Crystal structures of Ca4+x Y3-x Si7O15+x N5-x (0≤ x ≤ 1) comprising of an isolated [Si7 (O,N) 19] unit

Makoto Kobayashi, Takuya Yasunaga, Hideki Kato, Kotaro Fujii, Masatomo Yashima, Masato Kakihana

    Research output: Contribution to journalArticlepeer-review


    Single crystals of the solid solution series Ca 4+x Y 3-x Si 7 O 15+x N 5-x were obtained by a solid-state reaction method using a flux for x = 0, 0.5 and 1, resulting in Ca 4 Y 3 Si 7 O 15 N 5 (tetracalcium triyttrium heptasilicon oxynitride), Ca 4.5 Y 2.5 Si 7 O 15.5 N 4.5 and Ca 5 Y 2 Si 7 O 16 N 4 (pentacalcium diyttrium heptasilicon oxynitride). Single-crystal X-ray analysis revealed that the three compounds are isotypic and belong to space-group type P6 3 /m. Ca 2+ and Y 3+ cations are distributed over two crystallographic sites (site symmetry.. and 1) in a disordered manner. The corresponding (Ca,Y)-centred polyhedra are connected by edge-sharing, resulting in the formation of a layer structure extending parallel to (001). Three [Si(O,N)] 4 tetrahedra (two with point group symmetry m.., one with 3.. and half-occupancy) are condensed into an isolated [Si 7 (O,N) 19 ] unit, in which an [Si(O,N)] 4 tetrahedron is located at the center of a 12-membered oxynitride ring with composition [Si 6 O 15 N 3 ]. The present compounds are the first to have such an [Si 7 (O,N) 19 ] unit in their structures.

    Original languageEnglish
    Pages (from-to)260-263
    Number of pages4
    JournalActa Crystallographica Section E: Crystallographic Communications
    Publication statusPublished - 2019


    • crystal structure
    • oxynitride
    • silicate

    ASJC Scopus subject areas

    • Chemistry(all)
    • Materials Science(all)
    • Condensed Matter Physics


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