Rare-earth-cobalt magnets

T. Ojima and co-workers, / Appl Phjs. 16, 671 (1977) IEEE Trans. Mag. 13, 1317 (1977) K. J. Stmat, ed.. Proceedings 3rd International Workshop on Rare Earth-Cobalt Permanent Magnets, University of Dayton, Ohio, 1978, p. 406. 

K. J. Stmat, ia Proceedings 4th International Workshop on Rare Earth-Cobalt Permanent Magnets, Society Non-Traditional Technology, Tokyo, 1979, p. 8. 

K. Halbach 1980, (Design of permanent multipole magnets with oriented rare earth cobalt material), Nud. Instrum. Meth. 169, 1-10. 

Typical domain walls are smooth and extend over many interatomic distances. However, deviations from this continuum picture occur in very hard materials (narrow walls), at grain boundaries and in the case of geometrical constraints. Narrow-wall phenomena, which have been studied for example in rare-earth cobalt permanent magnets [189] and at grain boundaries [95, 96], involve individual atoms and atomic planes and lead to comparatively small corrections to the extrinsic behavior. 

Kundu, A., Sarkar, R., Pahari, B., Ghoshray, A. Rao, C. N. R, 2007 A comparative study of the magnetic properties and phase separation behavior of the rare earth cobaltates, Liyl5Sro Co03 (Lre=rare earth), J. Solid State Chem. 180, 1318-1324. (doi 10.1016/j.jssc.2007,02.003)... 

Stmat KJ (1988) Rare earth-cobalt permanent magnets. In Wohlfarth EP, Buschow KHJ (Eds.) Eerromagnetic materials, vol 4. North-HoUand, Amsterdam, p 131... 

Workshop on Rare Earth-Cobalt Permanent Magnets, eds X.-S. Pan, W.-W. Ho and C.-Z. Yu (China Academic Publishers, Beijing, China) p. 339. 

Fig. 2. The rare-earth elements now used in rare earth-cobalt permanent magnets, their effect on magnet properties (referenced to Sm alloy), and relative cost of the rare earth component.

Kaneko, H., and T. Kurino, eds, 1979, Proc. 4th Int. Workshop on Rare Earth-Cobalt Permanent Magnets and their Applications, Hakone... 

Strnat, K. J. (1988). Rare earth-cobalt permanent magnets. In Ferromagnetic Materials, Vol. 4. Eds. E. P. Wohifarth and K. H. J. Buschow. North-Holland, Amsterdam, pp. 131-209. 

Stmat, K.J., 1976, in Proc. 2nd Int. Workshop on Rare-earth Cobalt Permanent Magnets and their Applications, Dayton, OH, p. 1. 

It is well known that crystalline rare-earth-cobalt phases lend themselves fairly well to permanent magnet applications. Materials related to SmCoj are currently reported to offer energy products higher than 340 kJ m". The manufacturing costs are still appreciable, and have prevented large scale applications. This has led to a search for less expensive materials based on the less expensive Fe rather than on Co. All these attempts have failed thus far since the crystalline phases studied do not have the required type of magnetocrystalline anisotropy and coercive forces are generally low. 

In addition to the Kirchmayr-Poldy review, additional information concerning the magnetic behaviors of rare earth compounds are found in the reviews by Buschow (1977, 1979), Nesbitt and Wernick (1973), Taylor and Darby (1972) and Wallace (1973). The review by Nesbitt and Wernick is exclusively on rare-earth-cobalt permanent magnets, while the others generally cover a wide range of compounds. 

---