Synthesis of filled skutterudite compounds: BayFexCo4−xSb12

2000 ◽  
Vol 15 (11) ◽  
pp. 2276-2279 ◽  
Author(s):  
L. Chen ◽  
X. Tang ◽  
T. Goto ◽  
T. Hirai
Keyword(s):  
Lattice Constant ◽  
Ternary Compound ◽  
Single Phase ◽  
Binary Compound ◽  
Solid Reaction ◽  
Filling Fraction ◽  
Filled Skutterudite ◽  
Reaction Method ◽  
Fe Content

Ba-filled skutterudite compounds, BayFexCo4−xSb12, were synthesized by a two-step solid reaction method. A binary compound of Sb3Ba and a ternary compound of FexCo1−xSb2 were first synthesized at 900 and 973 K, respectively. The presynthesized Sb3Ba and FexCo1−xSb2 were then mixed with Sb and heated at 973 K in an Ar atmosphere. The resulting powder was of single phase with a composition of BayFexCo4−xSb12, having skutterudite structure with the Sb–dodecahedron voids fractionally filled by Ba. The lattice constant of BayFexCo4−xSb12 increased with Ba and Fe content. The maximum filling fraction of Ba (ymax) in BayFexCo4−xSb12 was found to be greater than that of Ce or La in LnyFexCo4−xSb12, especially in the lower Fe content region. The ymax varied from 0.35 to near 1.0 when Fe content (x) changed from 0 to 4.

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.

Theoretical Study of the Filling Fraction Limit of Fe-Substituted Ba-Filled Skutterudite BayFe4xCo4-4xSb12

2012 ◽  
Vol 519 ◽  
pp. 169-173
Author(s):  
Zhuo Chen ◽  
Jiong Yang
Keyword(s):  
Lattice Constant ◽  
Theoretical Study ◽  
First Principle ◽  
Secondary Phases ◽  
Filling Fraction ◽  
Filled Skutterudite ◽  
Fe Content

Theoretical study of the filling fraction limit (FFL) of the Fe-substituted Ba-filled skutterudite was carried out via first principle method calculations. The lattice constant of BayFe4xCo4-4xSb12 increases with the Ba filling fraction under fixed Fe content while it does not simply increases with Fe content under fixed Ba filling fraction. The FFL is determined by the competition between the formation of filled skutterudite phases and the corresponding secondary phases. The FFL of Ba in the Fe-substituted CoSb3 skutterudites increases monotonically from 37.5% with Fe content of 0 to 100% with Fe content of ~50%. The most stable composition of the BayFe4xCo4-4xSb12is expected to be BayFe2.8Co1.2Sb12.

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.

Synthesis and Lattice Thermal Conductivity of Double Atoms Filling p-Type CamCenFexCo4-xSb12 Compounds

2007 ◽  
Vol 336-338 ◽  
pp. 838-841
Author(s):  
Han Li ◽  
Xin Feng Tang ◽  
Tao Xiang Liu ◽  
Chen Song ◽  
Qing Jie Zhang
Keyword(s):  
Thermal Conductivity ◽  
Rietveld Refinement ◽  
Single Phase ◽  
Lattice Thermal Conductivity ◽  
Melting Reaction ◽  
Filling Fraction ◽  
Reaction Method ◽  
P Type

Single-phase double atoms filling skutterudite compounds were synthesized by using melting reaction method. The effects of double atoms filling on the structure and lattice thermal conductivity of skutterudite compounds were investigated. The results of Rietveld refinement indicate that CamCenFexCo4-xSb12 compounds possess skutterudite structure and the Sb-icosahedron voids have been partially filled with filling atoms. With the same filling fraction, the lattice thermal conductivity of CamCenFexCo4-xSb12 is smaller than that of CamFexCo4-xSb12 and CenFexCo4-xSb12, furthermore, when the total filling fraction (m+n) is about 0.3 and respective filling fraction of Ca and Ce are approximately equal, the lattice thermal conductivity is the least.

scholarly journals Single Step Process for Crystalline Ni-B Compounds

Materials ◽  
2018 ◽  
Vol 11 (7) ◽  
pp. 1259 ◽  
Author(s):  
Mahboobeh Shahbazi ◽  
Henrietta Cathey ◽  
Natalia Danilova ◽  
Ian Mackinnon
Keyword(s):  
Single Phase ◽  
Single Step ◽  
Transformation Mechanism ◽  
Solid Reaction ◽  
Step Method ◽  
Step Process ◽  
Pressure Time ◽  
Autogenous Pressure ◽  
Higher Temperature ◽  
High Yields

Crystalline Ni2B, Ni3B, and Ni4B3 are synthesized by a single-step method using autogenous pressure from the reaction of NaBH4 and Ni precursors. The effect of reaction temperature, pressure, time, and starting materials on the composition of synthesized products, particle morphologies, and magnetic properties is demonstrated. High yields of Ni2B (>98%) are achieved at 2.3–3.4 MPa and ~670 °C over five hours. Crystalline Ni3B or Ni4B3 form in conjunction with Ni2B at higher temperature or higher autogenous pressure in proportions influenced by the ratios of initial reactants. For the same starting ratios of reactants, a longer reaction time or higher pressure shifts equilibria to lower yields of Ni2B. Using this approach, yields of ~88% Ni4B3 (single phase orthorhombic) and ~72% Ni3B are obtained for conditions 1.9 MPa < Pmax < 4.9 MPa and 670 °C < Tmax < 725 °C. Gas-solid reaction is the dominant transformation mechanism that results in formation of Ni2B at lower temperatures than conventional solid-state methods.

scholarly journals Structure and electric properties of cerium substituted SrBi1.8Ce0.2Nb2O9 and SrBi1.8Ce0.2Ta2O9 ceramics

2016 ◽  
Vol 10 (3) ◽  
pp. 183-188 ◽  
Author(s):  
Mohamed Afqir ◽  
Amina Tachafine ◽  
Didier Fasquelle ◽  
Mohamed Elaatmani ◽  
Jean-Claude Carru ◽  
...  
Keyword(s):  
Dielectric Constant ◽  
Solid State ◽  
Room Temperature ◽  
Single Phase ◽  
Solid State Reaction Method ◽  
X Ray Diffraction ◽  
Reaction Method ◽  
X Ray ◽  
Lcr Meter ◽  
Curie Temperature Tc

SrBi1.8Ce0.2Nb2O9 (SBCN) and SrBi1.8Ce0.2Ta2O9 (SBCT) powders were prepared via solid-state reaction method. X-ray diffraction analysis reveals that the SBCN and SBCT powders have the single phase orthorhom-bic Aurivillius structure at room temperature. The contribution of Raman scattering and FTIR spectroscopy of these samples were relatively smooth and resemble each other. The calcined powders were uniaxially pressed and sintered at 1250?C for 8 h to obtaine dense ceramics. Dielectric constant, loss tangent and AC conductivity of the sintered Ce-doped SrBi2Nb2O9 and SrBi2Ta2O9 ceramics were measured by LCR meter. The Ce-doped SBN (SBCN) ceramics have a higher Curie temperature (TC) and dielectric constant at TC (380?C and ?? ~3510) compared to the Ce-doped SBT (SBCT) ceramics (330?C and ?? ~115) when measured at 100Hz. However, the Ce-doped SBT (SBCT) ceramics have lower conductivity and dielectric loss.

Preparation and Investigation on Properties of the MgTiO3-CaTiO3 Microwave Ceramic Materials

2014 ◽  
Vol 997 ◽  
pp. 419-423 ◽  
Author(s):  
Li Dong ◽  
Gui Xia Dong ◽  
Yuan Yuan Li ◽  
Xi Zhang
Keyword(s):  
Dielectric Constant ◽  
Sintering Temperature ◽  
Ceramic Materials ◽  
Volume Density ◽  
Second Phase ◽  
Pressureless Sintering ◽  
Solid Reaction ◽  
Reaction Method ◽  
Microwave Ceramic ◽  
Sintering Method

The MgTiO3 and CaTiO3 powders were synthesized by solid reaction method, and MgTiO3-CaTiO3 ceramic was prepared using pressureless sintering method. The experiment prepared MgTiO3-CaTiO3 ceramics with high compactness and stable permittivity by the way of changing the mole ratio of MgTiO3 and CaTiO3 to investigate the effect of CaTiO3 on the performances of MgTiO3-CaTiO3 ceramics. The results show that Mg2TiO4 formed as second phase during sintering. Volume density and dielectric constant of MgTiO3-CaTiO3 ceramics with 10%mol CaTiO3 reach maximum of 3.612g/cm3 and 17.8, respectively, under 1460°C sintering temperature. And for the MgTiO3-CaTiO3 ceramics with 5%mol CaTiO3 the maximum values which are 3.5g/cm3 and 16.6, respectively, appear under 1510°C sintering temperature.

Synthetic Processes via Complex Precursors of Rare Earth Manganites with the Perovskite and its Related Structures

2004 ◽  
Vol 449-452 ◽  
pp. 725-728 ◽  
Author(s):  
A. Shimono ◽  
Hirohisa Sato ◽  
K. Kawada-Wada ◽  
Yasuo Ito ◽  
Naoki Kamegashira
Keyword(s):  
Rare Earth ◽  
Single Phase ◽  
Solid State Reaction Method ◽  
Rare Earth Complex ◽  
Normal Process ◽  
Composition Region ◽  
Synthetic Process ◽  
Reaction Method ◽  
X Ray ◽  
Rare Earth Manganites

A development of synthetic process via rare earth complex precursors was applied to a formation of rare earth manganites which can not be easily formed by conventional (normal) process. Several compounds of rare earth manganites with various structures were successfully synthesized by this method and their crystal structures were identified by powder X-ray diffractometry. Both of the orthorhombic and rhombohedral LaMnO3phases were prepared. LnMn2O5phase was more easily prepared by this method than by another method. The solid solution of (Sr,La)2MnO4phase for various compositions were tried to prepare a single phase, especially for a composition region Sr/La ratio < 1. since this phase is normally formed for only region of Sr/La ratio .. 1 by the solid state reaction method.

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.

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