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Titolo:
The structures of the Ce and LaN-phases RE3Si8-xAlxN11-xO4+x (x approximate to 1.75 for RE = Ce, x approximate to 1.5 for RE = La), determined by single-crystal X-ray and time-of-flight neutron powder diffraction, respectively
Autore:
Grins, J; Shen, ZJ; Esmaeilzadeh, S; Berastegui, P;
Indirizzi:
Stockholm Univ, Arrhenius Lab, Dept Inorgan Chem, SE-10691 Stockholm, Sweden Stockholm Univ Stockholm Sweden SE-10691 hem, SE-10691 Stockholm, Sweden
Titolo Testata:
JOURNAL OF MATERIALS CHEMISTRY
fascicolo: 9, volume: 11, anno: 2001,
pagine: 2358 - 2362
SICI:
0959-9428(2001)11:9<2358:TSOTCA>2.0.ZU;2-H
Fonte:
ISI
Lingua:
ENG
Soggetto:
NITROGEN; SILICATES; CERAMICS; SYSTEM;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Engineering, Computing & Technology
Citazioni:
25
Recensione:
Indirizzi per estratti:
Indirizzo: Grins, J Stockholm Univ, Arrhenius Lab, Dept Inorgan Chem, SE-10691 Stockholm, Sweden Stockholm Univ Stockholm Sweden SE-10691 0691 Stockholm, Sweden
Citazione:
J. Grins et al., "The structures of the Ce and LaN-phases RE3Si8-xAlxN11-xO4+x (x approximate to 1.75 for RE = Ce, x approximate to 1.5 for RE = La), determined by single-crystal X-ray and time-of-flight neutron powder diffraction, respectively", J MAT CHEM, 11(9), 2001, pp. 2358-2362

Abstract

Single crystals of the sialon Ce N-phase Ce3Si8-xAlxN11-xO4+x (x approximate to 1.75) were obtained via a novel route, i.e. by first preparing a fully compacted body with phase constitutions far away from thermal dynamic equilibrium by means of a fast densification technique, spark plasma sintering, and then heat treating this compact in a sialon powder bed at 1600 degreesC in N-2 atmosphere for 24 h. The structure of the Ce N-phase was solved using MoK alpha single-crystal data and direct methods. It was refined in space group I2/a with a = 15.798(1). b = 4.8939(3), c = 17.990(1) Angstrom, beta = 114.816(4)degrees, V = 1262.4 Angstrom (3), to a weighted R(F-obs(2))= 6.7% for 977 unique reflections. The isostructural La phase structure was refined with anisotropic thermal parameters for La and N/O atoms using time-of flight neutron powder diffraction data. The structure exhibits three structural kinds of N/O anions: 4/15 of these are N atoms which are triangularly coordinated by 3 Si/Al atoms, 2/15 are tetrahedron free apex O atoms which are in addition bonded to 3 Ce/La atoms while the remaining 9/15 are on sites that are statistically occupied by N and O atoms and which are bonded to 2 tetrahedral Si/Al atoms and 1-2 Ce/La atoms. Comparisons are made with a previous structural proposal deduced from solid state nuclear magnetic resonance spectra.

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Documento generato il 24/11/17 alle ore 17:27:38