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Non‐crystallographic symmetries in the superstructure of (NH 4 ) 2 ZnCl 4
Author(s) -
Warczewski J.
Publication year - 1980
Publication title -
kristall und technik
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.377
H-Index - 64
eISSN - 1521-4079
pISSN - 0023-4753
DOI - 10.1002/crat.19800150607
Subject(s) - orthorhombic crystal system , homogeneous space , superstructure , crystallography , crystal structure , lattice (music) , lattice constant , space group , group (periodic table) , basis (linear algebra) , materials science , diffraction , chemistry , condensed matter physics , mathematics , x ray crystallography , physics , geometry , thermodynamics , quantum mechanics , acoustics
The modulation vector turned out to be equal 1/4. The lattice constants of the orthorhombic superstructure are determined: a = 12.6197(16) Å, b = 7.2107(81) Å, c = 4 × 9.2746(15) Å. The two of the four absences rules are interpreted as corresponding to the non‐crystallographic symmetries:The space group P 2 1 cn is determined on the basis of the single crystal X‐ray pictures taking into account the experimental evidence of pyroelectricity in (NH 4 ) 2 ZnCl 4 .