RESUMEN
By first-principles calculations with density functional theory and a pseudopotential approach, the structural, electronic, and optical properties of the anhydrous 4C16H10Br2O2 Bis (2-Bromobenzoyl) Methane crystals in Pbnc (N°60) and P21/c (N°14) space group are investigated. All computations are determined by a generalized gradient approximation, local density approximation and an ultra-soft pseudopotential. The calculated equilibrium parameters are in good agreement with their available experimental data. This calculation shows that the GGA/PW91 functional overestimate the lattice constant, unlike the LDA/CA-PZ. The Br-C bond distance of 1.856 (1.902) Å is comparable with experimental value of 1.901 (1.896) Å in Pbnc (P21/c) space groups. The direct band gap nature is obtained for both space groups Pbnc and P21/c, since the maximum of the valence band and the minimum of the conduction band are both situated at the YA center.
RESUMEN
In the pursuit of sustainable porcelain production, this research examines the potential of using recovered automotive glass as a substitute for traditional feldspar, specifically feldspar imported from Spain. Porcelain samples were sintered at different temperatures and with varied proportions of automotive glass. The crystalline phases formed post-sintering were determined through X-ray diffraction and quantified by dissolving the porcelain in concentrated hydrofluoric acid. Results revealed that the inclusion of automotive glass, owing to its dissolved oxide content, accelerated the porcelain melting process and led to an increase in the vitreous phase. Notably, anorthite phases became dominant and mullite formation was evident at 1100 °C, stabilizing in samples G00 and G10, and then increasing at 1200 °C due to the emergence of secondary mullite. This secondary mullite forms from the residual silica after the primary mullite formation and the aluminium in the feldspars, which is about 17 %. For samples G20 and G30, only primary mullite was observed due to the decreased aluminium content resultant from feldspar replacement by glass. These findings underscore the viability of automotive glass in porcelain production, providing a sustainable and effective alternative to feldspar.
RESUMEN
Some physical properties of hexahalometallate K2XBr6(X = Se, Pt) were computed in the zinc blend structure using GGA-PBESOL. The cell constant of K2SeBr6 and K2PtBr6 is consistent to the experiment value quoted in the literature, where the error is 0.95% and 1%. K2SeBr6 and K2PtBr6 present covalent bonding, high anisotropy and are ductile. The elastic constants of K2SeBr6 and K2PtBr6 are significantly smaller due to their larger reticular distances, lower Coulomb forces and then they are soft and damage tolerant. The interatomic separation is greater in K2SeBr6 than in K2PtBr6, hence the Coulomb interaction in K2PtBr6 is greater than that of K2SeBr6. The internal coordinate of Br atom in K2PtBr6 is lower than that of the same atom in K2SeBr6, and this can be explained by the fact that it is inversely proportional to the atom radius of Se and Pt. There are two major plasmonic processes, with intensities 3.7 and 1.35 located around 53.5 nm and 72.8 nm for K2SeBr6 and K2PtBr6.
RESUMEN
The GGA functional PW91 were used in order to predict the structural, electronic, optical and elastic properties of α and ß of d- Glucose. Such compounds, in their solid form, are widely used in chemical and pharmaceutical industry. The pure crystalline forms of glucose α-d-glucose and ß-d-glucose have the same space group (McDonald and Beevers, 1950) [1]. We note that despite the fact that the two compounds have the same space group, upon cooling, the interatomic distances change and a new compound occurs. On the other hand, the cooling also influences the physical properties (structural, elastic, electronic and optical properties). The objective of this paper is associated with the control of the physical states of molecular materials when they are subjected to polymorphic changes. The laws and physical parameters that govern these transformations remain fundamentally misunderstood.
