On the existence and the crystal structure of novel R3TSi3 intermetallic phases (R = rare earth; T = Fe, Co, Ni)

The ternary intermetallic compounds R3NiSi3 (R = La, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Er, Tm), R3FeSi3 (R = Er, Tm) and R3CoSi3 (R = Er) have been synthesized and structurally characterized by X-ray diffraction on powders and single crystals. In particular, within the nickel series, the lighter rare earths (from La to Dy) adopt the orthorhombic Y3NiSi3 structure (ternary, partially ordered variant of the Ta3B4 type), Ho3NiSi3 does not exist, while the heavier rare earths (Er, Tm) crystallize with the monoclinic Sc3NiSi3 type. All the other studied compounds, namely Er3FeSi3, Tm3FeSi3 and Er3CoSi3, occur with the monoclinic Sc3NiSi3 type.