Reduced Ternary Rare‐Earth–Transition Metal Tellurides for the Smaller Rare‐Earth Elements. An Exploration and an Explanation of the Marked Stability Differentiation among the Rare‐Earth Elements in These Phases

The existence of further metal‐rich condensed cluster compounds in R – Z –Te systems has been synthetically explored for R = Sc, Y, Pr, Dy, Er, Tm, Yb, Lu and, mainly, Z = Ru, Rh, Pd, Ag, Ir, Pt, Au. Ten new examples of orthorhombic Er 7 Ni 2 Te 2 ‐type ( Imm 2) have been identified and that for Dy 7 Ir 2 Te 2 has been refined. Seven new examples of other ternary structure types plus X‐ray powder pattern evidence for 14 unknown phases have also been identified. To date the family of ternary R – Z –Te phases appears to be limited to those for R = Sc, Y, and Dy–Lu, a trend that is parallel to but more emphatic than those variations found among parallel cluster halide systems. Stability trends among the halide and especially the telluride series follow the I1 + I2 sums for the R elements well, the larger values of which are considered to reflect better mixing of R and Z valence d orbitals in the more stable phases.