Landolt-Börnstein - Group III Condensed Matter Introduction


This chapter provides a general introduction to the discussion on rare-earth-iron interstitial compounds. The compounds can be formed for all lanthanides except lanthanum. This series of compounds is perhaps most notable for their low Curie temperatures Tc. The Fe magnetic moments in R2Fe17 compounds are almost as large as those in iron metals. The interactions between Fe atoms situated at distances greater than ≈ 2.45 Å are positive. The negative interactions between Fe atoms are not satisfied since they are smaller than the positive ones and consequently a considerable magnetic energy is stored. This brings about the low ordering temperatures of the above compounds. In 1987 worldwide efforts have started to investigate the magnetic properties of RFe11M with M = Ti, V, intending to provide a new alloy for use in permanent magnets. Among them, the SmFe11Ti compound seems to be the most potential candidate. However, on the basis of experiments up to date, the SmFe11Ti compound appears to offer less practical use in permanent magnet development. The reasons for this are two-fold: (1) its Curie temperature is rather small and (2) the saturation magnetization is lower than for other permanent magnet materials such as R2Fe14B. The absorption of nitrogen in RFe11Ti not only increases the Curie temperature and saturation magnetization, but also gives rise to profound changes of the magnetocrystalline anisotropy. One significant result of these changes is that NdFe11TiNx as well as other related compounds now emerge as novel powerful permanent magnet materials.

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Title Introduction
Book Title
Magnetic Alloys for Technical Applications. Hard Magnetic Alloys
In General
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Landolt-Börnstein - Group III Condensed Matter
  • H. P. J. Wijn
  • Authors
  • E. Burzo
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