A genetic algorithm has been used to generate crystal framework structures, including that of sodalite and chabazite, from the knowledge of only the unit cell dimensions, constituent elements and by defining exclusion zones–regions within the unit cell where the constituent elements are forbidden, as opposed to being discouraged. We present details of a direct approach to restricting the possib...

We have investigated various silica zeolites using density functional theory with periodic supercells, plane waves, and pseudopotentials. These zeolitic phases include silica sodalite, chabazite, mordenite, silica LTA, and silicalite. Atom-level geometries, elastic properties, and cohesive energies are presented. Although the zeolites exhibit a wide range of Si-O-Si angles and densities, the co...

The article presents the results of first study stage aimed at analyzing luminescent properties main and minor minerals composing apatite–nepheline ores host rocks in deposits Khibiny rock massif (Kola Peninsula, Russia). purpose work was a search stable identification feature providing fast safe determination fluorapatite mineral mixture solving technological tasks, namely sampling borehole wa...

Hydrogen-rich compounds hold promise as high-temperature superconductors under high pressures. Recent theoretical hydride structures on achieving high-pressure superconductivity are composed mainly of H(2) fragments. Through a systematic investigation of Ca hydrides with different hydrogen contents using particle-swam optimization structural search, we show that in the stoichiometry CaH(6) a bo...

12 13 The removal of fluoride using red mud has been improved by acidifying red mud with 14 hydrochloric, nitric and sulphuric acid. This investigation shows that the removal of fluoride 15 using red mud is significantly improved if red mud is initially acidified. The acidification of 16 red mud causes sodalite and cancrinite phases to dissociate, confirmed by the release of 17 sodium and alumi...

Article history: Received 19 August 2014 Accepted 15 September 2014 The radioisotope I, a fission product in spent nuclear fuel, has a long half-life, and can be highly mobile in the environment. Iodine K-edge X-ray absorption spectra were collected to characterize the iodine valence and coordination environment in simulated Hanford low activity waste glasses. Both iodine XANES and EXAFS data f...

The hydrothermal crystallizations of two zeolite topologies (FAU and LTA) have been studied by simultaneous UV-Raman spectroscopy and X-ray diffraction in a home built setup. A wide angle X-ray diffractometer has been redesigned and combined with Raman components. The results revealed, despite similar structures of the starting gels, different aluminosilicate species evolved in the two systems,...