Glass containing chromium is a promising material for use in various modern fields of application (laser technology, optoelectronic devices, and luminescent resources). Chromium oxides are well-known nucleating agents that can cause crystallization. One of the most commonly observed crystalline phases in silicate glasses is cristobalite, which lowers their mechanical strength, leading to the destruction of the material. The objective of this investigation was to study in detail the crystallization of cristobalite in sodium borosilicate glass in the presence of 2 mol% Cr₂O₃, depending on the thermal history of the glass. The glass was studied using XRD, SEM, EPR, FTIR-spectroscopy, XPS, and solid-state NMR. Eskolaite, α-Cr₂O₃, which had crystallized in this glass, stimulated the bulk crystallization of cristobalite at 550 °C after isothermally treating it for 72 h, due to the phase-separated structure of the glass with its interpenetrating phase morphology. Polytypism, resulting in the incorporation of alkalis into the cristobalite structure, was observed. Cr₂O₃ causes the catalytic crystallization of cristobalite at an extremely low temperature, which is at lower concentrations and temperatures than in glass containing Fe₂O₃ with a similar composition. The crystal growth rate and the incubation time for the crystallization of cristobalite were roughly estimated.

Samples of Chernobyl fuel debris, including massive corium and “lava” were collected inside the Chernobyl “Sarcophagus” or “Shelter” in 1990, transported to Leningrad (St. Petersburg) and stored under laboratory conditions for many years. In 2011 aged samples were visually re-examined and it was confirmed that most of them remained intact, although some evidence of self-destruction and chemical alteration were clearly observed. Selected samples of corium and “lava” were affected by static leaching at temperatures of 25, 90 and 150 °C in distilled water. A normalized Pu mass loss (NL_Pu) from corium samples after 140 days was noted to be 0.5 g/m² at 25 °C and 1.1 g/m² at 90 °C. For “lava” samples NL_Pu was 2.2–2.3 g/m² at 90 °C for 140 days. The formation of secondary uranyl phases on the surface of corium and “lava” samples altered at 150 °C was confirmed. The results obtained are considered as an important basis for the simulation of fuel debris aging at Fukushima Daiichi nuclear power plant (NPP).

The spatial spin-modulated structure in BiFeO₃ is retained and the anharmonicity parameter decreases with crystallite size decreasing, followed by a change in the anisotropy type from an “easy axis” to an “easy plane” at about 50 nm.

The paper presents the results of studies of the technologically significant properties of municipal solid waste (MSW) compost produced by MSW processing enterprises in St. Petersburg (Russia) where the Dano drum process is implemented. The chemical and microbiological composition of compost, as well as heat during ripening, are investigated. The chemical composition of industrial compost produced in St. Petersburg does not make it possible to use it as fertilizers and soil in agriculture. From the microbiological point of view, NSW compost is not dangerous, but the content of indicator groups of microorganisms classifies it as contaminated soil. The heat generation of compost during ripening is uneven - the largest share of heat 78.5% is released in the first year of maturation. In absolute terms, this value is 3250 kJ/kg by dry weight. To ensure the process is carried out during a period when the compost temperature is higher than the ambient temperature, toxic substances must be added to the compost in an amount not more than 400 times the pollutant content in waste of the 4th hazardclass.