Influence of oxygen fraction on the characteristics of titanium oxide coatings obtained by the magnetron method

Titanium oxide coatings were obtained by magnetron sputtering on a glass substrate with different oxygen fraction in the plasma. Studies were carried out by scanning electron microscopy of the obtained coating samples establishing the role of oxygen in the process of crystallization of TiOx-coatings. It was found that with increasing the oxygen fraction in the vacuum arc discharge plasma the crystal grain size increases, the time of coating on the substrate increases, and the crystal layer has a columnar structure. The presence of amorphous and crystalline phase for all coating samples was revealed, with the predominance of the former. On the surface microphotographs of the coatings microcraters were found, on the surface of the samples obtained at the concentration of O2 in the plasma 14% of their concentration is maximum, this can be explained by changes in the state of the plasma, starting to occur at this concentration of reaction gas. Vacuum photonic annealing of the obtained coatings was performed. Vacuum radiation annealing in the furnace led to modification of coatings: sintering of coatings, increase of their crystallinity. An increase in crystallite size in a sample with an oxygen fraction of 12% was detected.

ANALYSIS OF STRUCTURAL TRANSFORMATIONS IN NATURAL QUARTZITES UNDER THE INFLUENCE OF GAMMA IRRADIATION

Using the methods of IR spectroscopy, crystal-optical and XRD analysis the evolution of the structure of Ovruch deposit natural quartzites under the influence of γ-irradiation in the range of absorbed doses (Dabs =106…3.5107 Gy) has been researched. The elemental composition of natural quartzites was determined by the gamma activation method on a linear electron accelerator. It was found that as a result of irradiation the crystal structure of quartz, which forms the basis of quartzite, is improved due to radiation annealing of the defects in the initial structure. At the same time crystallization of amorphous silica, which fringes large grains of quartz, occurs with its transformation into fine-crystalline quartz. These processes do not lead to cracking in the quartzite rock. Obtained data indicates a high radiation resistance of the Ovruch deposit quartzites and confirms the prospects of using this geological formation as a natural barrier for the construction of radioactive waste long-term storage.

THE EFFECT OF THE EXTERNAL MEDIUM ON THE STRUCTURAL-PHASE TRANSFORMATIONS OF QUARTZITE UPON HIGH-ENERGY ELECTRON IRRADIATION

The structural transformations of the natural quartzite under the electron irradiation in doses range of 107…108 Gy in various medium were studied using IR-spectroscopy, X-ray diffraction, and crystal-optical analyzes. It was established that under the irradiation, both in air and in a water stream, intense crystallization of the amorphous component occurs, which is siliceous cement. The initial crystal structure of quartzite is also improved as a result of radiation annealing of defects and impurities present in the initial quartz. It was found that the water medium significantly accelerates these processes, however, in the studied doses range for both types of irradiation, degradation of the quartzite crystal structure is not observed.

Erratum - In the article "Rapid and long-term gamma-radiation annealing in low-dropout voltage regulators" by Vladimir Dj. Vukic

Published in the Nuclear Technology & Radiation Protection journal, 32 (2017), 2, pp. 155-165, during the technical preparation of the article, errors in equations (1) and (3) and in the accompanying texts were made. <br><br><font color="red"><b> Link to the corrected article <u><a href="http://dx.doi.org/10.2298/NTRP1702155V">10.2298/NTRP1702155V</a></b></u>

Rapid and long-term gamma-radiation annealing in low-dropout voltage regulators

Samples of four types of low-dropout voltage regulators, with both serial pnp and npn transistors, were examined in room-temperature isothermal gamma radiation annealing. After uninterrupted exposure to a total ionising dose of 500 Gy, biased and loaded voltage regulators were examined in room-temperature annealing within the first 30 minutes after the exposure. Beside the on-line measurement of output voltage and quiescent current during the thirty-minute period immediately after irradiation, also results were procured after 10-year room-temperature spontaneous recovery. Data obtained during the irradiation and rapid annealing were fitted with linear, exponential, and power-law regression functions. A simple procedure was proposed, based on the quiescent current annealing factor, for the quick estimation of the integrated voltage regulator's radiation sensitivity during the post-irradiation isothermal annealing. In order to estimate the circuit's radiation sensitivity, immediately after irradiation, tested devices have to be left in the same operating conditions as during the exposure. If a clear trend of the quiescent current recovery can be observed, further examinations have to be implemented to estimate if a circuit is acceptably radiation-tolerant. If no recovery trend can be observed within the first hour after irradiation, or even further degradation is noticed, then the examined voltage regulator is a radiation-sensitive device and cannot be used in radiation environments. The described procedure is based on the macroscopic effects of the radiation-induced charge-trapping in field oxides and interfaces. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. 171007: Physical and functional effects of the interaction of radiation with electrical and biological systems] <br><br><font color="red"><b> This article has been corrected. Link to the correction <u><a href="http://dx.doi.org/10.2298/NTRP1703305E">10.2298/NTRP1703305E</a><u></b></font>

Laser Annealing of 8YSZ Powders

In the article are presented investigations of the reflectance and the absorption coefficient of yttrium partially stabilized zirconia (YPSZ), for 10,6μm wavelength electromagnetic radiation as well as for the wavelengths in the range of 0,5-1,1μm. Based on an experimentally obtained absorption coefficients, the amount of laser power densities absorbed within YPSZ was calculated. Also, experimental investigations with Disk laser and CO2 laser radiation annealing were conducted. It was shown that for different lasers wavelengths and for the same laser beam intensities the microstructural changes in YPSZ are different.