Landolt-Börnstein - Group III Condensed Matter

7.2.4.2 Preparation, crystal structure and lattice parameters

Abstract

This chapter provides an introduction on R2Fe14C-type magnet alloys. The study of R-Fe-B alloys, where R is a rare-earth element, has received considerably attention, since permanent magnets produced from these materials surpass those of rare-earth-cobalt type. The preparation of R2Fe14C materials is relatively easy if R is a heavy rare-earth element. It also discusses crystal structure and lattice parameters of R2Fe14C-type magnet alloys. Although the R2Fe14C compounds are stable at room temperature for all rare-earth elements, there are some difficulties in their formation for the first few members of the series when normal casting is applied. The difficulty is associated with a solid-state transformation at which R2Fe14C decomposes at high temperatures into R2Fe17Cx compounds. The transformation temperatures can be influenced to some extent by partial substitutions of Fe or C. The transformation temperatures in R2Fe14C compound are shown. The R2Fe14C compounds crystallize in a tetragonal structure having P42/mnm space group. The atomic sites in Lu2Fe14C at 295 K, lattice parameters of R2Fe14C-based compounds, lattice parameters and relative change in volume upon hydrogenation for R2Fe14C-based hydrides, lattice parameters of (R'R")Fe14C compounds, and R2Fe14C-based mixed borides and carbides at room temperature are tabulated. Maximum value of the hydrogen uptake ymax and increment in the Curie temperature upon hydrogenation of R2Fe14C and R2Fe14B compounds, variation of the lattice parameter as function of the lattice parameter for R2Fe14C compounds before and after hydrogenation, and composition dependence of the lattice parameters for R1Fe14-xMnxC compounds with R = Ce, Pr, Ho and Er are figured out.

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Title
7.2.4.2 Preparation, crystal structure and lattice parameters
Book Title
Magnetic Alloys for Technical Applications. Hard Magnetic Alloys
In
7.2.4 R{2}Fe{14}C-type magnet alloys
Book DOI
10.1007/b41058
Chapter DOI
10.1007/10028076_47
Part of
Landolt-Börnstein - Group III Condensed Matter
Volume
19I2
Editors
  • H. P. J. Wijn
  • Authors
  • E. Burzo
  • H. R. Kirchmayr
  • Cite this content

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