Depth profiles of aggregate centers and nanodefects in LiF crystals irradiated with 34 MeV 84Kr, 56 MeV 40Ar and 12 MeV 12C ions

I. Manika, J. Maniks and R. Zabels acknowledge the national project IMIS2. A. Dauletbekova, A. Akilbekov, M. Zdorovets and A. Seitbayev acknowledge the GF AP05134257of Ministry of Education and Science the Republic of Kazakhstan.Depth profiles of nanohardness and photoluminescence of F2 and F3 + centers in LiF crystals irradiated with 12 MeV 12C, 56 MeV 40Ar and 34 MeV 84Kr ions at fluences 1010–1015 ions/cm2 have been studied using laser scanning confocal microscopy, dislocation etching and nanoindentation techniques. The room temperature irradiation experiments were performed at DC-60 cyclotron (Astana, Kazakhstan). It was found that the luminescence intensity profiles of aggregate color centers at low ion fluences correlate with electronic stopping profiles. The maximum intensity of aggregate center luminescence is observed at fluence around 1013 ions/cm2 and rapidly decreases with further increase of fluence. At the highest ion fluences, the luminescence signal is registered in the end-of-range area only. The depth profiles of nanohardness and chemical etching have shown remarkable ion-induced formation of dislocations and increase of hardness which in the major part of the ion range correlate with the depth profile of electronic energy loss. An exception is the end-of-range region where strong contribution of nuclear energy loss to hardening at high fluences is observed.IMIS2; Ministry of Education and Science the Republic of Kazakhstan GF AP05134257; Institute of Solid State Physics, University of Latvia as the Center of Excellence has received funding from the European Union’s Horizon 2020 Framework Programme H2020-WIDESPREAD-01-2016-2017-TeamingPhase2 under grant agreement No. 739508, project CAMART

Study of the Structural, Optical and Strength Properties of Glass-like (1−x)ZnO–0.25Al₂O₃–0.25WO₃–xBi₂O₃ Ceramics

The main purpose of this work is to study the effect of substitution of zinc oxide for bismuth oxide in the composition of (1−x)ZnO–0.25Al2O3–0.25WO3–xBi2O3 ceramics, as well as the accompanying processes of phase transformations and their influence on the optical and strength properties of ceramics. The use of these oxide compounds as materials for creating shielding coatings or ceramics is due to the combination of their structural, optical, and strength properties, which make it possible to compete with traditional protective glasses based on rare earth oxide compounds. Interest in these types of ceramics is due to their potential for use as basic materials for shielding ionizing radiation as well as for use as radiation-resistant coatings. The main research methods were X-ray diffractometry to determine the phase composition of ceramics; scanning electron microscopy and energy dispersive analysis to determine the morphological features and isotropy of the distribution of elements in the structure; and UV-V is spectroscopy to determine the optical properties of ceramics. During the studies, it was found that an increase in the Bi2O3 concentration leads to the formation of new phase inclusions in the form of orthorhombic Bi2WO6 and Bi2W2O9 phases, the appearance of which leads to an increase in the density of ceramics and a change in the dislocation density. An analysis of the strength properties, in particular, hardness and crack resistance, showed that a change in the phase composition of ceramics with an increase in the Bi2O3 concentration leads to a significant strengthening of the ceramics, which is due to the effect of the presence of interfacial boundaries as well as an increase in the dislocation density

Study of the Phase Formation Processes and Their Influence on the Change in the Optical and Shielding Characteristics of 0.25ZnO–0.25Al₂O₃–0.25WO₃–0.25Bi₂O₃ Ceramics

The phase formation processes in 0.25ZnO–0.25Al2O3–0.25WO3–0.25Bi2O3 ceramics with variation in the thermal annealing temperature were evaluated in this study. According to the obtained data on the phase composition dependent on the annealing temperature, the phase transformation dynamics, which can be written in the form of ZnO/Bi2O3/WO3/Al2O3 → ZnBi38O60/ZnO/Bi2WO6/WO3 → Bi2Al4O9/ZnBi38O60/Bi2WO6/ZnO/WO3 → ZnWO4/Bi2WO6/ZnAl2O4/ZnO → ZnWO4/Bi2WO6/ZnAl2O4 → Bi2WO6/ZnWO4/ZnAl2O4 → ZnAl2O4/Bi2WO6/Bi2W2O9, were established. It has been found that the formation of phases of complex oxides of the ZnWO4, Bi2WO6 and Bi2W2O9 types in the composition of ceramics leads to an increase in the density of ceramics up to 8.05–8.10 g/cm3, which positively affects the shielding efficiency and strength characteristics. According to the data on the change in strength characteristics, it was found that a change in the density of ceramics from 6.3 to 8.05–8.10 g/cm3 leads to strengthening and an increase in the crack resistance of ceramics by 75–80%, which indicates a high strength of ceramics and their increased resistance to external influences. As shown by the evaluation of the shielding characteristics, an increase in the density of ceramics due to a phase composition change leads to an increase in the shielding efficiency and a decrease in gamma intensity by a factor of 3–3.5. At the same time, on the base of the data presented, it can be concluded that ceramics obtained in the range of 900–1100 °C have both high shielding characteristics and high strength and resistance to external influences