Gerüststrukturen aus der Schmelze
Zusammenfassung der Projektergebnisse
Framework materials are an important field in solid state chemistry, due to their important applications in different areas like ion exchange, catalysis or gas storage. The most prevalent compounds have oxo-tetrahedral framework structures. Well known examples in that field are zeolites and aluminophosphates. Lately, compounds which incorporate more uncommon TO4 units, e.g. BO4 or BeO4 tetrahedra, were described. In most cases such compounds were synthesised by hydrothermal methods. The aim of the proposed project was to establish the synthesis of new boroarsenate framework compounds from reactive melts, both via new high-throughput and sequential syntheses. During the project 24 different boroarsenate compounds were synthesised and characterised. Six of them showed unprecedented structure types: Na2Ca3[B2As6O20(OH)4], Sr[B2As2O9(OH)2], NH4[BAsO4F], NH4[BAsO4(OH)], (NH4)2[BAs2O7(OH)], K4[BAs8O22(OH)2]Cl. Owing to the performed studies, examples for all structure types known from silicate chemistry, representing different degrees of framework dimensionality, i.e. oligomers, chains, bands, layers and frameworks, are now optained. Furthermore the first example of a boroarsenate occuring in two polomorphic structures (NH4)2[BAs2O7(OH)] was found. In the structure of K4[BAs8O22(OH)2]Cl, for the first time, AsO6-octahedra as a new building block in boroarsenates were observed. Additionally, the SXD-PND method was tested on seven beryllosilicate mineral samples and detailed structural investigations regarding the hydrogen atom positions were performed. Using this analytical tool it is possible to characterise also hydrogen containing boroarsenates. Therefore it will be possible to resolve open questions regarding the position of H-atoms and hydrogen bonding in compounds such as (NH4)2[BAs2O7(OH)] and K4[BAs8O22(OH)2]Cl.
Projektbezogene Publikationen (Auswahl)
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Determination of hydrogen positions in framework beryllate minerals and materials by combined X-ray and neutron diffraction. XXI. Congress of the International Union of Crystallography 2008, Osaka, Japan
A. Lieb, J. A. Armstrong, A. A. Finch, H. Friis, M. T. Weller
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Die Alkalimetall-Boroarsenate Sr2[B2As2O9(OH)2] und Ba[B2As2O8(OH)2]. Hemdsärmel-Kolloquium 2008, Mainz
A. Lieb
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Inorganic framework compounds with unusual building units. RSC Solid State Group Christmas Meeting 2008, Southampton, Großbritannien
A. Lieb
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NH4[BAsO4F] - a new layer boroarsenate with a silicate topology. 14. Fachgruppentagung der GDCh: Festkörperchemie und Materialforschung 2008, Bayreuth
A. Lieb, M. T. Weller
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Determination of the hydrogen positions in the new barium boroarsenate Ba[B2As2O8(OH)2] by combined single crystal X-ray / powder neutron and solid state NMR investigations. 12th European Conference on Solid State Chemistry ECSSC 2009, Münster
A. Lieb, D. Hirsemann, J. Senker, M. T. Weller
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M[BAsO4(F,OH)] with M = NH4, Rb ,Cs - An Open- Framework Fluoro-Boroarsenate with a Zeolite-Like Structure Related to the Gismondine Topology. 21. Deutsche Zeolith-Tagung 2009, Kiel
A. Lieb, M. T. Weller
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NH4[BAsO4F] - a new layer fluoro-boroarsenate with a silicate related topology. Z. Anorg. Allg. Chem. 2009, 635, 1877.
A. Lieb, M. T. Weller
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Determination of hydrogen positions by combined single crystal X-ray / powder neutron diffraction. SNI 2010 - Deutsche Tagung für Forschung mit Synchrotronstrahlung, Neutronen und Ionenstrahlen an Großgeräten, FU Berlin (24.-26.2.2010)
A. Lieb, V.P. Ting, P.F. Henry and M.T. Weller
