The phase transformations and crystalline phases precipitated in powders of quenched glasses similar in composition to Li–aegirine (LiFeSi2O6) subjected to heat treatment in the temperature range of 600–1000°C, are studied by differential scaning calorimetry (DSC) and X-ray diffraction analysis (XRD). The formation of a low-temperature metastable hexagonal lithium–iron silicate crystalline phase with a β-quartz structure is demonstrated for the first time. The conditions for obtaining this phase and the electrochemical properties of the developed material are discussed. In the first charge–discharge cycle, the cell containing a crystalline phase with a β-quartz structure as the anode has a specific capacity of 400 mAh/g, which is more than one-and-a-half times higher than this value for the monoclinic modification of Li–aegirine.
Glass formation in the As–Se–SbBr3 system is studied. Glasses are synthesized by melting a batch of As, Se, and SbBr3 at a temperature of 700°C. The density of the glasses and optical absorption in the IR region of the spectrum are measured. The glass transition and crystallization temperatures are determined using differential thermal analysis (DTA). The structure of the glasses is studied using Raman spectroscopy. It is proposed that antimony bromide enters the glass as isolated molecules, without exchanging bromine with arsenic selenide. The studied glasses are promising for the production of low-melting IR adhesives, lenses, and windows for various IR optoelectronic devices using the precise pressing method.
Time series of acoustic emission (AE) pulses are excited by dropping a load onto samples of ductile-brittle ZnS and ZnSe ceramics. AE activity is recorded in two frequency windows of 100–200 and 400–800 kHz. In both ceramics, low-frequency emission occurred from the moment the load is applied; the high-frequency signal appears with a time delay of 100–150 μs. Statistical analysis of the pulse series reveals a qualitative difference in emissions in the specified frequency zones. The energy distribution of pulses emitted in the 100–200 kHz range follows a random poissonian-type dependence, whereas the AE series in the 400–800 kHz range shows a correlated accumulation of microdamage. Activity in the low-frequency region appears at the initial stage of failure (plastic flow) and is attributed to dislocation glide. When the ultimate deformation is reached, a brittle accumulation of interacting microcracks occurs. The described procedure for analyzing the process of damage development under impact loading allows one to determine the transition point from the disordered degradation of the structure of ductile-brittle materials to cooperative, brittle destruction.
It is established that the ZnO–Al2O3 oxide coating formed on the surface of aluminosilicate fibers contains hexagonal 13-nm ZnO crystals. The obtained composites demonstrate intense generation of singlet oxygen under the influence of UV radiation. Increasing the radiation power density provided a significant increase (+60
The photodynamic inactivation of viruses by a microporous photocatalytic element made of copper or copper alloy is the very method of ensuring biosafety that the article is about. Based on this method, encouraging results of virological studies (using the influenza virus as a test) were obtained as well as the equipment solving the strategic task of antiviral (influenza, COVID-19, etc.) disinfecting and sterilizing of confined spaces air, including air of medical premises, was developed. Keywords: air sterilization, copper, microporous membrane, influenza virus, singlet oxigen.
