Different route of hydroxide incorporation and thermal stability of new type of water clathrate: X-ray single crystal and Raman investigation

• Published in: Scientific reports Vol. 7; no. 1; p. 9046
• Main Authors: Dulski, Mateusz, Marzec, Katarzyna M., Kusz, Joachim, Galuskina, Irina, Majzner, Katarzyna, Galuskin, Evgeny
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 22-08-2017; Nature Publishing Group; Nature Portfolio
• Subjects: 140/133; 639/301/930/12; 639/301/930/527/1821; 704/2151/330; Aluminum; Cement; Chlorine; Humanities and Social Sciences; Hydration; Hydrogen bonds; Mineralogy; Minerals; multidisciplinary; Portland cement; Science; Science (multidisciplinary); Single crystals; Symmetry; Thermal stability; Zeolites
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/s41598-017-08152-1

Chlormayenite Ca
12
Al
14
O
32
[♦
4
Cl
2
] (♦-vacancy) is partially hydrated micro porouss mineral with hydroxide groups situated at various crystallographic sites. There are few mechanisms describing its hydration. The first one assumes Cl
−
substitution by OH
−
at the center of the structural cages (
W-
site). The second one determines the converting a
T
1O
4
tetrahedron to a
T
1O
3
(OH)
3
octahedron due to the replacement of oxygen at the
O
2 site by three OH-groups according to the scheme: (
O2
O
2−
 + 
W
Cl
−
) → 3 × 
O
2a
OH. The third mechanism, not considered so far in the case of zeolite-like minerals, includes the hydroxide incorporation in form of hydrogarnet defect due to the arrangement of tetrahedral (OH)
4
in vacant cages. This yields a strong hydrated phase containing even up to 35% of water more than in any currently known mineral applicable to Portland cement. Moreover, water molecules present in different structural cages are stable up to 355 K while dehydroxylation linked to the gradual loss of only 8% of OH
−
groups according to 3
O
2a
OH
−
 → 
O2
O
2−
+
W
OH
−
+
g
H
2
O occurs at temperature range from 355 K to 598 K.