Ternary rare-earth transition metal phosphides. I. Synthesis and crystal structure of Ho₅Ni₁₉P₁₂

Abstract

Single crystals of the new phosphide Ho₅Ni₁₉P₁₂ were obtained by reacting the elemental components at high temperature. The compound crystallizes in the hexagonal space-group P$\text{6}$2m with the cell constants: a = 12.288 (2), c = 3.762 (2) Å, Z = 1. The structure has been determined from X-ray data and refined to a final R value of 0.049 for 271 independent reflections. It is derivative of the Hf₂Co₄P₃- type structure. Holmium atoms are in a trigonal- prismatic phosphorus coordination while nickel atoms occupy three different phosphorus polyhedra: triangle, tetrahedra and ‘square-planar’ pyramids. The atomic arrangement of Ho₅Ni₁₉P₁₂ appears as a combination of those observed in Zr₂Fe₁₂P₇ and Zr₆Ni₂₀P₁₃-type structures.