Hostname: page-component-586b7cd67f-rdxmf Total loading time: 0 Render date: 2024-11-25T17:46:38.203Z Has data issue: false hasContentIssue false
  • English
  • Français

On the Effects of Magnetic Bonding in Rare Earth Transition Metal Interxmetallics

Published online by Cambridge University Press:  28 February 2011

R. Kumar ,
J. Bentley  and
W. B. Yelon
R. Kumar
Affiliation:
Metals and Ceramics Division, Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, TN 37831-6376
J. Bentley
Affiliation:
Metals and Ceramics Division, Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, TN 37831-6376
W. B. Yelon
Affiliation:
University of Missouri Research Reactor, Columbia, MO 65211
Get access

Abstract

Neutron diffraction experiments on rare-earth transition metal magnetic alloys Er2Fe14B and Er2Fe17 have been carried out at temperatures above and below the ordering temperature (Tc). An anomalously large magnetic moment is observed at the crystallographic j2 site in Er2Fe14 B which is the intersection point of the major ligand lines in the crystal structure. The interatomic Fe-Fe distances are in the range of strong ferromagnetic bonds (≥2.66 Å). The analogous f site in Er2Fe17 does not develop as large a magnetic moment. In addition, the same sites show strong preference for Fe atoms in the respective substituted compounds. Due to poor phase stability of Er2 (CoxFe1-x)14 B compounds, iron substitution has been studied in detail in Er2(CoxFe1-x)17 alloys for site specific order and lattice distortion effects. However, a nonlinear change in the c lattice parameter observed in the neutron diffraction results cannot be explained on the basis of site preference alone.

The neutron refinement results indicate iron rich compositions in Er2(CoxFe1-x)17 materials, which is related to random substitution of Fe dumbbell pairs on the rare earth sites in the lattice. However, extensive electron microscopy (selected area electron diffraction and high resolution imaging) of Er2Fe17 and Er2 (Co .40Fe.60)17 failed to reveal any microscopic inhomogeneity. At this stage, the concept of direct negative exchange interaction between dumbbell Fe atom pairs at very short distances of −2.38 A is invoked and its effect is correlated with phase stability. We further suggest that the addition of boron in Er2Fe14B suppresses the substitution of dumbbell Fe pairs as a result of which Tc is raised significantly.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 186: Symposium I – Alloy Phase Stability and Design , 1990 , 445
Copyright
Copyright © Materials Research Society 1991

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

1. Herbst, J. F., Croat, J. J., Pinkerton, F. E., and Yelon, W. B., Phys. Rev., B29, 4176 (1984).Google Scholar
2. Sagawa, M., Fujimura, S., Togawa, M., Yamamoto, H., and Matsuura, Y., J. Appl. Phys. 55, 2083 (1984).Google Scholar
3. Herbst, J. F., Croat, J. J., and Yelon, W. B., J. Appl. Phys. 57, 4086 (1985).Google Scholar
4. Buschow, K. H. J., MRS Symposia on High Performance Permanent Magnets, Vol 96 (1987) (Eds., Herbst, J. F., Koon, N. C., and Sankar, S. G.). J. F. Herbst and W. B. Yelon, J. Appl. Phys., 60(12), 4224 (1986).Google Scholar
5. Pringle, O. A., James, W. J., Yelon, W. B., and Xie, D., personal communication.Google Scholar
6. Thompson, C. W., Mildner, D. F. R., Mehregany, M., Sudol, J., Berliner, R., and Yelon, W. B., J. Appl. Cryst., 17, 385 (1984).Google Scholar
7. Kumar, R., Yelon, W. B., Phys. Rev. B (To be submitted).Google Scholar
8. Yelon, W. B., Xie, D., Hsueh, C. M., Fuerst, C. D., and Meisner, G. P., Phys. Rev., B39, 9389 (1989.)Google Scholar
9. Kumar, R., Yelon, W. B., and Fuerst, C. D., J. Appl. Phys., 63(8), 3725 (1988).Google Scholar
10. Givord, D., Lemaire, R., Moreau, J. M., and Roudaut, E., J. Less Comm. Metals, Vol 29, 361 (1972) [For Lu2 Fe17].Google Scholar
11. Fuerst, C. D. and Herbst, J. F., Appl. Phys. Lett. 54(11), 1068 (1988).Google Scholar
12. Ray, A. E., Sofia, W. A., Blachere, J. R., and Zhang, B., IEEE Trans., Mag–23, No. 5, 2711 (1987).Google Scholar