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Refinement of Crystal Structures at Room Temperature and Structural Phase Transitions for (NH 4 ) 4 H 2 (SeO 4 ) 3 and (ND 4 ) 4 D 2 (SeO 4 ) 3 Crystals
Author(s) -
Fukami T.,
Chen R. H.
Publication year - 1999
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/(sici)1521-3951(199908)214:2<219::aid-pssb219>3.0.co;2-l
Subject(s) - crystallography , chemistry , crystal (programming language) , differential scanning calorimetry , deuterium , phase transition , hydrogen bond , crystal structure , phase (matter) , molecule , thermodynamics , physics , organic chemistry , programming language , quantum mechanics , computer science
Differential scanning calorimetry and X‐ray diffraction measurements were performed on tetra‐ammonium dihydrogen triselenate (NH 4 ) 4 H 2 (SeO 4 ) 3 and deuterated tetraammonium dihydrogen triselenate (ND 4 ) 4 D 2 (SeO 4 ) 3 crystals. The phase transition temperatures are found at 377.2(3) and 432.0(1) K for (NH 4 ) 4 H 2 (SeO 4 ) 3 crystal, and at 377.9(8), 427.6(6) and 433.2(1) K for (ND 4 ) 4 D 2 (SeO 4 ) 3 crystal. The detected temperatures above 430 K are confirmed to be the melting points of the crystals. The crystal structures of (NH 4 ) 4 H 2 (SeO 4 ) 3 and (ND 4 ) 4 D 2 (SeO 4 ) 3 are determined at 295 K. The geometric isotope effect for the O–H–O hydrogen bonds caused by the replacement of hydrogen by deuterium is observed in the crystals.