Ternary lanthanoid iron phosphides with YCo5P3 and Zr2Fe12P7-type structures

The new compounds YFe₅P₃ and LnFe₅P₃ (Ln = Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu) were prepared by reaction of the elemental components in a tin flux. They have YCo₅P₃-type structure. A structure refinement of GdFe₅P₃ from single-crystal X-ray data resulted in a conventional residual of R = 0.063 for 29 variable parameters and 693 unique structure factors. Crystals of the new compound Ce₂Fe₁₂P₇ were also prepared by the tin flux technique. Their Zr₂Fe₁₂P₇-type structure was refined to R = 0.029 for 23 variables and 1365 F values. The coordination polyhedra of the two and some other closely related structure types are discussed. The thermal parameters of the transition metal atoms in such structures increase with increasing coordination number.