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Titolo:
The crystal structure of a mixed alkali phyllosilicate with composition Na1.55K0.45Si2O5
Autore:
Rakic, S; Kahlenberg, V;
Indirizzi:
Univ Bremen, Fachbereich Geowissensch Kristallog, D-28359 Bremen, Germany Univ Bremen Bremen Germany D-28359 h Kristallog, D-28359 Bremen, Germany
Titolo Testata:
EUROPEAN JOURNAL OF MINERALOGY
fascicolo: 6, volume: 13, anno: 2001,
pagine: 1215 - 1221
SICI:
0935-1221(200111/12)13:6<1215:TCSOAM>2.0.ZU;2-7
Fonte:
ISI
Lingua:
ENG
Soggetto:
DISILICATE GLASSES; SILICATES; HYGROSCOPICITY; SYSTEMS;
Keywords:
single-layer silicate; Na1.55K0.45Si2O5; single-crystal structure analysis; phyllosilicate;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
29
Recensione:
Indirizzi per estratti:
Indirizzo: Rakic, S Univ Bremen, Fachbereich Geowissensch Kristallog, Klagenfurter Str, D-28359 Bremen, Germany Univ Bremen Klagenfurter Str Bremen Germany D-28359 men, Germany
Citazione:
S. Rakic e V. Kahlenberg, "The crystal structure of a mixed alkali phyllosilicate with composition Na1.55K0.45Si2O5", EUR J MINER, 13(6), 2001, pp. 1215-1221

Abstract

The crystal structure of Na-1.55 K0.45Si2O5 has been solved and refined toa final residual R1 of 0.048 for 1208 independent reflections. The compound is monoclinic with space group P2(1)/c (a = 4.845(1) Angstrom, b = 8.647(2) Angstrom, c = 11.992(3) Angstrom, beta = 90.31(4)degrees, V= 503.1(4) Angstrom (3), M-r = 189.40 u, Z = 4, lambda (MoKalpha) = 0.71073 Angstrom, D-x = 2.51 g/cm(3), mu (MoKalpha) = 1.14 mm(-1)), The crystal showed twinningby pseudo-merohedry according to 2([100]), a feature which was accounted for in the refinements. The compound belongs to the group of single-layer silicates. Individual sheets can be described as being built by the condensation of Zweier single chains of SiO4 tetrahedra parallel to the a axis or, alternatively, by condensation of Vierer single chains parallel to the b axis. The layers contain six-membered rings in UUDUUD or DDUDDU conformation. The stacking of the layers parallel to the c axis results in a three-dimensional structure in which the alkali cations reside between the layers for charge compensation. The distribution of the alkali atoms among the two crystallographically different M(l) and M(2) positions shows a definite preference by the larger potassium for the M(l) site. The smaller M(2) site is K-free.

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Documento generato il 18/11/17 alle ore 03:36:26