Mössbauer study of permanent-magnet materials: Sm₂Fe_17-xAl_x compounds

Authors

I.A. Al-Omari, University of Nebraska - Lincoln
Sitaram Jaswal, University of NebraskaFollow
A.S. Fernando, University of Nebraska - Lincoln
David J. Sellmyer, University of Nebraska-LincolnFollow

Date of this Version

November 1994

Comments

Published by American Institute of Physics. J. Applied Physics 76, 6159 (1994). ©1994 American Institute of Physics. Permission to use. http://jap.aip.org/jap/.

Abstract

The Fe⁵⁷ Mössbauer spectra of Sm₂Fe_17-xAl_x, where x=0, 1.0, 2.0, 3.0, and 4.0, have been measured at room temperature and analyzed. The ternary compounds Sm₂Fe_17-xAl_x have the rhombohedral Th₂Zn₁₇ structure. Mössbauer measurements showed that all the compounds studied were ferromagnetic. The average hyperfine field was found to decrease with the increasing aluminum concentration, which is in qualitative agreement with magnetic measurements. The decrease in the average hyperfine field was from 224 kOe at x=0 to 174 kOe at x=4. By fitting the spectra we found that the hyperfine fields for the iron sites decrease in the order 6c, 9d, 18f, and 18h. The measured average isomer shift relative to α-iron was found to increase linearly with x. Analysis of the spectra showed that Al atoms occupy the 6c, 18h, and 18f, but not 9d, Fe sites and the fraction of occupancy of Al was found to depend on x.