نتایج جستجو برای: Sodalite
تعداد نتایج: 304 فیلتر نتایج به سال:
Temperature-dependent EPR data of potassium-electro-sodalite (PES), K8[Al6Si6O24](e-)2, are consistent with the occurrence of an antiferromagnetic phase transition at 71±2 K. PES is a Mott insulator which contains an unpaired electron in every sodalite cage. The same transition in sodium-electro-sodalite occurs at a considerably lower temperature (42 K), indicating that the exchange interaction...
A B S T R A C T: The K~mpf & Schwertmann (1982) procedure for concentrating iron oxides in soil clays by dissolution of kaolin and gibbsite by boiling for 1 h in 5 M NaOH may not dissolve all kaolin, and also results in the precipitation of sodalite. For the complete dissolution of kaolin in kaolin-rich soil clays a boiling time of 2 h in 5 M NaOH was required. The large amounts of sodalite pro...
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 • 2H20 could be synthesized in form of polycrystalline powder as well as in form of single crystals. The kinetics of the sodalite growth could...
Cancrinite, sodalite, and zeolite A have been found to form upon contacting hyperalkaline simulated tank waste (STW) with vadose zone sediments from the Hanford Reservation. Here, soluble silica and STW are used to study mineral formation and transformation. Two Hanford sediment fractions (diameters <50 and >50 lm instead of soluble silica) are also used as silica sources for comparison. A seri...
Optical properties of silver Ag(n) nanoclusters are demonstrated to be dependent on their size, structure and charge state. It is found that when being contained in the sodalite cavity of LTA zeolite the tetradecanuclear hexacation silver cluster Ag14(6+) is stable. Its lower-lying states and optical spectrum are theoretically determined using the quantum chemical TD-DFT method. Its ground stat...
in this study, a sodalite nanozeolite was synthesized and characterized by x-ray diffraction (xrd) and scanning electronic microscopy (sem). following the morphology evolution of the sodalite nanozeolite in the sem images illustrates the formation of the spherical particle with a size between 60 and 80 nm. then, carbon paste electrode (cpe) was modified by sodalite nanozeolite and ni2+ ions. th...
(ABSTRACT) Several novel silica structures have been generated using a simulated-annealing strategy with an ab-initio based covalent-bonding potential. First-principles total-energy pseu-dopotential methods have been used to examine several promising novel structures and to compare their structural parameters, cohesive energies and bulk moduli with those of low-quartz, low-cristobalite, silica-...
perlite or pearl stone is a natural glass which has formed by rapid cooling of viscous lava or magma. perlite is mainly composed of silica, aluminum, potassium and sodium. in this experiment, perlite was used as a low-cost source of si and al to synthesis of sodalite zeolite using the alkaline hydrothermal treatment. a statistical taguchi design of experiments was employed to evaluate the effec...
Franzinite, ideally [(Na,K)30Ca10][Si30Al30O120](SO4)10•2H2O, a feldspathoid belonging to the cancrinite group, has a tenlayer stacking sequence. Its structure was solved in the space group P321 to an R value of 5.96%. Cell parameters are a 12.916(1), c 26.543(3) Å. The framework, characterized by the stacking sequence ABCABACABC, contains regular alternations of two “cancrinite” and two “sodal...
Introduction: The search for the former existence in the Early Solar System of the now extinct radionuclide Cl (T1⁄2 = 3x10 a) has proven to be difficult [e.g., 1]. This is at least partly due to the volatility of chlorine and the fact that in primitive meteorites Cl occurs in high abundance only in alteration phases such as sodalite (Na8Al6Si6O24Cl2). 36-Cl decays to both Ar by β decay (98.1 %...
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