Mössbauer Effect Study of Filled Antimonide Skutterudites

Author

Gary J. Long, Missouri University of Science and TechnologyFollow
Dimitri Hautot
Fernande Grandjean, Missouri University of Science and TechnologyFollow
Donald T. Morelli
Gregory P. Meisner

Abstract

The iron-57 Mössbauer spectra of a series of Ce-filled antimonide skutterudites, Ce_xFe_4-yCo_ySb₁₂, where x varies from 0.22 to 0.98 and y varies from 0 to 3.5, have been measured at 295 K. In addition, the spectra of Ce_0.60Fe₂Co₂Sb₁₂ and Ce_0.82Fe₃CoSb₁₂ have been measured from 85 to 295 K and the spectra of Ce_0.35FeCo₃Sb₁₂ and Ce_0.98Fe₄Sb₁₂ have been measured from 4.2 to 295 K. The spectra, all of which consist of a simple quadrupole doublet, show no evidence for any long-range magnetic ordering of any Fe magnetic moments. The 295-K quadrupole splitting increases linearly from 0.104 mm/s at x=0.22 to 0.415 mm/s at x =0.98, an increase which results from the increasing hole concentration in the valence band of these compounds. The quadrupole splitting of approximately 0.16 mm/s observed for Ce_0.35FeCo₃Sb₁₂ is virtually independent of temperature between 4.2 and 295 K and results predominantly from a lattice contribution to the electric-field gradient. In contrast, in Ce_0.98Fe₄Sb₁₂, the quadrupole splitting is constant at approximately 0.49 mm/s below approximately 70 K, and decreases with T^3/2 above 70 K. The 295-K isomer shift increases linearly from 0.345 mm/s at x=0.22 to 0.386 mm/s at x=0.98, an increase which results from a linear expansion of the unit-cell volume with increasing x. The temperature dependencies of the isomer shift and of the logarithm of the spectral absorption area in Ce_0.98Fe₄Sb₁₂ and Ce_0.35FeCo₃Sb₁₂ yield effective Mössbauer temperatures of approximately 500 and 400 K, respectively, values which are substantially higher than the Debye temperatures of approximately 300 K observed for these compounds. These differences indicate that the high-frequency vibrations of the iron sublattice are weakly coupled to the lower frequency vibrations of both the partially filled cerium sublattice and the antimony sublattice.

Recommended Citation

G. J. Long et al., "Mössbauer Effect Study of Filled Antimonide Skutterudites," Physical Review B (Condensed Matter), vol. 60, no. 10, pp. 7410 - 7418, American Physical Society (APS), Sep 1999.

The definitive version is available at https://doi.org/10.1103/PhysRevB.60.7410

Department(s)

Chemistry

Sponsor(s)

National Science Foundation (U.S.)

Keywords and Phrases

Antimonide; Mössbauer spectroscopy; Skutterudite

International Standard Serial Number (ISSN)

0163-1829

Document Type

Article - Journal

Document Version

Final Version

File Type

text

Language(s)

English

Rights

© 1999 American Physical Society (APS), All rights reserved.

Publication Date

01 Sep 1999