In this paper we synthesized high entropy oxide system (Sc_0.2Ce_0.2Pr_0.2Gd_0.2Ho_0.2)₂O_3±δ by precipitation of hydroxides from REE nitrates aqueous solutions and annealing the mixture at 800 °C. It is possible to obtain the various forms of simple and complex composition based on the rare earth oxides, including oxides in the form of nanosized powders. The main idea of obtaining HEOS comes from the field of high-entropy alloys. The interconnection between configurational entropy and mixing enthalpy is a key factor for determining phase transformations. The phase composition, structure, and surface morphology of the obtained powders were investigated by scanning electron microscopy and X-ray phase analysis methods.

In this paper, the possibility of obtaining fine zirconium powders by the hydrogenation-dehydrogenation method is studied. The main parameters of the technological process that allow obtaining fine zirconium powders for pyrotechnics are determined. Hydrogenation and dehydrogenation of the samples are carried out in a rotating quartz tube placed in a furnace at temperatures of 380 degrees C and 850 degrees C, respectively. Zirconium hydride is milled using tungsten carbide balls to eliminate the presence of impurities. Thus it is possible to obtain a fine zirconium powder with a number-average particle size of 4.527 +/- 2.650 mu m and a specific surface area of 0.231 m(2)/g from the initial electrolytic zirconium powder with a number-average particle size of 220 mu m and a specific surface area < 0.1 m(2)/g. The allowed relative error of measuring the specific surface area is +/- 5%. Hence it is possible to reduce the particle size of zirconium powder by 54.6 times without changing the composition.

The possibility of enrichment and radioactivity reduction of zirconium concentrate obtained at the Obukhovsky mining and processing plant, located in the North Kazakhstan region, was investigated. The zircon concentrate was enriched and deactivated by dry magnetic separation and centrifugal air separation. The elements distribution over the grain surface of the obtained fractions was studied and the particle size distribution was determined by energy dispersive X-ray spectroscopy. The characteristics of the initial zircon concentrate were determined. The average particle size was 70 µm, the bulk density was 2.21 g/cm³, the true density was 4.05 g/cm³, the activity was 10.3 ± 0.6 kBq/kg, and the ZrO2 content was 44.85 wt.%. Dry magnetic separation was carried out at a magnetic induction value of 1.3 T in the separator working area and a feed rate of 5 g/min. Centrifugal air separation was carried out using a rotary classifier at rotor speeds of 3000, 980, and 600 rpm, consuming 2000 Nm³ of air per hour and a concentrate flow of 20 kg/h. The scheme of zircon concentrate processing to produce three final products was proposed. The first is the zircon concentrate having a low activity (ZrO₂ content = 55.4 wt.%, P = 5.8 ± 0.6 kBq/kg). The second is the titanium-containing fraction having a low zirconium content (ZrO₂ content = 17.7 wt.%, P = 14.2 ± 0.6 kBq/kg). The third is the concentrate having a considerable zirconium content and high activity (ZrO₂ content = 23.5 wt.%, P = 12.8 ± 0.6 kBq/kg).

The manuscript describes the phase composition, microstructure, some physical and mechanical properties of the Ti-Al system with addition of 2 at. % Dy (TAD) and Ho (TAH) obtained by “hydride technology”. Phase diagrams for Ti-Al-Dy and Ti-Al-Ho at a temperature of 1150 °C and basic properties for ternary phases Dy₆Ti₄Al₄₃ and Ho₆Ti₄Al₄₃ were calculated. A crystallographic database of stable and quasistable structures of the known elemental composition was created in the USPEX-SIESTA software by means of an evolutionary code. The calculations show that adding REM leads to a significant stabilizing effect in each Ti-Al-Me (Me = Dy, Ho) system without exception. It has been established that the lattice energies of AlTi₃Ho and AlTi₃Dy are, respectively, equal to: EAl₄Ti₁₂Dy₃ = −32,877.825 eV and EAl₄Ti₁₂Dy₃ = −31,227.561 eV. In the synthesized Ti₄₉Al₄₉Ho₂ compound, the main phases include Al-Ti, Al₃Ti₃ and Al₄Ti₁₂Ho₃ and the contributions to the theoretical intensity are equal to 44.83, 44.43 and 5.55%, respectively. Ti₄₉Al₄₉Dy₂ is dominated by the Al-Ti, Al₃Ti₃ and Al₄Ti₁₂Dy phases, whose contributions are equal to 65.04, 16.88 and 11.2%, respectively. The microhardness of TAD and TAN specimens is 1.61 ± 0.08 and 1.47 ± 0.07 GPa, respectively.

The present work analyzes the specimens of orthite (allanite) mineral ores obtained from the Vernadsky mine (Slyudyanka River, Irkutsk region) and Yuzhno-Bogatyrskoye occurrence (Kuznetsk Alatau). The elemental chemical composition of the ore was determined by electronic microscopy of the specimen’s surface. The study establishes that uranium and thorium in orthite ores of the Yuzhno-Bogatyrskoye occurrence are mainly represented by their separate minerals, while the content of the orthite phase in the form of their isomorphic inclusion is small.