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Tb 3 Sn 7 : polymorphism and crystal structure of high‐temperature modification
Author(s) -
Oshchapovsky Igor,
Pavlyuk Volodymyr,
Chumak Igor
Publication year - 2013
Publication title -
acta crystallographica section b
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.604
H-Index - 33
eISSN - 2052-5206
pISSN - 2052-5192
DOI - 10.1107/s2052519213024378
Subject(s) - crystallography , polyhedron , crystal structure , tin , polymorphism (computer science) , group (periodic table) , structure type , chemistry , space group , diffraction , materials science , x ray crystallography , combinatorics , physics , mathematics , biochemistry , organic chemistry , genotype , gene , optics
During the systematic investigation of the tin‐rich side of the Tb–Sn binary system temperatures of non‐variant transformations were established. The crystal structure of βTb 3 Sn 7 was determined for the first time from single‐crystal diffraction data. Parameters of the unit cell have been determined previously by Manfrinetti & Palenzona [(1993), J. Alloys Compd. 201 , 43–47], but the structure was not solved until now. The compound belongs to a new structure type with space group Pmmm . The unit cell contains two split positions: Sn7 (Wyckoff 1 a ), Sn7 A (Wyckoff 2 q ) and Sn8 (Wyckoff 1 d ), Sn8 A (Wyckoff 2 s ). Structures of both α‐ and β‐modifications of Tb 3 Sn 7 can be described as close packing of the coordination polyhedra of Tb atoms. In turn these polyhedra can be constructed of fragments of simple AuCu 3 and CsCl types.