Phase stability, structure and magnetic properties of R-3(Fe,TM)(29), (R=Gd, Dy, Er, Y and TM=V, Ti) compounds with disordered structures

The R-3(Fe,V)(29) compounds, with R=Dy, Er, Y, and the Gd-3(Fe, TM)(29), wi th TM=Ti and V, after heat treatment between 1123 and 1233 K form disordere d structures that belong in the CaCu5 type family. The compounds with R=Y o r Dy and TM=V crystallize in a disorder CaCu5 structure type (space group ( S.G.): P61mmm with cell dimensions a=4.8769(1) Angstrom, c=4.1729(3) Angstr om and a=4.8692(2) Angstrom, c=4.1750(3) Angstrom, respectively), with main structural characteristic the substitutional disorder observed at the R cr ystallographic site. The same structure is formed from the Gd-3(Fe,Ti)(29) when it is annealed at 1123 K (a=4.9044 Angstrom, c=4.1920 Angstrom). The c ompounds with R=Gd (TM=V) crystallizes in a disordered Th2Zn17 structure ty pe (S.G.: R-3m, a=8.5197(3) Angstrom and c=12.481(1) Angstrom) and with R=E r in a disordered Th2Ni17 structure type (S.G.: P6(3)lmmc, a=8.4142(6) Angs trom and c=8.3319(7) Angstrom). A structural study of the Y-3(Fe,V)(29) com pound based on time of flight. high resolution neutron powder diffraction d ata is presented. The magnetocrystalline anisotropy is of an easy plane typ e at room temperature for all the examined compounds, (C) 2001 Elsevier Sci ence B.V. All rights reserved.