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3Mg(OH) 2 ·MgSO 4 ·8H 2 O: A Metastable Phase in the System Mg(OH) 2 ‐MgSO 4 ‐H 2 O
Author(s) -
Dinnebier Robert E.,
Pannach Melanie,
Freyer Daniela
Publication year - 2013
Publication title -
zeitschrift für anorganische und allgemeine chemie
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.354
H-Index - 66
eISSN - 1521-3749
pISSN - 0044-2313
DOI - 10.1002/zaac.201300128
Subject(s) - octahedron , crystallography , hydrate , metastability , phase (matter) , crystal structure , raman spectroscopy , powder diffraction , x ray crystallography , diffraction , crystal (programming language) , infrared spectroscopy , magnesium , molecule , materials science , chemistry , physics , optics , programming language , organic chemistry , computer science , metallurgy
In the course of investigations relating to magnesia oxysulfate cement the basic magnesium salt hydrate 3Mg(OH) 2 · MgSO 4 · 8H 2 O (3–1–8 phase) was found as a metastable phase in the system Mg(OH) 2 ‐MgSO 4 ‐H 2 O at room temperature (the 5–1–2 phase is the stable phase) and was characterized by thermal analysis, Raman spectroscopy, and X‐ray powder diffraction. The complex crystal structure of the 3–1–8 phase was determined from high resolution laboratory X‐ray powder diffraction data [space group C 2/ c , Z = 4, a = 7.8956(1) Å, b = 9.8302(2) Å, c = 20.1769(2) Å, β = 96.2147(16)°, and V = 1556.84(4) Å 3 ]. In the crystal structure of the 3–1–8 phase, parallel double chains of edge‐linked distorted Mg(OH 2 ) 2 (OH) 4 octahedra run along [–110] and [110] direction forming a pattern of crossed rods. Isolated SO 4 tetrahedra and interstitial water molecules separate the stacks of parallel double chains.