Materials Science Forum Vol. 1165

Abstract: Silicophosphate coatings are one of the current vectors in the field of increasing the fire resistance of extruded polystyrene foam (XPS), which is widely used in construction as a thermal insulation material. The article presents a study of the effectiveness of fire-retardant coatings based on silicic acid sols modified with orthophosphoric acid and phosphate buffer solutions. The effect of phosphorus-containing additives on the rheological properties of the compositions was determined spectrophotometrically. The highest survival rates (~2 h) were observed in sols containing phosphate buffer solutions. Using differential thermal analysis, the influence of phosphate additives on the nature of polycondensation of polysilicic acid formed during the creation of a fire-retardant composition based on aqueous solutions of liquid glass and acetic acid was established and confirmed by infrared spectroscopy. The addition of orthophosphoric acid contributes to the formation of network silicate structures that slowly decompose under the influence of temperature with a minimal increase in mass loss, which is a guarantee of preserving the integrity of the coating. However, the results of fire studies of coatings with orthophosphoric acid additives did not give a stable positive result, so in further studies, phosphate salts of alkali metals were used in the form of phosphate buffer pairs. Phosphate ions are able to be incorporated into the structure of the siloxane framework of polysilicic acid, increasing its fire resistance, which was confirmed by IR spectroscopy. The use of phosphate buffer solutions is more promising, because, firstly, it provides increased survivability of the composition and, secondly, it promotes melting of the coating under the influence of fire, therefore, during shrinkage of polystyrene foam, the coating changes its shape without the formation of cracks and reliably protects the finishing material from fire. Conducting fire tests made it possible to establish that all the studied compositions are able to eliminate the main disadvantage of polystyrene foam combustion - the formation of burning drops. It was established that the use of potassium phosphate salts provided the best fire protection for extruded polystyrene foam, which was confirmed by fire tests and microscopic examination of the material of different grades.

Abstract: The construction, operating principles, and Li-ion battery thermal runaway mechanisms were analyzed. The external mechanical damage to a Li-ion battery with the uncontrolled thermal runaway development was investigated. The battery self-heating temperature regime was determined. A possible reactions set leading to intense materials self-heating and decomposition was considered. The battery self-heating stopping by immersing it in a container with a water excess relative to the stoichiometric amount for the lithium metal maximum mass that can accumulate was investigated. The change in resulting aqueous solution pH was measured, and the hydrogen release was also recorded. Reaction completion time dependences was established. The water required amount to absorb the heat that could be released during the reaction was calculated, which correlated with the experimental data. Possible measures to Li-ion batteries prevent and stop the burning were considered.

Abstract: In the presented work the features of formation of metal-fullerene films of the systems Al-C₆₀, Au-C₆₀, Cu-C₆₀, Ti-C₆₀ from atomic-molecular flows in vacuum were investigated, the processes of surface resonance plasmon absorption and diffusion were studied. It is shown that electron microscopy, optical, Auger-electron and X-ray spectroscopy methods are effective for the study of metal-fullerene films. The combination of different methods of spectroscopy and electron microscopy allowed to establish the dependence of the grain size of the films, the shift of the position of the plasmon absorption maximum, diffusion parameters on the ratio of metal and fullerene components, to establish the fact of formation of the chemical compound Cu₆C₆₀.

Abstract: Herein, the lithium yttrium fluoride (LiYF4) compound doped with rare-earth Nd3+ ions are synthesized by solid-state reaction methods. The results of XRD, optical absorption, and emission measurements confirm that the doped powder sample was successfully synthesized. The optical properties of Nd-doped LiYF₄ powder samples were investigated through a comparison of ab initio and experimental methods. We predicted the crystal and electronic structures using ab initio total energy calculations within the framework of density functional theory (DFT). Our results for the optical properties, including the dielectric function, absorption coefficient, and refractive index of the Nd-doped LiYF₄ compound, were calculated and compared using the independent particle approximation (IPA), time-dependent density functional perturbation theory (TDDFpT), and random phase approximation (RPA).

Abstract: Mongolia is one of the countries with the highest prevalence of Hepatitis Delta Virus (HDV). A 2023 study showed that in rural areas of Mongolia, the HDV prevalence rate was 65%. Therefore, implementing low-cost diagnostic methods for early detection of HDV in Mongolia would be important. A novel setup was designed and assembled, using Surface Plasmon Resonance (SPR), to measure the spectra minimums of gold thin film which contained four samples, including HDV-positive and HDV-negative serum. Relative to gold thin film and antigen, HDV-negative and HDV-positive samples exhibited a shift in the SPR spectra minimum. These results demonstrate that this SPR effect could serve as a relatively rapid and cost-effective diagnostic method for detecting the presence of HDV in blood serum samples on gold thin film surfaces.