3Mg(OH)2·MgSO4·8H2O: A Metastable Phase in the System Mg(OH)2‐MgSO4‐H2O |
| |
| Authors: | Robert E. Dinnebier Melanie Pannach Daniela Freyer |
| |
| Affiliation: | 1. Max Planck Institute for Solid State Research, Heisenbergstrasse 1, 70569 Stuttgart, Germany;2. TU Bergakademie Freiberg, Institute of Inorganic Chemistry, Leipziger Strasse 29, 09596 Freiberg, Germany |
| |
| Abstract: | In the course of investigations relating to magnesia oxysulfate cement the basic magnesium salt hydrate 3Mg(OH)2 · MgSO4 · 8H2O (3–1–8 phase) was found as a metastable phase in the system Mg(OH)2‐MgSO4‐H2O 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 C2/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) Å3]. In the crystal structure of the 3–1–8 phase, parallel double chains of edge‐linked distorted Mg(OH2)2(OH)4 octahedra run along [–110] and [110] direction forming a pattern of crossed rods. Isolated SO4 tetrahedra and interstitial water molecules separate the stacks of parallel double chains. |
| |
| Keywords: | Magnesia cement System Mg(OH)2‐MgSO4‐H2O 3– 1– 8 Phase 5– 1– 2 Phase Powder diffraction Crystal structure Raman spectroscopy Thermal analysis |
|
|
