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The Spontaneous Strain in an Aluminate Sodalite System Determined by Synchrotron and Sealed Tube X‐radiation
Author(s) -
Melzer R.,
Hu X.,
Pennartz P. U.,
Löchner U.,
Depmeier W.
Publication year - 1991
Publication title -
crystal research and technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.377
H-Index - 64
eISSN - 1521-4079
pISSN - 0232-1300
DOI - 10.1002/crat.2170260822
Subject(s) - sodalite , powder diffractometer , synchrotron radiation , orthorhombic crystal system , tetragonal crystal system , aluminate , synchrotron , diffractometer , crystallography , powder diffraction , materials science , analytical chemistry (journal) , chemistry , diffraction , crystal structure , optics , physics , metallurgy , zeolite , chromatography , cement , catalysis , biochemistry
Lattice parameters in the mixed aluminate sodalite system (Ca 1‐x Sr x ) 8 [Al 12 O 24 ] (CrO 4 ) 2 have been determined on the Aachen/Frankfurt (Darmstadt)/Tübingen powder diffractometer at DESY/Hasylab, Hamburg, FRG, with synchrotron radiation (SR) of a wavelength of γ = 1.383 Å. From these data the values of the spontaneous strain for tetragonal and orthorhombic samples were calculated. The synchrotron data were compared with those obtained by using a conventional Guinier camera with sealed tube CuKα 1 X‐rays. In the mixed system a concentration range Δx of abcut 4 mol%, i.e. in the composition range x from 0.23 to 0.27, exists, in which the conventional technique still indicates cubic symmetry, whereas synchrotron data clearly exhibit tetragonal peak splitting. In order to determine the phase diagrams of mixed aluminate sodalites – or of comparable systems – and to interpret the physical properties of the phases correctly, sealed tube X‐rays are of limited value. Availability of SR beamtime is a crucial factor in the experiments.