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Effects induced by chemical non‐stoichiometry and γ‐irradiation on the habit and unit cell parameters of ammonium tetrachlorozincate
Author(s) -
Gaffar M. A.,
ElFadl A. Abu,
Anooz S. Bin
Publication year - 2006
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.200510591
Subject(s) - stoichiometry , chemistry , crystal habit , ammonium , irradiation , crystal structure , crystallography , crystal (programming language) , lattice constant , molar concentration , chemical formula , diffraction , molar ratio , inorganic chemistry , crystallization , organic chemistry , programming language , physics , computer science , nuclear physics , optics , catalysis
The effect of chemical non‐stoichiometry and γ‐irradiation on the unit cell parameters of ammonium tetrachlorozincate (NH 4 ) 2 ZnCl 4 (A 2 ZC 4 ) has been studied. The unit cell parameters of crystal grown from solution with NH 4 Cl/ZnCl 2 molar ratio 1:1, apparently non‐stoichiometrric, are nearly the same as those given for ammonium tetrachlorozincate in the literature. The 2:1 ratio is actually ‘pseudo‐stoichiometric’ due to the hygroscopic nature of ZnCl 2 . The unit cell parameters of crystal grown from solution with molar ratio 2:1 match those of the structure (NH 4 ) 3 ZnCl 5 (A 3 ZC 5 ). The habit of the crystal grown in the former case, from solution with excess ZnCl 2 , was different from that of the crystal grown in the later case, from solution with excess (NH 4 )Cl. Between these two limits, a set of four samples were prepared from solutions with an excess of ZnCl 2 of 20, 30, 60 and 80 wt% in order to detect exact stoichiometric composition to grow A 2 ZC 4 . Analysis by X‐ray diffraction shows that the first two crystals out of this set are mixed from A 2 ZC 4 and A 3 ZC 5 The third and fourth crystals still contain traces of A 3 ZC 5 . Analysis of the X‐ray diffraction was then confirmed by DTA study. Irradiating A 2 ZC 4 with γ‐dose of 250 kGy slightly increased the unit cell volume due to imperfections created by irradiation. Two computer programs were used to calculate the lattice constants and the results were compared. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)