The crystal structure of Co2P from X-ray powder diffraction data and its mineralogical applications
Authors:
Skála R, Drábek M
Published in:
Bulletin of Geosciences, volume 76, issue 4;
pages: 209 - 216;
Keywords:
Co2P,
ab initio crystal structure solution from powder data,
phosphide,
schreibersite,
nickelphosphide,
florenskyite,
meteorites,
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Abstract
The structure of stoichiometric Co2P was solved ab initiofrom powder diffraction data. We found the Co2P phase to be orthorhombic, space group
Pnma. Unit-cell dimensions refined from powder data are
a= 5.6479(4),
b = 3.5129(2),
c = 6.6078(4) Å, V= 131.10(1) Å
3, number of formula units in the unit cell Z= 4. All atoms within the structure are located in 4 csites. Phosphorus is nine-coordinated and cobalt atoms are fourand five-coordinated. Structure motifs found in Co
2P are very different from those in members of Fe
3P-Ni
3P solid solution, which may explain the limited miscibility of the title compound in phosphide phases of the schreibersite-nickelphosphide series. Contrary to that, the similarities between the crystal structures of Co
2P and members of the Fe
2P-Ni
2P solid solution invite the interpretation that relatively higher concentrations of Co could be accommodated in barringerite-type phases in meteorites. A complete mutual miscibility can be expected between Co
2P and florenskyite (FeTiP)-like phases, which are isotypic.