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Crystal structures of Ca4+xY3-xSi7O15+xN5-x (0 ≤ x ≤ 1) comprising of an isolated [Si7(O,N)19] unit.

Authors :
Makoto Kobayashi
Takuya Yasunaga
Hideki Kato
Kotaro Fujii
Masatomo Yashima
Masato Kakihana
Source :
Acta Crystallographica Section E: Crystallographic Communications; Feb2019, Vol. 75 Issue 2, p260-263, 4p
Publication Year :
2019

Abstract

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

Details

Language :
English
ISSN :
20569890
Volume :
75
Issue :
2
Database :
Complementary Index
Journal :
Acta Crystallographica Section E: Crystallographic Communications
Publication Type :
Academic Journal
Accession number :
134590583
Full Text :
https://doi.org/10.1107/S2056989019001257