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Phase transitions and twinned low‐temperature structures of tetraethylammonium tetrachloridoferrate(III)
Author(s) -
Lutz Martin,
Huang Yuxing,
Moret MarcEtienne,
Klein Gebbink Robertus J. M.
Publication year - 2014
Publication title -
acta crystallographica section c
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.304
H-Index - 17
ISSN - 2053-2296
DOI - 10.1107/s2053229614007955
Subject(s) - crystal twinning , orthorhombic crystal system , crystallography , hexagonal crystal system , polar , group (periodic table) , phase (matter) , materials science , crystal structure , chemistry , microstructure , physics , organic chemistry , astronomy
The title compound, [(C 2 H 5 ) 4 N][FeCl 4 ], has at room temperature a disordered structure in the high‐hexagonal space group P 6 3 mc . At 230 K, the structure is merohedrally twinned in the low‐hexagonal space group P 6 3 . The volume has increased by a factor of 9 with respect to the room‐temperature structure. At 170 and 110 K, the structure is identical in the orthorhombic space group Pca 2 1 and twinned by reticular pseudomerohedry. The volume has doubled with respect to the room‐temperature structure. All three space groups, viz. P 6 3 mc , P 6 3 and Pca 2 1 , are polar and the direction of the polar axis is not affected by the twinning. In the P 6 3 and Pca 2 1 structures, all cations and anions are well ordered.