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Titolo:
Computational study of tetrahedral Al-Si ordering in muscovite
Autore:
Palin, EJ; Dove, MT; Redfern, SAT; Bosenick, A; Sainz-Diaz, 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, E-18008 Granada, Spain CSIC Granada Spain E-18008 IC, Estac Expt Zaidin, E-18008 Granada, Spain
Titolo Testata:
PHYSICS AND CHEMISTRY OF MINERALS
fascicolo: 8, volume: 28, anno: 2001,
pagine: 534 - 544
SICI:
0342-1791(200109)28:8<534:CSOTAO>2.0.ZU;2-H
Fonte:
ISI
Lingua:
ENG
Soggetto:
MAS-NMR SPECTROSCOPY; COMPUTER-SIMULATION; LAYER SILICATES; FRAMEWORK STRUCTURES; THERMODYNAMICS; TRANSITION; ENERGY; SHEET; MICAS;
Keywords:
muscovite; Al-Si 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 Al-Si ordering in muscovite", PHYS CHEM M, 28(8), 2001, pp. 534-544

Abstract

The nature of Al-Si 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 two-dimensional Al-Si ordering scheme was deduced. The transition temperature T-c for this two-dimensional 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 two-dimensional and three-dimensional ordering were performed. but in the three-dimensional simulation only the two-dimensional ordering is seen, implying that three-dimensional ordering is too slow to be attained during the timescale of the simulation. The effect of the three-dimensional interactions is to raise the two-dimensional ordering temperature to 2140 K. From the three-dimensional Monte Carlo simulation. the frequency of occurrence of 4Si0Al. 3Si1Al, 2Si2Al and 1Si3Al clusters wasdetermined, which match those inferred by Si-29 MAS-NMR measurements reasonably well. In fact, the match suggests that the cation ordering seen in experiments corresponds to a configuration with considerable short-range order but no long-range 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