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| Naji, M. |
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| Motta, Antonella |
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| Aletan, Dirar |
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| Mohamed, Tarek |
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| Ertürk, Emre |
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| Taccardi, Nicola |
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| Kononenko, Denys |
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| Petrov, R. H. | Madrid |
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| Alshaaer, Mazen | Brussels |
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| Bih, L. |
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| Casati, R. |
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| Muller, Hermance |
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| Kočí, Jan | Prague |
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| Šuljagić, Marija |
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| Kalteremidou, Kalliopi-Artemi | Brussels |
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| Azam, Siraj |
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| Ospanova, Alyiya |
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| Blanpain, Bart |
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| Ali, M. A. |
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| Popa, V. |
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| Rančić, M. |
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| Ollier, Nadège |
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| Azevedo, Nuno Monteiro |
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| Landes, Michael |
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| Rignanese, Gian-Marco |
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Lengauer, Christian
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Publications (2/2 displayed)
- 2009Investigations in the systems Sr-As-O-X (X = H, Cl): Preparation and crystal structure refinements of the anhydrous arsenates(V) Sr3(AsO4)2, Sr2As2O7, a- and ß-SrAs2O6, and of the apatite-type phases Sr5(AsO4)3OH and Sr5(AsO4)3Cl
- 2009Partial ordering in the section Hf5Ge4-Zr5Ge4: Crystallographic investigation and modeling based on ab initio calculationscitations
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article
Investigations in the systems Sr-As-O-X (X = H, Cl): Preparation and crystal structure refinements of the anhydrous arsenates(V) Sr3(AsO4)2, Sr2As2O7, a- and ß-SrAs2O6, and of the apatite-type phases Sr5(AsO4)3OH and Sr5(AsO4)3Cl
Abstract
The previously uninvestigated atomic arrangements of six strontium arsenate(V) phases in the systems Sr-As-O-X (X = H, Cl) have been determined. Single crystals of Sr3(AsO4)2 and Sr5(AsO4)3Cl were grown from a borate and NaCl melt, respectively, whereas single crystals of a- and ß-SrAs2O6 and of Sr5-(AsO4)3OH were obtained under hydrothermal conditions. Microcrystalline samples of Sr2As2O7 were prepared by solid-state reaction of As2O5 with SrCO3 and, alternatively, by thermolysis of SrHAsO4. Crystal structure determinations based on powder X-ray diffraction data using the Rietveld method (Sr2As2O7), and from single-crystal X-ray diffraction data (all other phases) revealed isotypism with known structure types (except ß-SrAs2O6 which represents a new structure type). Sr3(AsO4)2 crystallizes in the K2Pb(SO4)2 structure type; Sr2As2O7 is isotypic with the high-temperature polymorphs of Ca2P2O7 and Sr2V2O7, but itself shows no polymorphism; Sr5(AsO4)3OH and Sr5(AsO4)3Cl crystallize with the hydroxylapatite and chloroapatite structure, respectively; SrAs2O6 is dimorphic. Like all other known MIIAs2O6 metaarsenates (M = Mn, Co, Ni, Sr, Pd, Cd, Hg, Pb), the a-polymorph crystallizes in the PbSb2O6 structure type, whereas the novel ß-polymorph is the first example of a MIIAs2O6 superstructure with a doubled c-axis. Additional analytical methods using Raman spectroscopy and thermal analyses support the results of the X-ray structure work.