Equiatomic ternary rare earth-transition metal silicides, germanides and gallides

TLDR: In this article, the occurrence and structural features of these five structure types together with the tetragonal PbFCl type, an Fe2As-type derivative found earlier for RFeSi and RCoSi compounds were discussed.

Abstract: Over 100 new equiatomic ternary rare earth (R)-transition metal (T) silicides, germanides and gallides were synthesized and structurally analysed either by evaluating powder diffraction photographs or in the case of ScRhSi, ScPtSi, YNiSi, ScRuGe and PrPtGe by refining single-crystal diffraction data. The hexagonal ZrNiAl type, an Fe2P-type derivative, was found for ScRuSi and ScTGe (T ≡ Ru, Rh, Pd, Os). The orthorhombic TiNiSi type, a PbCl2-type derivative, was assigned to RRhGa (R ≡ Er, Y), RPdGa (R ≡ La, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Tm, Lu, Y, Sc), RIrGa (R ≡ Er, Y), RPtGa (R ≡ La, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Y, Sc), YNiSi, RRhSi (R ≡ Er, Y, Sc), ScPdSi, RIrSi (R ≡ Gd, Er, Y, Sc), RPtSi (R ≡ Tb, Dy, Ho, Er, Tm, Lu, Y, Sc), RRhGe (R ≡ Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Tm, Y, Sc), RIrGe (R ≡ Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Tm, Y, Sc) and RPtGe (R ≡ Sm, Gd, Tb, Dy, Ho, Er, Tm, Y, Sc). The CeCu2 type, which is related to TiNiSi, was found for R(Pd0.5Ge0.5)2 (R ≡ La, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Tm, Y) and R(Pt0.5Ge0.5)2 (R ≡ Ce, Pr, Nd) where the palladium or platinum and germanium atoms are arranged at random on the copper sites. The tetragonal LaPtSi type, a ThSi2-type derivative, was found for RPtSi (R ≡ La, Ce, Pr, Nd, Sm, Gd), LaIrGe and LaPtGe. Finally the cubic LaIrSi type, an SrSi2-type derivative, was found for LaIrSi. The occurrence and structural features of these five structure types together with the tetragonal PbFCl type, an Fe2As-type derivative found earlier for RFeSi and RCoSi compounds, are discussed.