A Comparison of the Mössbauer Effect Spectra of R₂Fe₁₄B and R₂Fe₁₄C

Author

Gary J. Long, Missouri University of Science and TechnologyFollow
R. Kulasekere
Oran Allan Pringle, Missouri University of Science and TechnologyFollow
Fernande Grandjean, Missouri University of Science and TechnologyFollow
K. H. Buschow

Abstract

The Mössbauer spectra of R₂Fe₁₄B, where R is La, Tb, Dy, Ho and Lu, have been measured at 295 K and the Mössbauer spectra of R₂Fe₁₄C, where R is Nd, Ho and Gd, have been measured at various temperatures between 85 and 295 K. All of the resulting spectra have been successfully analyzed with the same model used earlier to fit the spectra of various related compounds. The results indicate that the weighted average hyperfine field increases uniformly from La to Gd and decreases uniformly from Gd to Lu in R₂Fe₁₄B, as was found earlier for R₂Fe₁₄C. The weighted average isomer shift decreases by 0.04 mm/s in going from La₂Fe₁₄B to Lu₂Fe₁₄B, because of a decrease in the unit cell volume and an increase of the number of electrons in the unit cell, a decrease which corresponds to a 13.5% increase in the electron density. The use of the same model for both the Nd, Gd, Tb, Dy, Ho and Lu borides and carbides permits a detailed comparison of the Mössbauer hyperfine parameters in the two series of compounds. There is a linear correlation of the hyperfine fields at each of the sites in these two series of compounds, indicating that the replacement of boron by carbon has a long-range effect on the magnetic exchange within these materials. There is a correlation of the isomer shifts of the 8j₁, 8j₂ and 16k₂ sites in the two series of compounds. In contrast the isomer shift of the 16k₁ site show the chemical influence of replacing boron by carbon. With the expected exception of the 4c site there is a correlation between the quadrupole interactions in the two series of compounds. The Nd₂Fe₁₄B and Nd₂Fe₁₄C compounds have relatively low effective Mössbauer temperatures as compared to the borides and carbides with the heavier rare-earth elements.

Recommended Citation

G. J. Long et al., "A Comparison of the Mössbauer Effect Spectra of R₂Fe₁₄B and R₂Fe₁₄C," Journal of Magnetism and Magnetic Materials, vol. 117, no. 2016-01-02, pp. 239 - 250, Elsevier, Nov 1992.

The definitive version is available at https://doi.org/10.1016/0304-8853(92)90317-H

Department(s)

Chemistry

Second Department

Physics

Keywords and Phrases

Boron; Electronic Properties; Magnetic Properties; Mössbauer Spectroscopy; Hyperfine Fields; Rare Earth Compounds

International Standard Serial Number (ISSN)

0304-8853

Document Type

Article - Journal

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 1992 Elsevier, All rights reserved.

Publication Date

01 Nov 1992