Experimental Investigation of Phase Equilibria in the R-Fe-Ge Ternary Systems (R= Gd, Er) at 1073K and Magetic Properties of R117Fe52Ge112 | Chapter 2 | Current Perspectives on Chemical Sciences Vol. 6

The interaction between the components was investigated using X-ray powder diraction and scanning electron microscopy energy dispersive X-ray spectroscopy (SEM/EDS) in the R-Fe-Ge (R= Gd, Er) systems at 1073K. There are 19 single-phase regions, 37 two-phase regions, 20 three-phase regions and 19 single-phase regions, 42 two-phase regions and 27 three-phase regions in the isothermal portions of the (Gd, Er) -Fe-Ge ternary phase diagram. Three intermediate solid solutions have been found or verified in the Gd-Fe-Ge diagram: one GdFexGe2 lacunaire (CeNiSi2-type structure space group P6/mmm) and two GdFe4-xGex substitutes (AlB4-type structure space group I4/mmm) and GdFe12-xGex (YCo6Ge6-type structure space group P6/mmm) and one Gd117Fe52Ge112-xGex ternary compound (YCo6Ge6-type structure space group P6/mmm) (Tb117Fe52Ge112-type of structure space group Fm-3m). In the Er-Fe-Ge isothermal section at 800 °C, three ternary compounds were finally confirmed: ErFe4Ge2, Er117Fe52Ge112 and Er0.05Fe0.95Ge and two solid solutions: one ErFexGe2 lacunaire (CeNiSi2-type structure space group P6/mmm) and one ErFe12-xGex (YCo6Ge6-type structure space group P6/mmm). The magnetic susceptibility temperature dependence indicates the magnetic phase transition below, 89 K for Gd117Fe52Ge112 compound and 25K for Er117Fe52Ge112 compound. A deviation from the curie-weiss law was found at lower temperatures and indicated the initiation of a ferro-magnetic magnetic order.

Author(s) Details

M. Jemmali
University of Sfax, Faculty of Science, LSME, BP1171-3018, Sfax, Tunisia and Department of Chemistry, College of Science and Arts, Ar-rass, Qassim University, PO Box 53, Buraydah Postcode, 51921, Saudi Arabia.

S. Walha
Department of Chemistry, College of Science and Arts, Ar-rass, Qassim University, PO Box 53, Buraydah Postcode, 51921, Saudi Arabia.

R. Ben Hassen
Unite de Recherche de Chimie des Matériaux, ISSBAT, Université de Tunis El Manar, 9, Avenue Dr. Zoheir Safi, 1006-Tunis, Tunisia.

H. Noël
Institut des Sciences Chimiques de Rennes, Chimie du Solide et Matériaux, UMR CNRS 6226, Université Rennes 1, Campus de Beaulieu, Bât. 10A, 263 av. Général Leclerc, 35042 Rennes Cedex, France.

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