Thermal collapse of SAPO-34 molecular sieve towards a perfect glass

Autor:	Thangaraj Selvam, Andreas Kuhnt, Lothar Wondraczek, Dimitrios Palles, Guojun Gao, Doris Möncke, Efstratios I. Kamitsos, Wilhelm Schwieger
Rok vydání:	2013
Předmět:	Crystallography Materials science Chemical physics Thermal Materials Chemistry Ceramics and Composites Thermal aging Condensed Matter Physics Molecular sieve Zeolite Amorphous phase Electronic Optical and Magnetic Materials Amorphous solid
Zdroj:	Journal of Non-Crystalline Solids. 360:36-40
ISSN:	0022-3093
DOI:	10.1016/j.jnoncrysol.2012.10.001
Popis:	Controlled collapse of a silicoaluminophosphate molecular sieve CHA-type SAPO-34 by thermal aging was studied in a multi-method approach. Structural changes and the mechanism of order–disorder–order transitions during collapse were followed for varying annealing conditions between 1000 and 1100 °C. Collapse of SAPO-34 occurs via the formation of an intermediate amorphous state by the loss of long-range order but preservation to a high degree of short-range order and macroscopic morphology. This intermediate amorphous state with low entropy may be classified as a “perfect glass”. Prolonged aging in the collapse regime results in the precipitation of crystalline AlPO 4 while the SiO 2 species initially remain in an amorphous phase. Further increasing the aging temperature leads to virtually complete recrystallization and, ultimately, melting.
Databáze:	OpenAIRE
Externí odkaz:	https://explore.openaire.eu/search/publication?articleId=doi_________::4fcd5cc5d0ac54f85d772b3881241fb2 https://doi.org/10.1016/j.jnoncrysol.2012.10.001 Zobrazit plný text záznamu Full Text from ScienceDirect