A recently proposed approach for performing electronic-structure calculations on crystalline insulators in terms of localized orthogonal orbitals is applied to the oxides of lithium and sodium, Li2O and Na2O. Cohesive energies, lattice constants and bulk moduli of the aforementioned systems are determined at the Hartree-Fock level, and the corresponding values are shown to be in excellent agree...

Z. Naturforsch. 2009, 64b, 487 – 490; received February 20, 2009 The title compound has been synthesized under 4 GPa and at 500 ◦C from Na2O and MnO as starting materials. Rietveld refinement of the X-ray powder pattern indicates that Na6MnO4 is isostructural to Na6ZnO4 and thus is representing the second manifestation of an “isolated” [MnO4]6− anion after Na14Mn2O9. The compound crystallizes i...

Transparent bubble free phosphate glasses with composition 50P2O5-10Al2O3-20CaO-(20-x)Na2O-xCeO2 (x varying from 0 to 4 mol %) have been prepared using melt quenching technique. The amorphous nature of the prepared glass samples has been confirmed from XRD spectra. The optical absorption coefficient has been determined from the UVvisible absorption spectra. The prepared glass samples have been ...

The effect of alkali content (% K2O + %Na2O) on the mechanical properties of alkali activated blast furnace paste has been investigated. The paper presents the study on workability, compressive strength, split tensile strength and microstructure of alkali activated blast furnace slag paste specimens prepared by using of sodium silicate and potassium hydroxide solution as activators. The experim...

A thermochemical representation of the Na-Al-Si-B-O system relevant for nuclear waste glass has been developed based on the associate species approach for the glass solution phase. Thermochemical data were assessed and associate species data determined for binary and ternary subsystems in the Na2O-Al2O3-B2O3-SiO2 system. Computed binary and ternary phase diagrams were compared to published diag...

Matlab scripts that apply the Bence & Albee (1968) matrix correction algorithm to X-ray intensity data collected as element maps on a Cameca SX-50 microprobe are used to produce two-dimensional maps of oxide weight percent and cation proportions for SiO2, Al2O3, FeO, MnO, MgO, CaO, Na2O and K2O. Once generated, large data sets of mapped oxide weight percent values or cation numbers that retain ...

This paper describes an experimental test of the uni®ed theory of thermal shock. A borosilicate glass (78.1%SiO2± 13.3%B2O3±4.7%Na2O±3.4%Al2O3) subjected to ion-exchange in molten KNO3, was used. The theory predicts the critical temperature di€erence for fracture initiation by thermal shock; however, it overestimates the number of cracks which propagate simultaneously. Despite that fact, taken ...

The accumulated knowledge about the structure of a substance makes it possible to control its properties, including purposeful selection raw materials and for creation, vice versa, based on natural or artificial material composition, predict physical chemical properties. This approach allows choosing replacement rare even scarce types mineral produce particular product. analysis literature data...