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Reinvestigation of pure Na-nepheline like compounds obtained from the thermal conversion of zeolite LTA

Predrag Vulic, Volker Kahlenberg, Christian Gspan and Radovan Dimitrijevic
Reinvestigation of pure Na-nepheline like compounds obtained from the thermal conversion of zeolite LTA
European Journal of Mineralogy (September 2013) 25 (3): 473-478

Abstract

A polycrystalline sample synthesized through the thermal transformation of zeolite Na-LTA and originally described as standard nepheline was re-investigated. Transmission electron microscopy (TEM) proved the presence of a structure with a tripled c unit-cell parameter compared to that observed in classical nepheline. Consequently, the theoretical X-ray powder diagrams of all known trinepheline compounds were compared with the experimental powder pattern, leading to the conclusion that the material is actually a mixture of two phases. Rietveld refinement against XRPD data using structural models of (a) classical Na-nepheline (S. G. P6 (sub 3) , a = 9.971(3), c = 8.349(2) Aa) and (b) monoclinic trinepheline (space group P112 (sub 1) , a = 9.995(4), b = 9.963(4), c = 24.988(7) Aa, gamma = 119.75(3) degrees ) resulted in a satisfying agreement between calculated and observed step intensities (chi (super 2) = 1.96, R (sub wp) = 11.3, R (sub p) = 8.77). The additional quantitative analyses of the samples obtained in a temperature range of stability of nepheline (900-1100 degrees C) showed the presence of both structures, and also a gradual increase of the weight fraction of the monoclinic trinepheline phase with increasing temperature.


ISSN: 0935-1221
EISSN: 1617-4011
Serial Title: European Journal of Mineralogy
Serial Volume: 25
Serial Issue: 3
Title: Reinvestigation of pure Na-nepheline like compounds obtained from the thermal conversion of zeolite LTA
Affiliation: University of Innsbruck, Institute of Mineralogy and Petrography, Innsbruck, Austria
Pages: 473-478
Published: 201309
Text Language: English
Publisher: Schweizerbart'sche Verlagsbuchhandlung (Naegele u. Obermiller), Stuttgart, Germany
References: 22
Accession Number: 2013-083996
Categories: Mineralogy of silicates
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 2 tables
Secondary Affiliation: University of Belgrade, SRB, SerbiaGraz University of Technology, AUT, Austria
Country of Publication: Germany
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Abstract, copyright, Schweizerbart'sche Verlagsbuchhandlung. Reference includes data from GeoScienceWorld, Alexandria, VA, United States
Update Code: 201349
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