Mössbauer Spectral Evidence for Rhombohedral Symmetry in R₃Fe₅O₁₂ Garnets with R = Y, Eu and Dy

Author

Denis Vandormael
Fernande Grandjean, Missouri University of Science and TechnologyFollow
Dimitri Hautot
Gary J. Long, Missouri University of Science and TechnologyFollow

Abstract

The iron-57 Mossbauer spectra of R₃Fe₅O₁₂, where R is Y, Eu and Dy, have been measured between 4.2 and 550 K. The substantial quadrupole splittings observed in the paramagnetic spectra confirm that the local symmetry at both the tetrahedral and octahedral iron(III) sites is not cubic. The low temperature Mossbauer spectra of Dy₃Fe₅O₁₂ clearly confirm the spin reorientation between 10 and 15 K and the 4.2 and 10 K spectra are consistent with the known orientation of the magnetization at 14 K in the cubic Ia3^-d unit cell. The Mossbauer spectra of R₃Fe₅O₁₂, where R is Y, Eu and Dy, obtained between 45 and 295 K, reveal four different tetrahedral iron(III) Mossbauer spectral components, four components which are inconsistent with a magnetization oriented along the [111] axis of a cubic Ia3^-d unit cell. In contrast, these four components are consistent with a crystal symmetry which is reduced from cubic to rhombohedral R3^-. The temperature dependence of the hyperfine fields in Dy₃Fe₅O₁₂ indicates a small biquadratic exchange contribution to the magnetic exchange. The temperature dependence of the isomer shifts in Dy₃Fe₅₁₂ gives Mossbauer lattice temperatures of 405 and 505 K for the 16a and 24d sites, respectively, values which are in excellent agreement with the Debye temperature measured for Y₃Fe₅O₁₂.

Recommended Citation

D. Vandormael et al., "Mössbauer Spectral Evidence for Rhombohedral Symmetry in R₃Fe₅O₁₂ Garnets with R = Y, Eu and Dy," Journal of Physics: Condensed Matter, vol. 13, no. 8, pp. 1759 - 1772, Institute of Physics (IOP): Hybrid Open Access, Jun 2001.

The definitive version is available at https://doi.org/10.1088/0953-8984/13/8/312

Department(s)

Chemistry

Keywords and Phrases

Crystal Lattices; Crystal Orientation; Crystal Symmetry; Dysprosium Compounds; Europium Compounds; Garnets; Low Temperature Effects; Magnetization; Mössbauer Spectroscopy; Paramagnetism; Temperature Measurement; Yttrium Compounds; Debye Temperature; Mössbauer Lattice Temperatures; Paramagnetic Spectra; Quadrupole Splittings; Spin Reorientation; Iron Oxides

International Standard Serial Number (ISSN)

0953-8984

Document Type

Article - Journal

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 2001 Institute of Physics (IOP): Hybrid Open Access, All rights reserved.

Publication Date

01 Jun 2001