Publication: Caracterización de la solución sólida Na2(C03,S04) A 550°C
Loading...
Official URL
Full text at PDC
Publication Date
1996
Advisors (or tutors)
Editors
Journal Title
Journal ISSN
Volume Title
Publisher
Univ. Oviedo, Vicerrectorado de Extensión Universitaria
Citations
Exportar
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.