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.
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.
Department of Chemistry, College of Science and Arts, Ar-rass, Qassim University, PO Box 53, Buraydah Postcode, 51921, Saudi Arabia.
Unite de Recherche de Chimie des Matériaux, ISSBAT, Université de Tunis El Manar, 9, Avenue Dr. Zoheir Safi, 1006-Tunis, Tunisia.
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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