Compound La[B5O8(OH)2] with a new type of pentaborate layer based on the 5[3T + 2Δ] block: Topology-symmetry analysis and the position in the structural system
| Autor: | E. L. Belokoneva, Olga V. Dimitrova, Anna G. Ivanova, N. N. Mochenova |
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| Rok vydání: | 2006 |
| Předmět: | |
| Zdroj: | Crystallography Reports. 51:584-588 |
| ISSN: | 1562-689X 1063-7745 |
| Popis: | Crystals of a new rare-earth borate, LaB5O8(OH)2 (space group P21/n), are synthesized under hydrothermal conditions. The crystal structure is determined by the heavy-atom method without prior knowledge of the chemical formula. The radical anion is a layer composed of pentaborate blocks 5[3T + 2Δ]. The topological and symmetric patterns of their condensation differ from those observed in all known layered pentaborates containing the same block. The building blocks are shared by vertices of tetrahedra to form chains. These chains are joined into a corrugated layer in such a way that one of the BO3 triangles of the building block is terminal and the layer itself is denser than those previously revealed in all other borates. In contrast to the majority of layer borates, the new La borate does not contain water molecules, because it crystallizes from more concentrated solutions. The La atoms are located inside the walls of the hollows of corrugated layers, thus centering the holes of the layers. |
| Databáze: | OpenAIRE |
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