Tyrrellite, a naturally occurring Co-Ni-Cu selenide, has been studied by single-crystal X-ray diffraction. It possesses the normal spinel-type structure, with Cu occupying the tetra-hedral site and (Co+Ni) the octa-hedral site. The average Cu - Se distance of 2.3688 (2) Å is close to that of 2.3703 (8) Å in CuCr2Se4, whereas the average (Co+Ni) - Se distance of 2.3840 (1) Å appears to be slightly shorter than most octa-hedral Co - Se or Ni - Se distances (2.40-2.50 Å) in other selenides. The refined structure provides a basis for a redefinition of the ideal chemical formula of tyrrellite, which should be Cu(Co,Ni)2Se4, rather than the previously suggested (Cu,Co,Ni)3Se4.
|Original language||English (US)|
|Journal||Acta Crystallographica Section C: Crystal Structure Communications|
|State||Published - Jun 14 2007|
ASJC Scopus subject areas
- Biochemistry, Genetics and Molecular Biology(all)