X-ray structural study of intermetallic alloys RT2Si and RTSi2 (R=rare earth, T=noble metal)

Two series of intermetallic alloys, RT2Si and RTSi2, have been synthesized from stoichiometric compositions. The crystal structures of EuPt1+xSi2-x (CeNiSi2-type), CeIr2Si (new structure type), YbPd2Si and YbPt2Si (both YPd2Si-type) have been elucidated from X-ray single crystal CCD data, which were confirmed by XPD experiments. The crystal structures of LaRh2Si and LaIr2Si (CeIr2Si-type), {La,Ce,Pr,Nd}AgSi2 (all TbFeSi2-type), and EuPt2Si (inverse CeNiSi2-type) were characterized by XPD data. RT2Si/RTSi2 compounds were neither detected in as-cast alloys Sc25Pt50Si25, Eu25Os25Si50 and Eu25Rh25Si50 nor after annealing at 900 oC. Instead, X-ray single crystal data prompted Eu2Os3Si5 (Sc2Fe3Si5-type) and EuRh2+xSi2-x (x=0.04, ThCr2Si2-type) as well as a new structure type for Sc2Pt3Si2 (own type). - Graphical abstract: Two series of the intermetallic compounds, RT2Si and RTSi2, have been investigated by X-ray diffraction methods. The new tetragonal CeIr2Si-type of the crystal structure was described and the interrelation between orthorhombic CeNiSi2 and tetragonal CeIr2Si had been discussed as a similar packing of the BaAl4 and AlB2 slabs.