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Titolo: Computational study of tetrahedral AlSi ordering in muscovite
Autore: Palin, EJ; Dove, MT; Redfern, SAT; Bosenick, A; SainzDiaz, CI; Warren, MC;
 Indirizzi:
 Univ Cambridge, Dept Earth Sci, Cambridge CB2 3EQ, England Univ CambridgeCambridge England CB2 3EQ Sci, Cambridge CB2 3EQ, England CSIC, Estac Expt Zaidin, E18008 Granada, Spain CSIC Granada Spain E18008 IC, Estac Expt Zaidin, E18008 Granada, Spain
 Titolo Testata:
 PHYSICS AND CHEMISTRY OF MINERALS
fascicolo: 8,
volume: 28,
anno: 2001,
pagine: 534  544
 SICI:
 03421791(200109)28:8<534:CSOTAO>2.0.ZU;2H
 Fonte:
 ISI
 Lingua:
 ENG
 Soggetto:
 MASNMR SPECTROSCOPY; COMPUTERSIMULATION; LAYER SILICATES; FRAMEWORK STRUCTURES; THERMODYNAMICS; TRANSITION; ENERGY; SHEET; MICAS;
 Keywords:
 muscovite; AlSi ordering; layer silicates; phase transitions; Monte Carlo simulations;
 Tipo documento:
 Article
 Natura:
 Periodico
 Settore Disciplinare:
 Physical, Chemical & Earth Sciences
 Citazioni:
 24
 Recensione:
 Indirizzi per estratti:
 Indirizzo: Dove, MT Univ Cambridge, Dept Earth Sci, Downing St, Cambridge CB2 3EQ, England Univ Cambridge Downing St Cambridge England CB2 3EQ 3EQ, England



 Citazione:
 E.J. Palin et al., "Computational study of tetrahedral AlSi ordering in muscovite", PHYS CHEM M, 28(8), 2001, pp. 534544
Abstract
The nature of AlSi ordering across the tetrahedral sites in muscovite, K2Al4(Si6Al2O20)(OH)(4), was investigated using various computational techniques. Values of the atomic exchange interaction parameters J(l) were obtained. From these parameters, a twodimensional AlSi ordering scheme was deduced. The transition temperature Tc for this twodimensional ordering is 1900 K. There are several possible ordering schemes in three dimensions. basedon different stacking sequences of ordered sheets of tetrahedral sites. Monte Carlo simulations of both twodimensional and threedimensional ordering were performed. but in the threedimensional simulation only the twodimensional ordering is seen, implying that threedimensional ordering is too slow to be attained during the timescale of the simulation. The effect of the threedimensional interactions is to raise the twodimensional ordering temperature to 2140 K. From the threedimensional Monte Carlo simulation. the frequency of occurrence of 4Si0Al. 3Si1Al, 2Si2Al and 1Si3Al clusters wasdetermined, which match those inferred by Si29 MASNMR measurements reasonably well. In fact, the match suggests that the cation ordering seen in experiments corresponds to a configuration with considerable shortrange order but no longrange order, similar to a state that is at a temperature justabove an ordering phase transition.
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Documento generato il 18/11/17 alle ore 03:41:00