Tungstate Based Ceramics Obtained By Spark Plasma Sintering Method – Possible Material for Consolidation of Radioactive Wastes’ Components

The Spark Plasma Sintering method was used to produce high-density ceramics from tungstates SrWO4 and NaNd(WO4)2 with scheelite structure. These compounds are proposed as possible matrices for the consolidation of radwaste components. Powder samples were obtained by coprecipitation method and studied by X-ray diffraction analysis (XRD) and scanning electron microscopy (SEM). After sintering, the samples retained their phase identity (scheelite structure). The total duration of sintering was ∼ 13-15 min, the relative density was reached ∼ 92, 99%. Keywords: Tungstates, RW, Spark Plasma Sintering, high density, microstructur

Investigation of the microstructure of the fine-grained YPO4_4:Gd ceramics with xenotime structure after Xe irradiation

The paper reports on the preparation of xenotime-structured ceramics by the Spark Plasma Sintering (SPS) method. Phosphates Y$_{0.95}$Gd$_{0.05}$PO$_4$ (YPO$_4$:Gd) were obtained by the sol-gel method. The synthesized nanopowders are collected in large agglomerates 10-50 mkm in size. Ceramics has a fine-grained microstructure and a high relative density (98.67%). The total time of the SPS process was approximately 18 min. High-density sintered ceramics YPO$_4$:Gd with a xenotime structure were irradiated with Xe$^{+26}$ ions (E = 167 MeV) to fluences of $1\times10^{12}$-$3\times 10^{13}$ cm$^{-2}$. Complete amorphization at maximum fluence was not achieved. As the fluence increases, an insignificant increase in the depth of the amorphous layer is observed. According to the results of grazing incidence XRD (GIXRD), with an increase in fluence from $1\times10^{12}$-$3\times 10^{13}$ cm$^{-2}$, an increase in the volume fraction of the amorphous structure from 20 to 70% is observed. The intensity of XRD peak 200 YPO$_4$:Gd after recovery annealing (700$^\circ$C, 18 h) reached a value of ~80% of the initial intensity I0.Comment: 16 pages, 10 figure

X-Ray Diffraction Analysis of Ceramics Irradiated with High-Energy Ions

NaNd(WO4)2 and NaNd(MoO4)2 ceramic samples subjected to ion implantation is considered. The degree of amorphization of the near-surface layer of the samples depending on the fluence were obtained. The depth of the amorphized layer was also investigated.Рентгенодифракционные исследования образцов до и после облучения выполнялись в лаборатории диагностики радиационных дефектов в твердотельных наноструктурах ИФМ РАН при поддержке Министерства науки и высшего образования РФ (г/з № 0030-2021-0030). Исследование выполнено при финансовой поддержке РФФИ в рамках научного проекта №20-21-00145_Росатом

CHARACTERISTICS OF SUPERCAPACITORS ELECTRODES BASED ON TITANIA AND CARBON NANOTUBES

TiO2-NT and CNT based electrodes have been fabricated by anodizing and pyrolysis and characterized by scanning electron microscope. Electrochemical performances such as spe-cific capacitance, energy and power have been calculated in frame of the galvanostatic charge-discharge curves analysis.Исследование выполнено в рамках инициативного научного проекта FEUZ-2020-0059 Минобрнауки РФ

Advances in ITER-relevant Nb-Ti and Nb3_{3}Sn strands and low-loss Nb-Ti strands in RF

The review of the main results of R&D directed on the enhancement of ITER relevant NbTi and Nb$_{3}$Sn strands performance recently carried out in Russia (the Bochvar Institute) are presented. For ITER PF type (NbTi) strands with Cu/non Cu ratio of 1.6 the attainment of ITER specified critical current density (Jc) ≥ 2900 A/mm2 (5 T, 4.2 K) has been shown. For Toroidal Field (TF) strands (Nb$_{3}$Sn) the influence of doping and layout peculiarities of the wires produced by bronze method on their current-carrying ability has been investigated. It was shown that with non-doped matrix and doped filaments Jc exceeds 800 A/mm2 (12 T, 4.2 K) while with the application of the doped bronze and nondoped filaments it exceeds 900 A/mm2. Internal-tin Nb$_{3}$Sn strand meeting the ITER TF specification requirements was also developed and fabricated. The results of testing of CICC samples in a SULTAN facility have shown that performance parameters are higher than ITER qualification requirements Low loss model fine filament NbTi strands, intended for operating in fields with a ramp rate from 1 up to 4 T/s, has been developed and manufactured. The use of commercial MN-5 alloy (Cu-5wt.%Ni) and the Cu- 0.5wt.%Mn alloy for matrix of strands are discussed. The critical current density higher than 2700 A/mm2 (5 T, 4.2 K was shown to be attainable

DEVELOPMENT OF A TECHNIQUE FOR DETERMINING CADMIUM, LEAD, ARSENIC WITH THE ETAAS METHOD IN MEDICINAL PLANT RAW MATERIALS

Electrothermal atomic absorption spectrometry (ETAAS) is one of the most well-known methods for determining trace amounts of elements in natural objects, since it is simple in instrumentation and rather cheap. It is especially promising for the pharmaceutical analysis of medicinal plant raw materials for quality control purposes. A new unified ETAAS technique for the determination of cadmium, lead and arsenic in solutions obtained after acid decomposition (with HNO3) of plant raw material under microwave heating conditions has been developed. It was shown that cadmium can be determined without a modifier, while for lead and arsenic the presence of a modifier is necessary. Inexpensive and widely available substances were proposed as modifiers: 1% solution of ascorbic acid (for lead), 1% solution of Ni(NO3)(2) (for arsenic), which were previously used in the Russian Federation exclusively in geochemical studies. The conditions for the preparation of the analysed samples are proposed. The using prospects of the developed technique for the natural substances quality control, as well as its universality for the analysis of plant raw material of various morphological groups have been demonstrated. The technique was validated in terms of specificity, accuracy, precision, repeatability, linearity, range, robustness. The technique can be recommended for determination of these ecotoxicants accumulation in wild-growing and cultivated medicinal plants

Latent myocardial damage after cardiopulmonary resuscitation in a teenager without prior cardiac disease

Cardiopulmonary resuscitation is an integral part of intensive care in children and adolescents with a number of diseases, most commonly with congenital heart disease, critical cardiac arrhythmias, or severe traumas. This procedure can cause a number of complications, most of them are still completely unstudied, and many of them are associated with the underlying disease. We have a unique case report of a 14-year-old boy without any cardiac disease, who underwent extensive resuscitative measures, including closed-chest massage, tracheal intubation with mechanical ventilation, as well as a few electrical defibrillations with transient myocardial injury

Thermal expansion of scheelite-like molybdate powders and ceramics

NaxSr1 – 2xNdxMoO4 (x = 0–0.5, Δx = 0.1) solid solutions with the scheelite structure have been synthesized for the first time and their crystallographic parameters have been determined as functions of composition and temperature. Their thermal expansion coefficients have been determined in the temperature range 25–1000°C: αa = (12.9–14.9) × 10–6 °C–1 and αc = (24.9–25.9) × 10–6 °C–1. Using spark plasma sintering at tmax ≈ 872–985°C and τ ≈ 650–750 s, we have prepared ceramics with relative densities in the range 97–99%.This work was supported by the Russian Science Foundation, project no. 16-13-10464: Promising Mineral-Like Ceramic Materials with Improved and Controlled Functional Characteristics: Development, Synthesis, and Characterization