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Title: Phase stability and lattice thermal conductivity reduction in CoSb{sub 3} skutterudites, doped with chalcogen atoms

Abstract

We report a significant reduction in the lattice thermal conductivity of the CoSb{sub 3} skuttertudites, doped with chalcogen atoms. Te/Se chalcogen atoms doped CoSb{sub 3} skutterudite samples (Te{sub 0.1}Co{sub 4}Sb{sub 12}, Se{sub 0.1}Co{sub 4}Sb{sub 12}, Te{sub 0.05}Se{sub 0.05}Co{sub 4}Sb{sub 12}) are processed by ball milling and spark plasma sintering. X-ray diffraction data combined with energy dispersive X-ray spectra indicate the doping of Te/Se chalcogen atoms in the skutterudite. The temperature dependent X-ray diffraction confirms the stability of the Te/Se doped CoSb{sub 3} skutterudite phase and absence of any secondary phase in the temperature range starting from 300 K to 773 K. The Raman spectroscopy reveals that different chalcogen dopant atoms cause different resonant optical vibrational modes between the dopant atom and the host CoSb{sub 3} skutterudite lattice. These optical vibrational modes do scatter heat carrying acoustic phonons in a different spectral range. It was found that among the Te/Se chalcogen atoms, Te atoms alter the host CoSb{sub 3} skutterudite lattice vibrations to a larger extent than Se atoms, and can potentially scatter more Sb related acoustic phonons. The Debye model of lattice thermal conductivity confirms that the resonant phonon scattering has important contributions to the reduction of lattice thermal conductivitymore » in CoSb{sub 3} skutterudites doped with Te/Se chalcogen atoms. Lattice thermal conductivity ∼ 0.9 W/mK at 773 K is achieved in Te{sub 0.1}Co{sub 4}Sb{sub 12} skutterudites, which is the lowest value reported so far in CoSb{sub 3} skutterudites, doped with single Te chalcogen atom.« less

Authors:
; ;  [1]; ;  [2]
  1. International Advanced Research Centre for Powder Metallurgy and New Materials (ARCI), IIT M Research Park, Taramani, Chennai-600113 (India)
  2. Department of Physics, Indian Institute of Technology Madras, Chennai-600036 (India)
Publication Date:
OSTI Identifier:
22611464
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Advances; Journal Volume: 6; Journal Issue: 7; Other Information: (c) 2016 Author(s); Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; ANTIMONY; ATOMS; CHALCOGENIDES; COBALT COMPOUNDS; DOPED MATERIALS; LATTICE VIBRATIONS; MILLING; PHASE STABILITY; PHONONS; PLASMA; RAMAN SPECTROSCOPY; REDUCTION; SELENIUM ADDITIONS; SINTERING; TELLURIUM ADDITIONS; TEMPERATURE DEPENDENCE; THERMAL CONDUCTIVITY; X-RAY DIFFRACTION; X-RAY SPECTRA

Citation Formats

Battabyal, M., E-mail: manjusha.battabyal@project.arci.res.in, Priyadarshini, B., Gopalan, R., Pradipkanti, L., and Satapathy, Dillip K. Phase stability and lattice thermal conductivity reduction in CoSb{sub 3} skutterudites, doped with chalcogen atoms. United States: N. p., 2016. Web. doi:10.1063/1.4959102.
Battabyal, M., E-mail: manjusha.battabyal@project.arci.res.in, Priyadarshini, B., Gopalan, R., Pradipkanti, L., & Satapathy, Dillip K. Phase stability and lattice thermal conductivity reduction in CoSb{sub 3} skutterudites, doped with chalcogen atoms. United States. doi:10.1063/1.4959102.
Battabyal, M., E-mail: manjusha.battabyal@project.arci.res.in, Priyadarshini, B., Gopalan, R., Pradipkanti, L., and Satapathy, Dillip K. 2016. "Phase stability and lattice thermal conductivity reduction in CoSb{sub 3} skutterudites, doped with chalcogen atoms". United States. doi:10.1063/1.4959102.
@article{osti_22611464,
title = {Phase stability and lattice thermal conductivity reduction in CoSb{sub 3} skutterudites, doped with chalcogen atoms},
author = {Battabyal, M., E-mail: manjusha.battabyal@project.arci.res.in and Priyadarshini, B. and Gopalan, R. and Pradipkanti, L. and Satapathy, Dillip K.},
abstractNote = {We report a significant reduction in the lattice thermal conductivity of the CoSb{sub 3} skuttertudites, doped with chalcogen atoms. Te/Se chalcogen atoms doped CoSb{sub 3} skutterudite samples (Te{sub 0.1}Co{sub 4}Sb{sub 12}, Se{sub 0.1}Co{sub 4}Sb{sub 12}, Te{sub 0.05}Se{sub 0.05}Co{sub 4}Sb{sub 12}) are processed by ball milling and spark plasma sintering. X-ray diffraction data combined with energy dispersive X-ray spectra indicate the doping of Te/Se chalcogen atoms in the skutterudite. The temperature dependent X-ray diffraction confirms the stability of the Te/Se doped CoSb{sub 3} skutterudite phase and absence of any secondary phase in the temperature range starting from 300 K to 773 K. The Raman spectroscopy reveals that different chalcogen dopant atoms cause different resonant optical vibrational modes between the dopant atom and the host CoSb{sub 3} skutterudite lattice. These optical vibrational modes do scatter heat carrying acoustic phonons in a different spectral range. It was found that among the Te/Se chalcogen atoms, Te atoms alter the host CoSb{sub 3} skutterudite lattice vibrations to a larger extent than Se atoms, and can potentially scatter more Sb related acoustic phonons. The Debye model of lattice thermal conductivity confirms that the resonant phonon scattering has important contributions to the reduction of lattice thermal conductivity in CoSb{sub 3} skutterudites doped with Te/Se chalcogen atoms. Lattice thermal conductivity ∼ 0.9 W/mK at 773 K is achieved in Te{sub 0.1}Co{sub 4}Sb{sub 12} skutterudites, which is the lowest value reported so far in CoSb{sub 3} skutterudites, doped with single Te chalcogen atom.},
doi = {10.1063/1.4959102},
journal = {AIP Advances},
number = 7,
volume = 6,
place = {United States},
year = 2016,
month = 7
}
  • Ab-initio calculations of the resonant modes and frequencies for a number of possible fillers in p-type RFe₃CoSb₁₂ and RFe₄Sb₁₂ were carried out. The results indicate that, although the exact values of fillers’ resonant frequencies in p-type skutterudites are somewhat different from those in n-type Co-based skutterudites, the Einstein-like resonant modes of the fillers are similar to those in n-type materials. Experimentally, several pairs of the fillers were selected and double-filled p-type skutterudite compounds R{sub x}M{sub y}Fe₃CoSb₁₂ (R, M = Ba, Ce, Nd, and Yb) were successfully synthesized. The reduction in the lattice thermal conductivity was realized by extending the rangemore » of resonant frequencies. As a result, enhanced ZT values above unity were achieved in these double-filled p-type skutterudites.« less
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  • Recently, we found a new n-type thermoelectric half-Heusler NbCoSb with a valence electron count of 19, different from the usual 18. In this paper, we focus on the effect of partial substitution of Nb by isoelectronic elements V and Ta on the reduction of the thermal conductivity of Nb(1-x)/2V(1-x)/2TaxCoSb. We found that the isoelectronic elements V and Ta for partial substitution of Nb can dramatically decrease the thermal conductivity from 7.0 W m-1 K-1 to 3.3 W m-1 K-1 at room temperature for Nb0.44V0.44Ta0.12CoSb, but unfortunately a large power factor decrease also occurred. Consequently, a peak ZT of ~0.5 ismore » achieved at 700 °C for Nb0.44V0.44Ta0.12CoSb, which is about 25% higher than the ~0.4 reported earlier for NbCoSb.« less
  • Here, in this study, novel filled skutterudites Ba yNi 4Sb 12-xSn x (y max = 0.93) have been prepared by arc melting followed by annealing at 250, 350 and 450°C up to 30 days in vacuum-sealed quartz vials. Extension of the homogeneity region, solidus temperatures and structural investigations were performed for the skutterudite phase in the ternary Ni–Sn–Sb and in the quaternary Ba–Ni–Sb–Sn systems. Phase equilibria in the Ni–Sn–Sb system at 450°C were established by means of Electron Probe Microanalysis (EPMA) and X-ray Powder Diffraction (XPD). With rather small cages Ni 4(Sb,Sn) 12, the Ba–Ni–Sn–Sb skutterudite system is perfectly suitedmore » to study the influence of filler atoms on the phonon thermal conductivity. Single-phase samples with the composition Ni 4Sb 8.2Sn 3.8, Ba 0.42Ni 4Sb 8.2Sn 3.8 and Ba 0.92Ni 4Sb 6.7Sn 5.3 were used to measure their physical properties, i.e. temperature dependent electrical resistivity, Seebeck coefficient and thermal conductivity. The resistivity data demonstrate a crossover from metallic to semiconducting behaviour. The corresponding gap width was extracted from the maxima in the Seebeck coefficient data as a function of temperature. Single crystal X-ray structure analyses at 100, 200 and 300 K revealed the thermal expansion coefficients as well as Einstein and Debye temperatures for Ba 0.73Ni 4Sb 8.1Sn 3.9 and Ba 0.95Ni 4Sb 6.1Sn 5.9. These data were in accordance with the Debye temperatures obtained from the specific heat (4.4 K < T < 140 K) and Mössbauer spectroscopy (10 K < T < 290 K). Rather small atom displacement parameters for the Ba filler atoms indicate a severe reduction in the “rattling behaviour” consistent with the high levels of lattice thermal conductivity. The elastic moduli, collected from Resonant Ultrasonic Spectroscopy ranged from 100 GPa for Ni 4Sb 8.2Sn 3.8 to 116 GPa for Ba 0.92Ni 4Sb 6.7Sn 5.3. The thermal expansion coefficients were 11.8 × 10 -6 K -1 for Ni 4Sb 8.2Sn 3.8 and 13.8 × 10 -6 K -1 for Ba 0.92Ni 4Sb 6.7Sn 5.3. The room temperature Vickers hardness values vary within the range from 2.6 GPa to 4.7 GPa. Lastly, severe plastic deformation via high-pressure torsion was used to introduce nanostructuring; however, the physical properties before and after HPT showed no significant effect on the materials thermoelectric behaviour.« less