| | 1 | Author
| Peter Rögner, Klaus-Jürgen Range | Requires cookie* | | | Title
| Strukturverfeinerung von Rubidiumperrhenat bei 297 und 159 K Structure Refinement of Rubidium Perrhenate at 297 and 159 K  | | | | Abstract
| The scheelite-type structure of rubidium per rhenate, R b R e 0 4, has been confirmed and refined from single-crystal X-ray data at two tempera tures. The com pound crystallizes tetragonally, space group I4,/a, with a = 5,8401(5), c = 13,265(2) A at 297(1) K, and a = 5,8289(7), c = 13,109(2) A at 159(3) K, respectively. Except for a significant decrease in the anisotropic displace ment factors, the changes in the structural para meters at low temperature are rather small. Im Zusam m enhang mit unseren Untersuchun gen zu tem peraturinduzierten Phasenumwandlun | | | |
Reference
| Z. Naturforsch. 48b, 233—234 (1993); eingegangen am 30. September 1992 | | | |
Published
| 1993 | | | |
Keywords
| Rubidium Perrhenate, Structure Refinement, Scheelite-Type Structure | | | |
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| default:Reihe_B/48/ZNB-1993-48b-0233_n.pdf | | | | Identifier
| ZNB-1993-48b-0233_n | | | | Volume
| 48 | |
| 2 | Author
| Danita De, W. Aal, *. Klaus-Jürgen, R. An | Requires cookie* | | | Title
| Structure Refinem ent o f Potassium Periodate at 297 and 150 K | | | | Abstract
| The scheelitetype structure of potassium perio date, K I 0 4, has been confirmed and refined from single-crystal X-ray data at two temperatures. The compound crystallizes tetragonally, space group 14,/a, with a = 5.726(1), c = 12.607(4) Ä at 297(1) K, and a = 5.704(3), c = 12.478(8) A at 150(1) K, respectively. Except for a significant decrease in the anisotropic displacement factors, the changes in the structural parameters at low temperature are rather small. | | | |
Reference
| Z. Naturforsch. 51b, 444—446 (1996); eingegangen am 4. August 1995 | | | |
Published
| 1996 | | | |
Keywords
| Potassium Periodate, Structure Refinement, Scheelite-Type Structure | | | |
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| default:Reihe_B/51/ZNB-1996-51b-0444_n.pdf | | | | Identifier
| ZNB-1996-51b-0444_n | | | | Volume
| 51 | |
| 4 | Author
| J.-Ch Buhl, C. Mundus, J. Löns, W. Hoffmann | Requires cookie* | | | Title
| On the Enclathration of N aB(O H )4 in the /J-Cages of Sodalite: Crystallization Kinetics and Crystal Structure | | | | Abstract
| The hydrothermal formation of sodium hydroxyborate enclathrated sodalite synthesized from an initial ternary mixture of mullite, cristobalite and corundum has been investigated. Depending on temperature and pressure the compound Na7-5[AlSi04]6[B(0H)4]1.5 • 2 H 20 could be synthesized in form of polycrystalline powder as well as in form of single crystals. The kinetics of the sodalite growth could be determined at 423 K and 473 K. 29Si-and 27A1 MAS NMR was shown to be the preferred method to describe the conversion into sodalite quantitatively. Evidence for the first formation of polycrystalline sodalite has been found after the total dissolution of mullite and cristobalite. Single crystal X-ray diffraction data were used for the structure determination and refinement. The position and orientation of the hydroxyborate anions within the sodalite's /J-cages could only be found in the course of a "rigid body" refinement with constraints for the B(OH)4 tetrahedron. The boron atoms are located in an off-centre position within the sodalite cages. One out of the four oxygen atoms of the hydroxyborate group is positioned near the centre of a face of the sodium tetrahedron, whereas the three remaining oxygen atoms are near to the middle of its edges. | | | |
Reference
| Z. Naturforsch. 49a, 1171—1178 (1994); received September 26 1994 | | | |
Published
| 1994 | | | |
Keywords
| Sodalite solid solution, Crystallization kinetics, IR-spectroscopy, MAS NMR, Structure refinement | | | |
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| default:Reihe_A/49/ZNA-1994-49a-1171.pdf | | | | Identifier
| ZNA-1994-49a-1171 | | | | Volume
| 49 | |
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