution

ABSTRACTThe transport properties of the partially filled CaxCo4-yNiySb12 skutterudite compounds have been investigated in the 300 – 800 K temperature range. We underline the positive influence of the Ni substitution on the electrical resistivity and thermopower while the thermal properties – thermal conductivity – remains almost unaffected. These results suggest again a beneficial effect of Ni atoms on the dimensionless figure of merit in CoSb3 based compounds.

Influence of Sintering Temperatures on Microstructures and the Thermal Conductivity of CuAlO2 Ceramics

2016 ◽  
Vol 848 ◽  
pp. 222-227 ◽  
Author(s):  
Zi Jun Song ◽  
Lian Jun Wang ◽  
Wan Jiang ◽  
Wei Luo
Keyword(s):  
Thermal Conductivity ◽  
Thermal Stability ◽  
Solid State ◽  
Room Temperature ◽  
Solid State Reaction Method ◽  
Oxide Ceramic ◽  
Synthetic Process ◽  
Reaction Method ◽  
Environmental Friendly ◽  
Different Temperatures

Oxide ceramic is a kind of environmental friendly materials, which has attracted more and more interests for its bunch of advantages such as sound chemical, thermal stability, simple synthetic process, cheap price, harmless and safety. Therefore, Oxide ceramic will be a promising material in the future. In this work, polycrystalline samples of CuAlO2 were prepared by a solid state reaction method. The mixture of pure CuO and Al2O3 powders was firstly pressed under the pressure of 60 MPa, and then 200 MPa to prepare pellets of 5 mm thick and 10 mm in diameter. The green compacts were sintered at five different temperatures (1273 K, 1323 K, 1373 K, 1423 K, 1473 K) for various holding times (5 h, 10 h and 15 h) in the air and then the furnace cooled. The crystalline and microstructures of the sintered CuAlO2 bodies were detected by XRD and SEM. The properties of density, thermal conductivity were also investigated in detail. The experimental results show that CuAlO2 bodies were rhombohedral, belonging to R3m space group. It is found that the density and the thermal conductivity of CuAlO2 ceramics were significantly dependent on the sintering temperatures. The density and thermal conductivity increased with increasing the sintering temperatures. The thermal conductivity of samples sintered at 1273 and 1473 K with the same holding time (10 h) were 9.70 and 35.53 W/mk at the room temperature, 3.41 and 8.29 W/mk at 1100 K, respectively.

Decreased Thermal Conductivity of CaMnO3 by Added-CNTs

2013 ◽  
Vol 770 ◽  
pp. 327-330
Author(s):  
Prapawan Thongsri ◽  
Tosawat Seetawan
Keyword(s):  
Thermal Conductivity ◽  
Manganese Oxide ◽  
Figure Of Merit ◽  
Solid State Reaction Method ◽  
Precursor Powder ◽  
Molar Ratio ◽  
Sintering Process ◽  
X Ray Diffraction ◽  
X Ray ◽  
Dimensionless Figure Of Merit

The CaMnO3compound is synthesized by solid state reaction method. The precursor powder of calcium carbonate (CaCO3) and manganese oxide (MnO2) are mixed by ball milling then calcined at 850°C for 10 h and sintering at 1,150 °C for 36 h to obtain the calcium manganese oxide (CaMnO3) compound. The compound was doped the carbon nanotubes (CNTs) 2%, 4%, 6%, 8% and 10% by molar ratio following the calcinations and sintering process. The morphology and crystallography of the samples are analyzed by the X-ray diffraction (XRD) technique and scanning electron microscope (SEM). The Seebeck coefficient (S), electrical resistivity (ρ), thermal conductivity (κ) and dimensionless figure of merit were anlyzed. It results shown in a good thermoelectric properties after doping CNTs.

scholarly journals Thermoelectric Study of La2Ti2-xNbxO7 (0 ≤ x ≤ 0.25) Ceramics

2020 ◽  
Author(s):  
Adindu Cyril Iyasara ◽  
Felix U Idu
Keyword(s):  
Crystal Structure ◽  
Thermal Conductivity ◽  
Solid State ◽  
Seebeck Coefficient ◽  
Single Phase ◽  
Solid State Reaction Method ◽  
Reaction Method ◽  
Reducing Atmosphere ◽  
High Seebeck Coefficient ◽  
Porous Microstructures

Abstract La2Ti2 − xNbxO7 (x = 0.00, 0.05, 0.10, 0.15, 0.20, 0.25) powders were synthesised via solid state reaction method, followed by sintering at 1673 K in a reducing atmosphere of 5% H2/N2 gas. The crystal structure, microstructure and thermoelectric (TE) properties of the pure and Nb-doped La2Ti2O7 ceramics were investigated. All compositions were single phase with porous microstructures consistent with their low experimental densities. Thermoelectric results of Nb-doped compositions showed improved properties in comparison to pure La2Ti2O7, suggesting that cation doping has the potential to improve the thermoelectric properties. Generally, the TE results obtained are not suitable for thermoelectric applications. However, the high Seebeck coefficient ( \ge 190 µV/K) and glass-like thermal conductivity ( \le 2.26 \text{W}/\text{m}.\text{K}) values achieved have opened a new window for exploring the thermoelectric potentials of La2Ti2O7 and other related oxides.

Structural, Magnetic and Superconducting Properties of the Y1-xZrxBa2-2xCa2xCu3O7-δ Compounds

1997 ◽  
Vol 11 (26n27) ◽  
pp. 1175-1180
Author(s):  
Iosif Gr. Deac ◽  
Iuliu Pop ◽  
Viorel Pop ◽  
Ioan Burda
Keyword(s):  
Electrical Resistivity ◽  
Magnetic Susceptibility ◽  
Solid State ◽  
Stoichiometric Composition ◽  
Solid State Reaction Method ◽  
Spin Fluctuations ◽  
Superconducting Properties ◽  
Reaction Method ◽  
X Ray ◽  
Ca Ions

Samples with stoichiometric composition Y 1-x Zr x Ba 2-2x Ca 2x Cu3O7-δ with x=0.0, 0.1, 0.2, 0.3 were prepared by the solid state reaction method. The effect of Zr and Ca, doped at the Y and respectively Ba sites simultaneously in the Y:123 composition was studied. The phase and lattice parameters of the compounds were determined by X-ray powder diffraction measurements. We also discuss the distribution of the Ca ions between the Y and Ba sites when Y is partially replaced by Zr. Superconductivity was analyzed by both electrical resistivity and magnetic susceptibility measurements. The results suggest the assumption that the substitutions could increase the number of isolated Cu 2+ spin 1/2 defects and/or to change the energy of the spin fluctuations.

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