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Title: FP-LAPW calculations of the elastic, electronic and thermoelectric properties of the filled skutterudite CeRu{sub 4}Sb{sub 12}

Abstract

We have investigated the electronic structure, elastic and thermoelectric properties of the filled skutterudite CeRu{sub 4}Sb{sub 12} using the density functional theory (DFT). The full potential linearized augmented plane wave (FP-LAPW) method within a framework of the generalized gradient approximation (GGA) approach is used to perform the calculations presented here. The electronic structure calculation suggests an indirect band gap semiconducting nature of the material with energy band gap of 0.08 eV. The analysis of the elastic constants at relaxed positions reveals the ductile nature of the sample material with covalent contribution in the inter-atomic bonding. The narrow band gap semiconducting nature with high value of Seebeck coefficient suggests the possibility of the thermoelectric application of the material. The analysis of the thermal transport properties confirms the result obtained from the energy band structure of the material with high thermopower and dimensionless figure of merit 0.19 at room temperature.

Authors:
 [1];  [2];  [1];  [3];  [1]
  1. Condensed Matter Theory Group, Department of Physics, Mizoram University, 796004 (India)
  2. Department of Physics, Pachhunga University College, Aizawl 796001 (India)
  3. Laboratoire de Physique Quantique et de Modélisation Mathématique (LPQ3M), Département de Technologie, Université de Mascara, 29000 (Algeria)
Publication Date:
OSTI Identifier:
22584188
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Solid State Chemistry; Journal Volume: 240; Other Information: Copyright (c) 2016 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; 97 MATHEMATICAL METHODS AND COMPUTING; BONDING; DENSITY FUNCTIONAL METHOD; ELECTRONIC STRUCTURE; PERFORMANCE; TEMPERATURE RANGE 0273-0400 K; THERMOELECTRIC PROPERTIES

Citation Formats

Shankar, A., E-mail: amitshan2009@gmail.com, Rai, D.P., Chettri, Sandeep, Khenata, R., and Thapa, R.K. FP-LAPW calculations of the elastic, electronic and thermoelectric properties of the filled skutterudite CeRu{sub 4}Sb{sub 12}. United States: N. p., 2016. Web. doi:10.1016/J.JSSC.2016.05.027.
Shankar, A., E-mail: amitshan2009@gmail.com, Rai, D.P., Chettri, Sandeep, Khenata, R., & Thapa, R.K. FP-LAPW calculations of the elastic, electronic and thermoelectric properties of the filled skutterudite CeRu{sub 4}Sb{sub 12}. United States. doi:10.1016/J.JSSC.2016.05.027.
Shankar, A., E-mail: amitshan2009@gmail.com, Rai, D.P., Chettri, Sandeep, Khenata, R., and Thapa, R.K. Mon . "FP-LAPW calculations of the elastic, electronic and thermoelectric properties of the filled skutterudite CeRu{sub 4}Sb{sub 12}". United States. doi:10.1016/J.JSSC.2016.05.027.
@article{osti_22584188,
title = {FP-LAPW calculations of the elastic, electronic and thermoelectric properties of the filled skutterudite CeRu{sub 4}Sb{sub 12}},
author = {Shankar, A., E-mail: amitshan2009@gmail.com and Rai, D.P. and Chettri, Sandeep and Khenata, R. and Thapa, R.K.},
abstractNote = {We have investigated the electronic structure, elastic and thermoelectric properties of the filled skutterudite CeRu{sub 4}Sb{sub 12} using the density functional theory (DFT). The full potential linearized augmented plane wave (FP-LAPW) method within a framework of the generalized gradient approximation (GGA) approach is used to perform the calculations presented here. The electronic structure calculation suggests an indirect band gap semiconducting nature of the material with energy band gap of 0.08 eV. The analysis of the elastic constants at relaxed positions reveals the ductile nature of the sample material with covalent contribution in the inter-atomic bonding. The narrow band gap semiconducting nature with high value of Seebeck coefficient suggests the possibility of the thermoelectric application of the material. The analysis of the thermal transport properties confirms the result obtained from the energy band structure of the material with high thermopower and dimensionless figure of merit 0.19 at room temperature.},
doi = {10.1016/J.JSSC.2016.05.027},
journal = {Journal of Solid State Chemistry},
number = ,
volume = 240,
place = {United States},
year = {Mon Aug 15 00:00:00 EDT 2016},
month = {Mon Aug 15 00:00:00 EDT 2016}
}
  • Single-phase Ca{sub m}Ce{sub n}Fe{sub x}Co{sub 4-x}Sb{sub 12} compounds filled by Ca and Ce were synthesized by using melting-quench-diffusion annealing reaction method. The structure and thermoelectric properties of double atoms filled skutterudite compounds were investigated. The results of Rietveld refinement indicate high reliabilities of filling fractions consistent with the inductively coupled plasma atomic emission spectrometry (ICP-AES) analysis, Ca{sub m}Ce{sub n}Fe{sub x}Co{sub 4-x}Sb{sub 12} compounds possess skutterudite structure, and Sb-icosahedron voids were filled with Ca or Ce. The thermal parameter B{sub Ca/Ce} (6.0) of Ca/Ce is much larger than that of B{sub Sb} (0.3) and B{sub Fe/Co} (0.3) of Sb and Fe/Co.more » The specific chemical states of atoms were obtained from x-ray photoelectron spectroscopy quantitative analysis, which shows that Sb has five chemical states and the relative content is correlative with the total filling fraction; the filling atoms have three filling positions and tend to fill the center position of the Sb-icosahedron voids, preferentially. With the same filling fraction, carrier concentration and electrical conductivity of p-type Ca{sub m}Ce{sub n}Fe{sub x}Co{sub 4-x}Sb{sub 12} are intervenient between that of single atom filled compounds Ca{sub m}Fe{sub x}Co{sub 4-x}Sb{sub 12} and Ce{sub n}Fe{sub x}Co{sub 4-x}Sb{sub 12}, and decreased with increasing Ca and Ce, especially Ce, filling fraction. The Seebeck coefficients are increased with increasing total filling fraction, and the influence of Ce filling fraction to the Seebeck coefficients is more notable than that of Ca, and with the same filling fraction, the lattice thermal conductivity of Ca{sub m}Ce{sub n}Fe{sub x}Co{sub 4-x}Sb{sub 12} is smaller than that of Ca{sub m}Fe{sub x}Co{sub 4-x}Sb{sub 12} and Ce{sub n}Fe{sub x}Co{sub 4-x}Sb{sub 12}; furthermore, when the total filling fraction (m+n) is about 0.3 and the respective filling fraction of Ca and Ce is approximately identical, the lattice thermal conductivity reached the minimum value. The greatest ZT value of 1.2 was obtained at 750 K for p-type Ca{sub 0.18}Ce{sub 0.12}Fe{sub 1.45}Co{sub 2.55}Sb{sub 12} compound.« less
  • Single-phase R{sub y}M{sub x}Co{sub 4-x}Sb{sub 12}(x=0-3.0,y=0-0.7) compounds filled by Ce, Ba, and Y, and substituted by Fe and Ni are synthesized by using the solid-state reaction method and melting reaction method. The structure and the thermoelectric properties of R{sub y}M{sub x}Co{sub 4-x}Sb{sub 12} are investigated systematically. The thermal parameter (B) of Ba and Ce filled in Sb-icosahedron voids in the skutterudite structure is larger than that of Sb and Co (Fe). The maximum filling fraction of Ce and Ba (y{sub max}) for R{sub y}Fe{sub x}Co{sub 4-x}Sb{sub 12} increases with the increasing Fe content, and it is found that the maximummore » filling fraction of Ba (y{sub max}) is greater than that of Ce{sub y}Fe{sub x}Co{sub 4-x}Sb{sub 12}. The filling atoms Ba, Ce, and Y in Sb-icosahedron voids can reduce the lattice thermal conductivity of R{sub y}M{sub x}Co{sub 4-x}Sb{sub 12} compounds remarkably, and the lattice thermal conductivity decreases in the order of ionic radii decreasing of Ba{sup 2+}, Ce{sup 3+}, and Y{sup 3+}. When Ce and Ba filing fraction is 0.3-0.4, the lattice thermal conductivity of R{sub y}Fe{sub x}Co{sub 4-x}Sb{sub 12} compounds reaches a minimum value. The lattice thermal conductivity can be greatly reduced by substituting Co with Fe or Ni, and compared with Fe substitution, the substituted atoms Ni are more effective in reducing the lattice thermal conductivity. The filling atoms Ba, Ce, and Y, and the substituted atoms Fe and Ni influence electrical transport properties of R{sub y}M{sub x}Co{sub 4-x}Sb{sub 12} compounds significantly. The carrier concentration and electrical conductivity of p-type R{sub y}Fe{sub x}Co{sub 4-x}Sb{sub 12} increase with the increasing Fe content but decrease with the increasing R filling fraction. At the same carrier concentration, electrical conductivity of p-type Ba{sub y}Fe{sub x}Co{sub 4-x}Sb{sub 12} is larger than that of p-type Ce{sub y}Fe{sub x}Co{sub 4-x}Sb{sub 12}. Electrical conductivity of n-type Ba{sub y}Ni{sub x}Co{sub 4-x}Sb{sub 12} increases with the increasing Ni content remarkably. The Seebeck coefficient of p-type R{sub y}Fe{sub x}Co{sub 4-x}Sb{sub 12} increases with the increasing Ce and Ba filling fraction and with the decreasing Fe content, and Seebeck coefficient of n-type Ba{sub y}Ni{sub x}Co{sub 4-x}Sb{sub 12} decreases with the increasing Ni content. In the present study, the obtained maximum ZT values reach 1.1 and 1.25 for p-type Co-rich Ce{sub 0.28}Fe{sub 1.5}Co{sub 2.5}Sb{sub 12} (at 750 K) and n-type Ba{sub 0.30}Ni{sub 0.05}Co{sub 3.95}Sb{sub 12} (at 900 K), respectively.« less
  • Transport measurements, including magnetoresistivity, Hall resistivity, thermal conductivity, and thermopower, and an assessment of the dimensionless thermoelectric figure of merit ZT below room temperature are reported on a polycrystalline sample of the strongly correlated electron material YbFe{sub 4}Sb{sub 12}. Neutron diffraction measurements are presented, which reveal large amplitude thermal vibrations of the Yb ion, consistent with speculations that the ion is weakly bound in an oversized atomic ''cage'' formed in the skutterudite crystal structure. Infrared spectroscopy measurements reveal a resonance in the dissipative part of the optical conductivity {sigma}{sub 1}({omega}), which develops below T{sup *}{approx_equal}70 K, the characteristic temperature formore » the Yb ion valence fluctuations. The frequency dependence of the optical constants is suggestive of a hybridization band gap in the quasiparticle density of states at low temperatures. (c) 2000 The American Physical Society.« less
  • The thermoelectric properties on polycrystalline single (In) and double filled (Ce, In) skutterudites are characterized between 300 and 700 K. Powder neutron diffraction measurements of the skutterudite compositions In xCo 4Sb 12 (x= 0.05, 0.2) and Ce 0.05In 0.1Co 4Sb 12 as a function of temperature (12- 300 K) were carried out, which gives more insight into the structural data of single and double-filled skutterudites. Our results show that due to the annealing treatment, a Sb deficiency is detectable and thus verifies defects at the Sb lattice site of the skutterudite. Furthermore, we show by electron microprobe analysis that amore » considerable amount of indium is lost during synthesis and post-processing for the single indium filled samples, but not for the double cerium and indium skutterudite sample. The double-filled skutterudite is superior to the single-filled skutterudite composition due to a higher charge carrier density, a comparable lattice thermal resistivity, and a higher density of states effective mass in our experiment. Finally, we obtained a significantly higher Einstein temperature for the double-filled skutterudite composition in comparison to the single-filled species, which reflects the high sensitivity due to filling of the void lattice position within the skutterudite crystal.« less