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Caracterización de la solución sólida Na2(C03,S04) A 550°C

López Andrés, Sol and Marcos Pascual, Celia and Cocaño Blanco, Susana and García Martínez, O. and Prieto Rubio, Manuel (1996) Caracterización de la solución sólida Na2(C03,S04) A 550°C. In Cristalografía de Macromoléculas, Transformaciones de fase en Materiales y Crecimiento Cristalino. Univ. Oviedo, Vicerrectorado de Extensión Universitaria, Oviedo, pp. 405-415. ISBN 8460552705

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Abstract

Although it is known that unlimited solid solution exists for the high
temperature polymorphs Na2S04 (1)and α-Na2C03 , the phase relationships and the
variation of crystallographic parameters for different compositions are not studied.
Na2S04 has four well established modifications, but only the high temperature
modification Na2S04 (1) (Pб3/mmc), stable above 237°C, forms extended solid
solution series with Na2C03. At the other extreme, Na2C03 shows three polymorphs
and a rather complicated transition behaviour, being the hexagonal phase α-Na2C03
(Pб3/mmc)stable at T > 489°C.
In this paper, the crystallographic parameters were determined at 550°C for
different solid solution compositions. The study was carried out by X ray diffraction in
a high temperature powder camera. The diffraction patterns show a continuous
evolution through the entire compositional range. Crystalline spacings and cell
parameters decrease as the sulphate content decreases. This fact and the unusual
unlimited S04=-C03= substitution can be explained by the orientational disorder of
tetrahedral and triangular groups. Theoretical powder diffraction diagrams, calculated
assuming this orientational and substitutional disorder, show a good fit with the
experimentalresults.


Item Type:Book Section
Uncontrolled Keywords:Difracción de rayos X; Sufatos sódico; Carbonato sódico
Subjects:Sciences > Geology > Crystallography
ID Code:15307
Deposited On:23 May 2012 09:45
Last Modified:23 May 2012 09:45

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