Substitution clustering in a non-stoichiometric celsian synthesized by the thermal transformation of barium exchanged zeolite X

Journal Article · Sat Jul 15 00:00:00 EDT 2006 · Journal of Solid State Chemistry

DOI:https://doi.org/10.1016/j.jssc.2006.03.021· OSTI ID:20905336

Clayden, Nigel J ^[1]; Esposito, Serena ^[2]; Ferone, Claudio ^[2]; Pansini, Michele ^[2]

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1. School of Chemical Sciences and Pharmacy, University of East Anglia, NR4 7TJ (United Kingdom)
2. Laboratorio Materiali del Dipartimento di Meccanica, Strutture, Ambiente e Territorio, Facolta di Ingegneria dell'Universita di Cassino, Via G. Di Biasio 43, 03043 Cassino (FR) (Italy)

The thermal transformation of Ba exchanged zeolite X to celsian has been studied by {sup 27}Al and {sup 29}Si MAS NMR spectroscopy. Evidence for the degradation of the zeolite framework is present in the {sup 29}Si NMR spectra after thermal treatment at 850 deg. C. Confirmation is provided by the {sup 29}Si NMR data that synthesis of celsian via the decomposition of Ba exchanged zeolite leads to a single defect phase. Clustering of the isomorphous replacement of aluminium by silicon must occur to explain the observed {sup 29}Si chemical shifts. The {sup 27}Al NMR data show distorted aluminium co-ordination sites upon the thermal transformation of Ba exchanged zeolite X. The distortions present in the amorphous matrix are greater than those present in the monoclinic and hexagonal crystalline phases of celsian. - Graphical abstract: Monte Carlo simulation of the Q {sub 4}(mAl) silicon connectivity in the {alpha}-hexagonal celsian lattice, for a Si/Al ratio of 1:1. Si atoms are shown in yellow and the Al atoms in black.

• OSTI ID: 20905336
• Journal Information: Journal of Solid State Chemistry, Vol. 179, Issue 7; Other Information: DOI: 10.1016/j.jssc.2006.03.021; PII: S0022-4596(06)00169-1; Copyright (c) 2006 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved; Country of input: International Atomic Energy Agency (IAEA); ISSN 0022-4596
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
CHEMICAL SHIFT
COMPUTERIZED SIMULATION
CRYSTAL DEFECTS
HEAT TREATMENTS
HEXAGONAL LATTICES
MONOCLINIC LATTICES
MONTE CARLO METHOD
NMR SPECTRA
NUCLEAR MAGNETIC RESONANCE
PHASE TRANSFORMATIONS
SPECTROSCOPY
TEMPERATURE RANGE 1000-4000 K
ZEOLITES