Cr23C6 is the prototypical compound of a common crystal structure, discovered in 1933[1] as part of the chromium-carbon binary phase diagram. Over 85 known compounds adopt this structure type,[2] which can be described as a NaCl-like packing of chromium cubes and cuboctahedra.[3]
The Cr23C6 structure represented as polyhedra of atoms. The blue surfaces outline cuboctahedra of chromium atoms, whereas the red surfaces outline chromium cubes capped by carbon atoms. The darker blue spheres represent chromium atoms outside of the polyhedra.
The shortest interatomic distances are between carbon and chromium atoms, which is expected on the basis of atomic size. The carbon atoms are in positions that cap each face of the chromium cubes and their coordination environment can be thought of as distorted square antiprisms formed from chromium atoms of both the cubes and the cuboctahedra.
The closest Cr-Cr contacts are between members of a cuboctahedron, and the third closest are between members of a cube. The members of the cube, however, are closer to the 8 chromium atoms in the unit cell that are not part of either polyhedron. The coordination environment of these other atoms can be thought of as distorted Friauf polyhedra composed of chromium atoms, if next-nearest neighbors are included.
Materialsedit
Examples of compounds that form in this structure type include Cr23C6, Mn23C6, and many ternary intermetallic carbides and borides.[4] A few phases of ternary silicides, germanides, and phosphides are also known to exist.[5][6] In going from the binary to ternary systems, some of the transition metal atoms are substituted by a third element, which can be an alkali metal, alkaline earth metal, rare-earth element, main group element, or another transition metal. This leads to an empirical formula of the form A23−xBxC6. Materials of this kind continue to be studied for potentially interesting magnetic and physical properties.[7][8]
Referencesedit
^Westgren, A. Crystal structure and composition of cubic chromium carbide. Jernkontorets Ann.1933,117, 501.
^Villars, P. Pearson's Handbook of Crystallographic Data for Intermetallic Phases, vol. 1; ASM International: Materials Park, 1997.
^Bowman, A. L.; Arnold, G. P.; Storms, E. K.; Nereson, N. G. (1972-10-15). "The crystal structure of Cr23C6". Acta Crystallographica Section B: Structural Crystallography and Crystal Chemistry. 28 (10). International Union of Crystallography (IUCr): 3102–3103. doi:10.1107/s0567740872007526. ISSN 0567-7408.
^Stadelmaier, H. H. Developments in the Structural Chemistry of Alloy Phases; Plenum Press: New York, 1969; p 141.
^Gribanov, A.V.; Seropegin, Yu.D.; Bodak, O.I. (1994). "Crystal structure of the compounds Ce3Pd20Ge6 and Ce3Pd20Si6". Journal of Alloys and Compounds. 204 (1–2). Elsevier BV: L9–L11. doi:10.1016/0925-8388(94)90057-4. ISSN 0925-8388.
^Keimes, V.; Mewis, A. (1992). "Mg3Ni20P6 und Mn3Ni20P6 - Zwei neue Phosphide mit Cr23C6-Struktur" [Mg3Ni20P6 and Mn3Ni20P6 - Two new phosphides with the Cr23C6 structure]. Zeitschrift für anorganische und allgemeine Chemie (in German). 618 (12). Wiley: 35–38. doi:10.1002/zaac.19926180107. ISSN 0044-2313.
^Eriksson, T.; Vennström, M.; Ronneteg, S.; Andersson, Y.; Nordblad, P. (2007). "Complex magnetic properties of Mn3Ni20P6 and ferromagnetic structure of the new isostructural compound Mn3Pd20P6". Journal of Magnetism and Magnetic Materials. 308 (2). Elsevier BV: 203–209. doi:10.1016/j.jmmm.2006.05.016. ISSN 0304-8853.
^Veremchuk, I.; Gumeniuk, R.; Prots, Yu.; Schnelle, W.; Burkhardt, U.; Rosner, H.; Kuz'ma, Yu.; Leithe-Jasper, A. (2009). "Crystallographic and physical properties of RE2−xNi21B6 (RE=Er, Yb and Lu)". Solid State Sciences. 11 (2). Elsevier BV: 507–512. doi:10.1016/j.solidstatesciences.2008.09.004. ISSN 1293-2558.
External linksedit
International Crystal Structure Database
May 04, 2024
crystal, structure, cr23c6, prototypical, compound, common, crystal, structure, discovered, 1933, part, chromium, carbon, binary, phase, diagram, over, known, compounds, adopt, this, structure, type, which, described, nacl, like, packing, chromium, cubes, cubo. Cr23C6 is the prototypical compound of a common crystal structure discovered in 1933 1 as part of the chromium carbon binary phase diagram Over 85 known compounds adopt this structure type 2 which can be described as a NaCl like packing of chromium cubes and cuboctahedra 3 The Cr23C6 structure represented as polyhedra of atoms The blue surfaces outline cuboctahedra of chromium atoms whereas the red surfaces outline chromium cubes capped by carbon atoms The darker blue spheres represent chromium atoms outside of the polyhedra Contents 1 Structure 2 Materials 3 References 4 External linksStructure editThe space group of this structure is called Fm3 m in Hermann Mauguin notation or 225 in the International Tables for Crystallography It belongs to a cubic crystal system with Pearson symbol cF116 The shortest interatomic distances are between carbon and chromium atoms which is expected on the basis of atomic size The carbon atoms are in positions that cap each face of the chromium cubes and their coordination environment can be thought of as distorted square antiprisms formed from chromium atoms of both the cubes and the cuboctahedra The closest Cr Cr contacts are between members of a cuboctahedron and the third closest are between members of a cube The members of the cube however are closer to the 8 chromium atoms in the unit cell that are not part of either polyhedron The coordination environment of these other atoms can be thought of as distorted Friauf polyhedra composed of chromium atoms if next nearest neighbors are included Materials editExamples of compounds that form in this structure type include Cr23C6 Mn23C6 and many ternary intermetallic carbides and borides 4 A few phases of ternary silicides germanides and phosphides are also known to exist 5 6 In going from the binary to ternary systems some of the transition metal atoms are substituted by a third element which can be an alkali metal alkaline earth metal rare earth element main group element or another transition metal This leads to an empirical formula of the form A23 xBxC6 Materials of this kind continue to be studied for potentially interesting magnetic and physical properties 7 8 References edit Westgren A Crystal structure and composition of cubic chromium carbide Jernkontorets Ann 1933 117 501 Villars P Pearson s Handbook of Crystallographic Data for Intermetallic Phases vol 1 ASM International Materials Park 1997 Bowman A L Arnold G P Storms E K Nereson N G 1972 10 15 The crystal structure of Cr23C6 Acta Crystallographica Section B Structural Crystallography and Crystal Chemistry 28 10 International Union of Crystallography IUCr 3102 3103 doi 10 1107 s0567740872007526 ISSN 0567 7408 Stadelmaier H H Developments in the Structural Chemistry of Alloy Phases Plenum Press New York 1969 p 141 Gribanov A V Seropegin Yu D Bodak O I 1994 Crystal structure of the compounds Ce3Pd20Ge6 and Ce3Pd20Si6 Journal of Alloys and Compounds 204 1 2 Elsevier BV L9 L11 doi 10 1016 0925 8388 94 90057 4 ISSN 0925 8388 Keimes V Mewis A 1992 Mg3Ni20P6 und Mn3Ni20P6 Zwei neue Phosphide mit Cr23C6 Struktur Mg3Ni20P6 and Mn3Ni20P6 Two new phosphides with the Cr23C6 structure Zeitschrift fur anorganische und allgemeine Chemie in German 618 12 Wiley 35 38 doi 10 1002 zaac 19926180107 ISSN 0044 2313 Eriksson T Vennstrom M Ronneteg S Andersson Y Nordblad P 2007 Complex magnetic properties of Mn3Ni20P6 and ferromagnetic structure of the new isostructural compound Mn3Pd20P6 Journal of Magnetism and Magnetic Materials 308 2 Elsevier BV 203 209 doi 10 1016 j jmmm 2006 05 016 ISSN 0304 8853 Veremchuk I Gumeniuk R Prots Yu Schnelle W Burkhardt U Rosner H Kuz ma Yu Leithe Jasper A 2009 Crystallographic and physical properties of RE2 xNi21B6 RE Er Yb and Lu Solid State Sciences 11 2 Elsevier BV 507 512 doi 10 1016 j solidstatesciences 2008 09 004 ISSN 1293 2558 External links editInternational Crystal Structure Database Retrieved from https en wikipedia org w index php title Cr23C6 crystal structure amp oldid 1197271813, wikipedia, wiki, book, books, library,
