منابع مشابه
Challenge to Find Quasicrystals with Seven-Fold Symmetry
Recently, Dan Shechtman was awarded the Nobel-Prize for his 1984 discovery of a quasicrystalline phase with five-fold symmetry [1] in a sputtered Al-Mn alloy. While the solid-state community considered this discovery initially with great skepticism [2], as is now vividly described in many newspaper articles and in Shechtman’s Wikipedia page [3], the existence of material with such a symmetry ha...
متن کاملSyntheses and Structures of Three Mononuclear Coordination Compounds Containing Six- and Seven-Coordinated Manganese(II) Ions
The reactions o f M n(CF3COO)2 (1) with N,N,N',N'-tetramethylethylenediamine (tmen), 2,2'-bipyridine (bipy) and triethanolamine (tea) yield three new mononuclear coordination compounds: rra«5-[Mn(tmen)2(CF3COO)2] (2), cw-[Mn(bipy)2(C F3COO)2] (3), and [Mn(tea)2](CF3COO)2 (4). The X-ray structures o f the compounds 2, 3, and 4 are described. The seven-coordination o f the manganese(II) ion in 4,...
متن کاملPrediction of 10-fold coordinated TiO2 and SiO2 structures at multimegabar pressures.
We predict by first-principles methods a phase transition in TiO2 at 6.5 Mbar from the Fe2P-type polymorph to a ten-coordinated structure with space group I4/mmm. This is the first report, to our knowledge, of the pressure-induced phase transition to the I4/mmm structure among all dioxide compounds. The I4/mmm structure was found to be up to 3.3% denser across all pressures investigated. Signif...
متن کاملPrediction of ten-fold coordinated TiO2 and SiO2 structures at multimegabar pressures
We predict by first-principles methods a phase transition in TiO2 at 6.5 Mbar from the Fe2P-type polymorph to a ten-coordinated structure with space group I4/mmm. This is the first report of the pressure-induced phase transition to the I4/mmm structure amongst all dioxide compounds. The I4/mmm structure was found to be up to 3.3% denser across all pressures investigated. Significant differences...
متن کاملOn Three-Fold Coordinated Si Sites in Mesoporous MCM-41 Catalysts
Si-NMR, gas adsorption and SAXS results are discussed to determine if the geometry and the electronic properties of Si sites, present in the MCM-41walls, are more similar to threethan to four-fold coordinated sites. The features of Si-MCM-41, SBA-15, Y zeolite and silica (SiO2), characterized by several techniques, are compared. It is shown that the pre-polymer geometries are similar to those o...
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ژورنال
عنوان ژورنال: THE REVIEW OF HIGH PRESSURE SCIENCE AND TECHNOLOGY
سال: 1998
ISSN: 0917-639X,1348-1940
DOI: 10.4131/jshpreview.7.260