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Relationship between IR spectra and crystal structures of beta -tridymite-like CsM (super 2+) PO (sub 4) compounds

Elena Yu. Borovikova, Victoria Kurazhkovskaya, Dmitriy Ksenofontov, Yuriy Kabalov, Vladimir Pet'kov and Elena Asabina
Relationship between IR spectra and crystal structures of beta -tridymite-like CsM (super 2+) PO (sub 4) compounds (in The 7th European conference on Mineralogy and spectroscopy, Monika Koch-mueller (editor), Michael Fechtelkord (editor), Vladimir Khomenko (editor) and Sergio Speziale (editor))
European Journal of Mineralogy (September 2012) 24 (5): 777-782


Caesium-bearing phosphates with the beta -tridymite structure are considered as storage container for radioactive Cs. In this context, double phosphates of caesium and divalent cations, CsM (super 2+) PO (sub 4) where M (super 2+) =Zn, Co, Mn, Mg, and Ni, have been synthesised by the precipitation method as powders and investigated by infrared spectroscopy in combination with factor-group analyses for band assignment. Comparison of the IR pattern of CsZnPO (sub 4) and CsCoPO (sub 4) confirms that they are isomorphic (space group P1 2 (sub 1) /a 1 at room conditions). Both undergo T-induced phase transitions: one at 260 degrees C (Pn2 (sub 1) a) and another one at 310 degrees C (Pnma). High-temperature IR spectra of the orthorhombic modifications of CsZnPO (sub 4) are presented and assigned. Comparison of the IR-spectrum of CsMnPO (sub 4) with that of CsZnPO (sub 4) (Pn2 (sub 1) a) confirms that it crystallizes in the orthorhombic structure at room conditions (Pn2 (sub 1) a). CsMgPO (sub 4) crystallizes at room conditions in the orthorhombic space group Pnma, however, it tends to hydrate immediately after quenching in air forming the cubic hydrate CsMgPO (sub 4) .6H (sub 2) O (space group F43m). The liability to hydration is also characteristic for CsNiPO (sub 4) . Temperature-dependent IR spectroscopy, X-ray diffraction, thermal analyses (TGA, DTA) and second-harmonic generation (SHG) revealed that pure anhydrous CsMgPO (sub 4) (space group Pnma) can only be stored in air at temperatures higher than 150 degrees C. Our study proves that CsM (super 2+) PO (sub 4) , where M (super 2+) =Zn, Co, Mn, may be stable containers for radioactive Cs at room temperatures. However, CsMgPO (sub 4) and CsNiPO (sub 4) can only be used as crystalline matrices for the immobilisation of radioactive Cs when stored at temperature higher than 150 degrees C due to their hydrolytic instability in air. The difference in the structures of CsMg phosphate and Cs phosphates with Zn, Co, and Mn is caused by the different liability of these cations to form either ionic or covalent chemical bonds.

ISSN: 0935-1221
EISSN: 1617-4011
Serial Title: European Journal of Mineralogy
Serial Volume: 24
Serial Issue: 5
Title: Relationship between IR spectra and crystal structures of beta -tridymite-like CsM (super 2+) PO (sub 4) compounds
Title: The 7th European conference on Mineralogy and spectroscopy
Author(s): Borovikova, Elena Yu.Kurazhkovskaya, VictoriaKsenofontov, DmitriyKabalov, YuriyPet'kov, VladimirAsabina, Elena
Author(s): Koch-mueller, Monikaeditor
Author(s): Fechtelkord, Michaeleditor
Author(s): Khomenko, Vladimireditor
Author(s): Speziale, Sergioeditor
Affiliation: Moscow State University, Department of Crystallography and Crystal Chemistry, Moscow, Russian Federation
Affiliation: Deutsches GeoForschungsZentrum, Helmholtz-Zentrum Potsdam, Potsdam, Germany
Pages: 777-782
Published: 201209
Text Language: English
Publisher: Schweizerbart'sche Verlagsbuchhandlung (Naegele u. Obermiller), Stuttgart, Germany
Meeting name: The 7th European conference on Mineralogy and spectroscopy
Meeting location: Potsdam, DEU, Germany
Meeting date: 20110904Sept. 4-7, 2011
References: 24
Accession Number: 2012-086340
Categories: Mineralogy of non-silicates
Document Type: Serial Conference document
Bibliographic Level: Analytic
Illustration Description: illus. incl. 1 table
Secondary Affiliation: Ruhr-Universitaet Bochum, DEU, GermanyNizhni Novgorod State University, RUS, Russian Federation
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: 201245
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