The BaF2-BiF3 system was studied by the method of coprecipitation from aqueous solutions. The region of precipitation of single-phase nonoxygen powders was revealed (the atomic fraction of Bi in the initial solution was 0.35–0.43). The composition of the cubic fluorite-type phase is BaBiF5 according to an energy-dispersive X-ray spectroscopy analysis. Samples prepared from solutions with high Bi concentrations contain oxygen. This indicates that the hydrolysis temperature of BiF3 decreases when compared with that of the bulk samples and that this process takes place at room temperature. The coherent intergrowth of nanoparticles with the formation of single crystals with nonfaceted complex forms was shown by scanning electron microscopy and transmission electron microscopy.

Reactions of solutions of yttrium oxide in nitric acid with a 1.67 M NH4HCO3 solution were studied by direct and back titration. When the concentration of the reacting solution was within 0.031–0.052 mol/L (as Y2O3), yttrium carbonate Y2(CO3)3 · nH2O (n ≈ 2.5) of fibrous or spherulitic morphology precipitated. When the concentration was decreased to 0.022 mol/L, a new phase of platy morphology appeared. Heating these precipitates to 650–680°C yielded yttrium oxide having coherent scattering domain sizes of 40–80 nm. Y2O3 particles retain the precursor morphology.

С использованием прямого и обратного титрования исследовано взаимодействие растворов оксида иттрия в азотной кислоте с 1.67 М раствором NH4HCO3. При концентрации исходного раствора 0.031–0.052 моль/л (в расчете на Y2O3) в осадок выпадает карбонат иттрия Y2(CO3)3 · nH2O (n 2.5) волокнистой или сферолитной морфологии. При уменьшении концентрации до 0.022 моль/л образуется новая фаза пластинчатой морфологии. Нагревание осадков до 650–680°С приводит к образованию оксида иттрия с размером областей когерентного рассеяния 40–80 нм. Частицы Y2O3 сохраняют морфологию прекурсоров.

The kinetics of the topochemical reaction of methane dehydrogenation was studied using TRUMEM ultrafiltration membranes (TiO2 + Cr2O3 on porous steel, the size of transport pores 50 nm). The depth of the deposition of pyrocarbon nanocrystallites (PNC) into pores was determined. The depth of PNC deposition was estimated using scanning electron microscopy and high-resolution energy-dispersion spectrometry. The deposition of PNC at a 4.9 kPa methane pressure in the reaction zone created Knudsen conditions for methane diffusion in pores. The deposition of PNC therefore occurred over the whole area of pore surfaces. Studies of the kinetics of PNC formation on the surface of pores showed that reaction rate V and its constant k substantially depended on reaction duration. The influence of PNC deposition on the electrosurface properties and permeability of the membranes to ethanol and dodecane was studied. After the deposition of PNC with L c = 1.0–1.1 nm on the surface of pores, the ζ-potential and surface charge density (σ) decreased; simultaneously, the efficiency with respect to ethanol increased.