Industrial technologies that employ fast heating and cooling of surface layers of articles for their hardening are widely applied nowadays. For many steel grades, the duration of thermal pulse should be less than 1 ms. Data on the experimental determination of this technological parameter are lacking; therefore, in the work presented, a method is proposed that serves to solve this task via investigation of diffusion of light elements into steel directly in the course of surface treatment. The application of diffusion method is favored by the presence in the atmosphere of oxygen, nitrogen, carbon, and hydrogen atoms upon treatment of the article surface, their diffusion coefficients in iron and steels at high temperatures, strong temperature dependence of the diffusion coefficients, characteristic values of the critical quenching rate for steels, metrological characteristics of nuclear -reaction -based methods and secondary ion -mass spectrometry upon studying diffusion in solids, and other factors. Approbation of this method was carried out based on the data on nitrogen diffusion gained by the method of nuclear reactions. Steel specimens were modified with argon plasma; the plasma source worked in the stationary mode and pulse heating and cooling of the surface were performed by moving plasma torch across the specimen surface. Such technology provides hardening of steel specimens at a depth of about 1 mm and the duration of thermal pulse obtained by diffusion method was less than 1 ms. The diffusion method is promising for characterization of surface treatment technologies for steel items using plasma, high frequency currents, and laser irradiation.

The data on the influence of point defects on the rate of hydrogen tunneling in a crystal lattice of a solid have been obtained for the first time. It is established that vacancies in indium of no more than 0.1 at. % increase the coefficients of quantum diffusion of deuterium by a factor of 30. The vacancies were produced by irradiation of specimens with deuterons; the diffusion coefficients were determined in the temperature range from liquid nitrogen to 125 K using the accelerating technique of nuclear reactions; the type of defects affecting the tunneling rate was identified by the method of isochronous annealings. The results are discussed in the model of quantum diffusion proposed by Flynn and Stoneham for light interstitial atoms in metals. The strong accelerating impact of vacancies on the tunneling rate is traceable to a decrease in the distance between equilibrium positions for deuterium atoms in the crystal lattice.

Diffusion of deuterium in indium is studied herein. In the temperature range 200–350 K, mass transfer is controlled predominantly by the mechanism of overbarrier atomic jumps; at temperatures from 80 to 120 K, by tunneling; whereas in the range from 120 to 200 K, there takes place a gradual transition from one migration mechanism to the other. These results are of fundamental significance since it is shown for the first time that quantum diffusion can be observed in a metal with a crystal lattice other than the body centered cubic one. Conditions are specified that are necessary for the observation of quantum diffusion of hydrogen: low values of Debye temperature, density of atomic packing in the lattice, and distance between the nearest equilibrium positions of hydrogen atoms. Moreover, data on the influence of point defects on hydrogen tunneling in solids are gained for the first time as well. The quantum diffusion coefficient is twice as high in the sample with enhanced vacancy concentration.

The composition, structure and corrosion behaviour of CrxAly(SOC coatings fabricated by the arc discharge techniques using Cr-Al-Si and graphite cathodes were studied. X-ray photoelectron spectroscopy, X-ray energy-dispersive spectroscopy, nuclear reactions, and Rutherford backscattering methods were applied to determine composition of the coating, X-ray diffraction and transmission electron microscopy - to investigate the structure of the coating. Corrosion tests were performed in an electrochemical cell in a 3.5%NaCl solution. Depletion of the cathode surface of chromium, screening of Cr+ by C+ in plasma, and selective etching of the coating upper layers are accompanied by a decrease of Cr/(Al +Si) ratio in the coatings compared to the cathode. The carbon content (C-C) in CrxAl(Si)(y)C, determined by XPS, EDS and NR, differs by several times. The C-C, measured by NR correlates with the results of Raman spectroscopy and confirms the existence of a continuous carbon matrix in CrxAly(Si)C. Cr is chemical bonded with carbon, silicon - with carbon and aluminum. The Al-Si system provides the structure feature of CrxAl(Si)(y)C: a network of aluminum intersects the amorphous matrix. The mechanical mismatch and weak bond between the Al structures and the amorphous matrix may be the reason for the formation of defects in the form of cracks and microchannels along the boundaries.

A new class of brain tyrosine hydroxylase inhibitors, the 5-halotryptophans, are described. In decreasing order of activity the series goes iodo, bromo, chloro and fluoro. The 5-halotryptophans compare in potency, by invitro assay on crude homogenate, with the most active previously described tyrosine hydroxylase inhibitors. One member of the series, DL-5-bromotryptophan was compared invivo with L-α-methyl-p-tyrosine. Both compounds significantly lowered brain and heart noradrenaline content. L-α-Methyl-p-tyrosine was more effective at lowering tissue noradrenalin even though the inhibition of tyrosine hydroxylase as measured by the invitro assays was not as prolonged as with DL-5-bromotryptophan.

Oxide nanopowders are widely used in engineering, and their properties are largely controlled by the defect structure of nanoparticles. Experimental data on the spatial distribution of defects in oxide nanoparticles are unavailable in the literature, and in the work presented, to gain such information, methods of nuclear reactions and deuterium probes were employed. The object of study was oxygen-deficient defects in TiO2 nanoparticles. Nanopowders were synthesized by the sol–gel method and laser evaporation of ceramic targets. To modify the defect structure in nanoparticles, nanopowders were subjected to vacuum annealings. It was established that in TiO2 nanoparticles there form two-dimensional defects consisting of six titanium atoms that occupy the nanoparticle surface and result in a remarkable deviation of the chemical composition from the stoichiometry. The presence of such defects was observed in two cases: in TiO2 nanoparticles alloyed with cobalt, which were synthesized by the sol–gel method, and in nonalloyed TiO2 nanoparticles synthesized by laser evaporation of ceramic target. The concentration of the defects under study can be varied in wide limits via vacuum annealings of nanopowders which can provide formation on the surface of oxide nanoparticles of a solid film of titanium atoms 1–2 monolayers in thickness.

Reduction of ZrO2 by lithium during electrolysis of LiCl-KCl-Li2O melt at 650 °C was studied using a set of physicochemical methods of analysis. Influence of ZrO2 in the space near a molybdenum cathode on the kinetics of the cathode process was established. Possible variations of the electrode reaction associated with the zirconium reduction were proposed. The appearance of ZrO2 in the cathode space resulted in consumption of reduced lithium and in increase in the potential relaxation time of the molybdenum cathode after cathode polarization. Long-term galvanic impulse electrolysis of LiCl-KCl-Li2O melt at 650 °C was carried out using the molybdenum cathode which was immersed into the ZrO2 powder. According to the X-ray fluorescence analysis as well as the method of nuclear reactions the reduction product was presented by the ZrO2, Li2ZrO3, Zr3O phases. Additionally, by alloying the reduction product with tin, the ZrO2 reduction degree to metallic zirconium was estimated, which was close to zero. It was assumed that the main pathway for the appearance of the metallic zirconium in the ZrO2 reduction product during electrolysis of the LiCl-KCl-Li2O melt was direct electroreduction of dissolved zirconium in the melt.

Solid solution $${\text{G}}{{{\text{d}}}_{{2 - x}}}{\text{L}}{{{\text{i}}}_{x}}{\text{Z}}{{{\text{r}}}_{2}}{{{\text{O}}}_{{7 - x}}}$$ with a pyrochlore structure is synthesized for the first time. The cationic composition is confirmed via chemical analysis and nuclear reactions. It is found that the stoichiometry with respect to lithium is retained up to 1100°C. The lattice parameter diminishes in the homogeneity range 0 ≤ x ≤ 0.30, while the free volume of migration grows. Introducing lithium into the Gd sublattice raises oxygen–ion conductivity, due to the emergence of oxygen vacancies and enhancement of their mobility. Maximum conductivity is reached for composition with х = 0.10 (~1 × 10−3 Ω−1 cm−1, 650°C). An assumption is made about the formation of associates of the type $${{\{ {\text{Li}}_{{{\text{Gd}}}}^{{''}} \cdot {\text{V}}_{{\text{o}}}^{{ \bullet \bullet }}\} }^{ \times }}$$ at high contents of the dopant (x = 0.30), accompanied by an increase in the activation energy of conductivity.

The pyrochlore Gd1.55Li0.45Zr2O6.55 was prepared by the solution and solid-state methods. The introduction of lithium in the Gd-sublattice led to decrease in the lattice parameter a = 10.4830(8) Å in comparison with Gd2Zr2O7 (a =10.5346(2) Å). Monitoring of the lithium content in the sample during heat treatments showed a loss of lithium at temperatures above 1100 °C, so, to maintain the stoichiometry of lithium the low temperature sintering methods are required. The sample Gd1.55Li0.45Zr2O6.55 exhibited a predominant oxygen-ion transport over a wide range of temperatures. Although doping did not lead to an increase in the oxygen-ion conductivity compared to Gd2Zr2O7, it caused the suppression of the hole conductivity.

The method of using deuterium probes was proposed for studying the defect structure of oxide nanoparticles. It was based on the fact that in the course of annealing nanoparticles in deuterium, clusters consisting of point defects and deuterium atoms are formed. The content of the clusters depended on the type of defects. The concentration of deuterium and the content of the clusters were determined by the method of nuclear reactions. The technique was applied to study the defect structures of the nanoparticles of YSZ10, cubic zirconium dioxide doped with yttrium, and TiO2. The nanopowders of YSZ10 and TiO2 were synthesized by means of the laser evaporation of the ceramic target; besides, TiO2 was obtained using the sol-gel method. It was shown that the method of the use of deuterium probes allowed one to reveal the presence of one or several types of point defects in nanoparticles and determine their concentration in the bulk and near the surface of nanoparticles with an accuracy of several percent and sensitivity of about 0.01 at%.

The acceleration method of nuclear reactions is used to measure the content of lithium and oxygen in zirconium oxides. The purpose of the study stems from the fact that there are no direct methods for determining lithium concentration in solids, while lithium is currently widely used for alloying alloys in aircraft construction, nuclear power engineering, electrochemical devices, and other fields of technology. It is shown that satisfactory metrological characteristics of the method are provided when using the 6Li(d, p0)7Li and 7Li(d, p)8Li reactions at a deuteron energy of 650 keV.

A device has been developed for isothermal sample annealing in the chamber of an accelerator facility. The application of the nuclear reaction analysis is allowed during the sample annealing. Flowing liquid nitrogen and a resistive heater are used for the sample cooling and heating. Using the device, sample annealing is carried out in the temperature range of 110–500 K and the temperature is maintained with an accuracy of 1 K. The obtained characteristics meet the requirements of precision experiments on deuterium diffusion in solids, including at cryogenic temperatures.

The construction of a hermetic transport container for mounting alkaline metal samples in the vacuum chamber of an accelerator during online measurements of the deuterium diffusion coefficients in metals is described. A glass capsule containing an alkaline metal sample is unsealed in a special box with an inert gas atmosphere and the sample is placed in a cylindrical hollow at the surface of a flat metal plate of the container. After this, the hermetic transport container with the sample is fixed in place on a stationary holder inside the accelerator chamber and is unsealed after a high vacuum is attained in the chamber. Sodium samples are assessed using the nuclear reaction analysis. It is shown that the sodium purity in oxygen, carbon, and other low-Z elements meets the requirements of the accelerator technique.

The online nuclear reaction analysis technique has been applied to study the temperature dependence of deuterium diffusion coefficients for deuterium in sodium at temperatures ranging between 110 and 240 K, and at cryogenic temperatures, below 160 K, tunneling of deuterium atoms in the metal lattice has been observed. Above 160 K, diffusion occurs by the classical mechanism of overbarrier atomic jumps. Results of quantum diffusion of deuterium in a metal have been obtained for the first time; they used to be known only for the lightest hydrogen isotope, protium, in niobium and tantalum. The analysis has shown that the necessary condition for carrying out the quantum mechanism of deuterium migration is low Debye temperature of a metal, below 200 K. Experimental data on diffusion of hydrogen isotope in an alkali metal have also been obtained for the first time in this paper.

Nuclear reaction analysis online technique has been applied to study the diffusion of deuterium in metals. Investigations ensuring the application of the new method have been performed. These investigations include the development of a device for diffusion annealing of samples in the chamber of an accelerator and an algorithm for taking into account the effect of radiation defects on the diffusion coefficients. Test measurements of the diffusion coefficients of deuterium in nickel in the temperature range from 130 to–60°С have been performed. For negative temperatures, experimental data on the diffusion of a hydrogen isotope in a metal have been obtained for the first time by a direct method and it has been shown that the online nuclear reaction analysis provides reliable data.

The paper proposes and examines an approach to the investigation of the effect of radiation defects on the diffusion coefficients of deuterium in metals with the application of the online nuclear reaction analysis technique (NRAOL).In the development of the method, an assumption was used that the diffusion system is described by two different values of the diffusion coefficients of deuterium, corresponding to the irradiated and unirradiated regions of the sample.The diffusion boundary value problem is formulated and the analytical expression for the calculation of deuterium concentration in the sample is obtained.The simulation calculations are carried out; the depth and time dependences of deuterium concentration in the sample are constructed.A computational algorithm based on the least squares method is developed in order to investigate the effect of radiation defects on the diffusion coefficients of deuterium by NRAOL.Numerical calculations are performed for samples of nickel and sodium by an algorithm-based computer program.