A Mössbauer effect study of the structural and magnetic properties of Y2(Fe1−xAlx) 14B

Abstract

The crystallographic and magnetic properties of Y2(Fe1−xAlx) 14B, where x equals 0.00, 0.02, 0.04, 0.06, and 0.08, have been investigated by Mössbauer spectroscopy and magnetic measurements at room temperature and 85 K. Magnetic anisotropy and magnetization changes with aluminum substitution indicate that, because of size, the aluminum preferentially occupies the j2 site over the remaining five crystallographically nonequivalent iron sites. This preferential occupation has been confirmed by Mössbauer spectral studies, which indicate that the compositional variation of the hyperfine field for each site is related to the number of near-neighbor aluminum atoms for the site. This compositional variation is helpful in assigning the different spectral components in these alloys as well as in the related Nd2(Fe1−xCox)14B and Y2(Fe1−xCox)14B alloys. In all cases these assignments are consistent with the local symmetry and coordination environment for each site.

Permanent magnets based on R-Fe-B and R-Fe-C alloys

“…The remaining M sites have a fractional occupation of Mn at a concentration below the overall stoichiometry. The preferential occupancy of j 2 sites by manganese was also reported in Y 2 Fe 14−x Mn x B (Sano et al 1989, Marasinghe et al 1991 and Pr 2 Fe 14−x Mn x B (Pringle et al 1990) systems, this also being in agreement with the results of Yang Y C et al (1987).…”

“…Hauet et al (1988a, b) showed by using 57 Fe MS in Nd 2 Fe 14 B-based compounds that Al substitution occurs first in the 8j 2 sites up to concentration corresponding to one substituted atom per cell and further substitution takes place in 16k 2 sites. A preference of Al for 8j 2 sites was also reported by Yang et al (1987), Grössinger et al (1989) and Wiessinger et al (1989). Later, Wiessinger et al (1992) showed that Al in R 2 Fe 13 AlB compounds with R = Gd, Y prefers the 16k 2 sites.…”

“…Their work indicates that although the cobalt avoids the 8j 2 sites, it randomly occupies the remaining five sites. The preference for 8j 2 in Y 2 Fe 14−x Co x B was also reported by Yang Y C et al (1987). showed that iron atoms have a strong preference for occupying the 8j 2 site while the opposite holds for occupying the 16k 2 sites.…”

Magnetic Properties and Magnetic Domain Observation of Nd–Fe–B Sintered Magnets Treated by Grain Boundary Diffusion Process with Dy–Al Co-Sorption

“…Meanwhile, the actual decrease ratio in the remanence was slightly higher than the estimated decrease ratio in the saturation magnetization. The saturation magnetization reportedly decreased due to the substitution of Fe by Al at the j 2 site of the Nd 2 Fe 14 B phase, 33) this may be one reason for the present result.…”