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The Crystal Structures of SrAlF 5 and Ba 0.43(1) Sr 0.57(1) AlF 5
Author(s) -
Kubel Frank
Publication year - 1998
Publication title -
zeitschrift für anorganische und allgemeine chemie
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.354
H-Index - 66
eISSN - 1521-3749
pISSN - 0044-2313
DOI - 10.1002/(sici)1521-3749(199809)624:9<1481::aid-zaac1481>3.0.co;2-f
Subject(s) - tetragonal crystal system , crystallography , crystal structure , octahedron , chemistry , luminescence , space group , dimer , superstructure , materials science , x ray crystallography , diffraction , physics , optoelectronics , organic chemistry , optics , thermodynamics
Two members belonging to the pseudobinary phase diagram of Ba/SrF 2 and AlF 3 were synthesized. Single domain crystals of SrAlF 5 and Ba 0.43(1) Sr 0.57(1) AlF 5 were prepared from the corresponding metal fluorides. The mixed compound Ba 0.43(1) Sr 0.57(1) AlF 5 has been synthesized and characterized in detail for the first time. The structure of SrAlF 5 was reinvestigated; a superstructure was found which is absent in Ba 0.43(1) Sr 0.57(1) AlF 5 . The compounds crystallize at room temperature in the centrosymmetric tetragonal space groups I 4 1 / a and I 4/ m . Lattice parameters are a = b = 1988.22(14), c = 1432.24(19) and a = b = 1431.32(14), c = 722.83(7) pm. Both structures differ mainly in the AlF 6 arrangement situated in the cavities of the matrix structure. In SrAlF 5 , ordered dimer [Al 2 F 10 ] 4– units are found, whereas in the Ba 2+ mixed sample a linear chain of AlF 6 octahedra is observed. For both compounds no partial occupation was observed. Sm 2+ doped samples are further characterized by luminescence measurements. Four independent sites of alkaline earth atoms were found in the Sm 2+ luminescence of the host SrAlF 5 .