Skip to Main Content
Skip Nav Destination

Dehydration and rehydration processes in gmelinite; an in situ X-ray single-crystal study

Alberto Alberti, Ilaria Parodi, Giuseppe Cruciani, Maria Chiara Dalconi and Annalisa Martucci
Dehydration and rehydration processes in gmelinite; an in situ X-ray single-crystal study
American Mineralogist (November 2010) 95 (11-12): 1773-1782


The dehydration-rehydration process in gmelinite-Na Na (sub 7.27) K (sub 0.28) Ca (sub 0.15) (H (sub 2) O) (sub 21.85) [Al (sub 7.71) Si (sub 17.24) O (sub 48) ]-GME, a natural zeolite that can be described as a parallel stacking of double six rings of tetrahedra in the AABB sequence, was studied by X-ray diffraction data. Its space group is P6 (sub 3) /mmc with a=13.764(1) and c=10.078(1) Aa cell parameters. Single-crystal data collections were performed at room conditions and at increasing temperatures, in a hot nitrogen stream, up to the fragmentation of the crystals, which occurs at a temperature as low as 100 degrees C, and afterward the crystal was cooled down to room conditions. X-ray powder diffraction data showed that gmelinite-Na transforms into a new structure with an AFI-type topology at about 300 degrees C. At room conditions, extraframework cations are located in two symmetrically independent positions, both of which are coordinated to either framework O atoms or water molecules. When the mineral is heated to 90 degrees C, about 40% of H (sub 2) O is lost, and one cation site splits over two positions, which are three-coordinated to the framework O atoms. The dehydration process is completely reversible over a period of hours. X-ray single-crystal data has highlighted that gmelinite-Na when quenched at 100 K displays remarkable modifications in its extraframework content, resulting in a strong disorder in its extraframework ions. As in the case of heating, the mineral restores its structural features when brought back to room temperature.

ISSN: 0003-004X
EISSN: 1945-3027
Serial Title: American Mineralogist
Serial Volume: 95
Serial Issue: 11-12
Title: Dehydration and rehydration processes in gmelinite; an in situ X-ray single-crystal study
Affiliation: Universita di Ferrara, Dipartimento di Scienze della Terra, Ferrara, Italy
Pages: 1773-1782
Published: 201011
Text Language: English
Publisher: Mineralogical Society of America, Washington, DC, United States
References: 33
Accession Number: 2011-002405
Categories: Mineralogy of silicates
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 7 tables
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Abstract, copyright, Mineralogical Society of America. Reference includes data from GeoScienceWorld, Alexandria, VA, United States
Update Code: 201102
Close Modal

or Create an Account

Close Modal
Close Modal