X-RAY-, DTA- AND THERMO-MAGNETICAL ANALYSIS OF Y, SM, GD, DY, HO, ER-MN-COMPOUNDS

A summary of the phases is presented which occur in the systems Gd, Sm, Dy, Ho, Er-Mn. In all these systems the phases REMn2, REMn4 (RE6Mn23 or REMn5) and REMn12 exist (the compound SmMn12 has, up to now, not been detected). The phases HoMn2 and ErMn2 possess (at least at room temperature) the same structure (MgCu2) as the other REMn2 compounds. The lattice spacings of the compounds diminish continously with atomic number. By DTA the systems Gd-Mn and Dy-Mn have been studied and phase diagrams constructed. The X-ray investigations and X-ray fluorescence analysis agree with these diagrams. Magnetic measurements with Y, Sm, Dy, Ho and Er-Mnx (x = 3, 83 - 5) yielded accurate Curie-points. The saturation magnetization of YMn5 and SmMn5 is higher than the values of literature. By measurements of the paramagnetic properties of SmMn5 and HoMn5 above the Curie temperature the fact that these compounds are ferrimagnetic and not ferromagnetic could be established. The results are discussed in terms of the theory of ferrimagnetic substances.
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