High-temperature synthesis, single-crystal X-ray and neutron powder diffraction, and materials properties of Sr(3)Ln(10)Si(18)Al(12)O(18)N(36) (Ln = Ce, Pr, Nd)-novel sialons with an ordered distribution of Si, Al, O, and N


Lauterbach, R., Irran, E., Henry, P. F., Weller, M. T. and Schnick, W. (2000) High-temperature synthesis, single-crystal X-ray and neutron powder diffraction, and materials properties of Sr(3)Ln(10)Si(18)Al(12)O(18)N(36) (Ln = Ce, Pr, Nd)-novel sialons with an ordered distribution of Si, Al, O, and N. Journal of Materials Chemistry, 10, (6), 1357-1364. (doi: 10.1039/a908844j).

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Description/Abstract

The novel oxonitridoaluminosilicates (sialons) Sr(3)Ln(10)Si(18)Al(12)O(18)N(36) (Ln = Ce, Pr, Nd) were obtained by the reaction of the respective lanthanide metals with Si(NH)(2), SrCO3, and AlN using a radiofrequency furnace at temperatures between 1550-1650 degrees C. The crystal structures of the isotypic sialons were determined by single-crystal X-ray investigations (Sr3Ce10Si18Al12O18N36: I (4) over bar 3m, Z = 2, a = 1338.2(2) pm, R1 = 0.0333; Sr3Pr10Si18Al12O18N36: a = 1334.54(6) pm, R1 = 0.0296; Sr3Nd10Si18Al12O18N36: a = 1332.85(6) pm, R1 = 0.0271) and in the case of Sr3Pr10Si18Al12O18N36 with powder neutron diffraction as well. The three-dimensional sialon network is built up by SiON3, SiN4, and AlON3 tetrahedra. Besides the bridging O and N atoms of the sialon network there are isolated O2- which are tetrahedrally coordinated by Sr and Ln. The crystallographic differentiation of Si/Al and O/N seemed to be possible by a careful evaluation of the single-crystal X-ray diffraction data combined with lattice energy calculations using the MAPLE concept (Madelung Part of Lattice Energy). In the case of Sr3Pr10Si18Al12O18N36 the differentiation of O and N and the proposed ordering was completely confirmed by powder neutron diffraction.

Item Type: Article
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Keywords: yttrium alpha-sialon, mechanical-properties, containing melilites, ceramics, nitrogen, sm, nd2si2.5al0.5o3.5n3.5, extension, y2si3o3n4, silicate
Subjects: Q Science
Q Science > QD Chemistry
Divisions: University Structure - Pre August 2011 > School of Chemistry
ePrint ID: 19010
Date Deposited: 18 Jan 2006
Last Modified: 27 Mar 2014 18:08
URI: http://eprints.soton.ac.uk/id/eprint/19010

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