Luminescence characteristics of magnesium aluminate spinel crystals of different stoichiometry

We are grateful to Drs E. Vasil’chenko and A. Maaroos for the help with experiments and useful discussions. This work has been carried out within the framework of the EUROfusion Consortium and has received funding from the Euratom research and training programme 2014-2018 under grant agreement No 633053. The views and opinions expressed herein do not necessarily reflect those of the European Commission. In addition, the research leading to these results has received funding from the Estonian Research Council Institutional Research Funding IUT02-26.Magnesium aluminate spinel single crystals with different stoichiometry, MgAl2O4 (1:1 spinel) and MgO 2.5Al2O3 (1:2.5) were investigated using different optical methods (cathode-, photo- and thermally stimulated luminescence (TSL), optical absorption, "creation spectra" of TSL peaks and phosphorescence by VUV radiation). Low-temperature charge carrier traps and the position of intrinsic UV emission bands depend on the degree of stoichiometry. Antisite defects (ADs), Mg2+ or Al3+ located in a "wrong" cation site (Mg|A1 or Al|Mg) are the main as-grown structural defects, which serve also as efficient traps for electrons and holes as well as seeds for bound excitons. AD concentration is especially high in 1:2.5 spinel. There are several manifestations of ADs (electronic excitations near ADs) in the spectral region of 7-7.5 eV, slightly below the energy gap.Eesti Teadusagentuur IUT02-26; H2020 Euratom 633053; 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

Thermal annealing and transformation of dimer F centers in neutron-irradiated Al2O3 single crystals

This work has been carried out within the framework of the EUROfusion Consortium and has received funding from the Euratom research and training programme 2014-2018 and 2019-2020 under grant agreement No 633053. The views and opinions expressed herein do not necessarily reflect those of the European Commission. In addition, the research leading to these results has received funding from the Estonian Research Council grant (PUT PRG619).The precise study of the thermal annealing of the F2-type dimer defects, being under discussion in the literature for a long time and responsible for the number of absorption bands below 4.5 eV, has been performed in corundum single crystals irradiated by fast neutrons with a fluence of 6.9 × 1018 n/cm2. The Gaussian components of the radiation-induced optical absorption with the maxima at 4.08, 3.45 and 2.75 eV have been considered as a measure of the F2, F2+and F22+centers, respectively. In contrast to the Fand F+ centers, the concentration of which continuously decreases at the sample heating up to 1100 K, the concentration of dimer defects with different charge states passes the increasing stages above 500 K starting from the F22+centers. The tentative mechanisms of such rise of the F22+centers as well as of the subsequent transformation/rise of dimer centers, F22+→F2+→F2at 650-800 K are considered. The possible sources of carriers needed for the recharging of dimer centers are also analysed on the basis of thermally stimulated luminescence measurements up to ~850 K.EUROfusion Consortium, Euratom research and training programme 2014-2018 and 2019-2020, grant agreement No 633053; Estonian Research Council grant (PUT PRG619); 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

Atomic, electronic and magnetic structure of an oxygen interstitial in neutron-irradiated Al2O3 single crystals

This work has been carried out within the framework of the EUROfusion Consortium and has received funding from the Euratom research and training programme 2014-2018 and 2019-2020 under Grant Agreement No. 633053 and Enabling Research project: ENR-MFE19.ISSP-UL-02 “Advanced experimental and theoretical analysis of defect evolution and structural disordering in optical and dielectric materials for fusion application”. The views and opinions expressed herein do not necessarily reflect those of the European Commission. In addition, the research leading to these results has received funding from the Estonian Research Council grant (PUT PRG619).A single radiation-induced superoxide ion O2- has been observed for the first time in metal oxides. This structural defect has been revealed in fast-neutron-irradiated (6.9×1018n/cm2) corundum (α-Al2O3) single crystals using the EPR method. Based on the angular dependence of the EPR lines at the magnetic field rotation in different planes and the determined g tensor components, it is shown that this hole-type O2- center (i) incorporates one regular and one interstitial oxygen atoms being stabilized by a trapped hole (S = 1/2), (ii) occupies one oxygen site in the (0001) plane being oriented along the a axis, and (iii) does not contain any other imperfection/defect in its immediate vicinity. The thermal stepwise annealing (observed via the EPR signal and corresponding optical absorption bands) of the O2- centers, caused by their destruction with release of a mobile ion (tentatively the oxygen ion with the formal charge −1), occurs at 500–750 K, simultaneously with the partial decay of single F-type centers (mostly with the EPR-active F+ centers). The obtained experimental results are in line with the superoxide defect configurations obtained via density functional theory (DFT) calculations employing the hybrid B3PW exchange-correlation functional. In particular, the DFT calculations confirm the O2- center spin S = 1/2, its orientation along the a axis. The O2- center is characterized by a short O–O bond length of 1.34 Å and different atomic charges and magnetic moments of the two oxygens. We emphasize the important role of atomic charges and magnetic moments analysis in order to identify the ground state configuration.Eesti Teadusagentuur PUT PRG619; H2020 Euratom ENR-MFE19,633053; 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

Distinctive features of diffusion-controlled radiation defect recombination in stoichiometric magnesium aluminate spinel single crystals and transparent polycrystalline ceramics

This work has been performed within the framework of the EUROfusion Enabling Research project: ENR-MFE19.ISSP-UL-02 “Advanced experimental and theoretical analysis of defect evolution and structural disordering in optical and dielectric materials for fusion application”. The views and opinions expressed herein do not necessarily reflect those of the European Commission. Research of A.L, E.F.,, V.S and E.S has been partly supported by the Estonian Research Council grant (PUT PRG619); has been also carried out within the framework of the EUROfusion Consortium and has received funding from the Euratom research and training programme 2014–2018 and 2019–2020 under grant agreement No 633053. The views and opinions expressed herein do not necessarily reflect those of the European Commission.MgAl2O4 spinel is important optical material for harsh radiation environment and other important applications. The kinetics of thermal annealing of the basic electron (F, F+) and hole (V) centers in stoichiometric MgAl2O4 spinel irradiated by fast neutrons and protons is analyzed in terms of diffusion-controlled bimolecular reactions. Properties of MgAl2O4 single crystals and optical polycrystalline ceramics are compared. It is demonstrated that both transparent ceramics and single crystals, as well as different types of irradiation show qualitatively similar kinetics, but the effective migration energy Ea and pre-exponent D0 are strongly correlated. Such correlation is discussed in terms of the so-called Meyer-Neldel rule known in chemical kinetics of condensed matter. The results for the irradiated spinel are compared with those for sapphire, MgO and other radiation-resistant materials.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

Accumulation of radiation defects and modification of micromechanical properties under MgO crystal irradiation with swift 132Xe ions

This work has been carried out within the framework of the EUROfusion Consortium and has received funding from the Euratom research and training programme 2014-2018 and 2019-2020 under grant agreement No. 633053. The views and opinions expressed herein do not necessarily reflect those of the European Commission. A.A. also acknowledges support via the project GF AP05134257 of Ministry of Education and Science of the Republic of Kazakhstan .Accumulation of F-type defects under irradiation of MgO crystals by 0.23-GeV 132Xe ions with fluence varying by three orders of magnitude has been investigated via the spectra of optical absorption and low-temperature cathodoluminescence. The number of single centers continuously increases with fluence without any marks of saturation. At the highest fluence, a mean volume concentration of 3.1 × 1019 and 3.35 × 1019 cm−3 is reached for F and F+ centers, respectively. The F+ emission strongly dominates in the cathodoluminescence of irradiated MgO and its enhancement with fluence is detected. However, the creation efficiency of the F2 aggregate centers is very low and fluence dependence has a complicated shape. Radiation-induced changes of micro-mechanical properties of the same samples have been analysed; the depth profiles of hardening correlate with the ion energy loss. A joint contribution of ionization and impact mechanisms in the formation of structural defects under MgO irradiation with Xe ions is considered.H2020 Euratom 2019-2020,633053,2014-2018,GF AP05134257; Ministry of Education and Science of 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

Regional investment policy: Analysis and assessment of the investment environment state

© the authors. The urgency of the problem studied in the paper is conditioned by the fact that stable functioning and development of economic entities, sectors of the economy, regions and the country cannot be carried out without investments. In the modern economy of the Russian Federation, whose conditions of existence can be called non-stationary, one of the problems is attracting investment resources into economic activity and overcoming the conditions for slowing and stopping the growth of the country's economy caused by external unfavorable economic circumstances. In connection with the foregoing, the policy of attracting and managing investments in the regions of the Russian Federation, with a view to ensuring conditions for overcoming the crisis phenomena and resuming the economic growth of the country and its subjects is of particular interest. The intensification of the state investment policy is a core prerequisite for the transition of the economy to sustainable growth. However, in economic market conditions the state is not able to solve this problem to the full. Therefore, the process of activating investment policy at the regional level is becoming topical. The purpose of the paper is to study the management and implementation of investment policy in the region on the example of the Republic of Tatarstan, the analysis and assessment of the investment environment's state. The leading method to research this problem is the statistical one, which is a method of quantitative analysis of a set of homogeneous facts that determine in the aggregate the transition of quantitative changes to qualitative ones. The paper presents the results of assessing the socio-economic development of the region, analyzes the indicators that allow characterizing the investment environment's state. The paper also presents the strategic priorities of the region's investment activities, analyzes the opportunities for their implementation in conditions of non-stationary state, and makes sound conclusions about the need to activate regional investment policies. The materials of the paper are of practical value for specialists dealing with the implementation of the investment policy of the region. © Authors. Terms and conditions of Creative Commons Attribution 4.0 International (CC BY 4.0) apply

The electronic learning system as a means of forming professional competencies among university students

© 2015 by the author(s). The purpose of this article is aimed at the development of pedagogical tools and methods of forming students' competencies in the course of higher education. The submitted paper presents the potential of information technology in forming professional competencies of the university students providing the students' classroom and individual organization. The grounds for the presented paper have become the ideas of competence-based approach, the system of modern didactic principles that intensify the students' learning and cognitive activities. The article describes the structure of modern e-learning system that satisfies the federal state educational standards and contributes to the students' professional competencies. This article is intended for the educators, researchers, heads of educational institutions engaged in the development of academic syllabi and pedagogical tools to provide university students with professional competencies

Formalization of sustainable innovative development process in the model of innovations diffusion

© 2016, Econjournals. All rights reseved. The relevance of the study is reasoned by the fact that the sustainability of innovative development cannot be fully estimated by using the parameters which are traditionally observed by the official statistical bodies, so it suggests the need to improve methodological solutions and technology economic interpretation as well as scaling of indicators’ values in this field. At the macro level there is a small number of indicators on the basis of which we can conclude about the stability of innovative development of economic systems at the meso-and macro level. In this regard, this article aims to formalize the process of sustainable innovation development on the basis of the parameters’ set formation of the innovations’ diffusion model and diagnosis of major economic systems’ development level. The leading method is the parameters’ set formalization of the quantitative model to estimate the level of economic systems’ innovative development based on managerial interpretation of descriptive statistics’ indicators of innovation activity in the framework of economic activities. Aset of quantitative parameters of 9 parametric model of economic systems’ innovative development level is formalized in the article, allowing to diagnose the impact of cyclical factors and the institutional environment that are not fully implemented in the existing macro- systems assessing the level of economic systems’ innovative development; methods of diagnosis and economic interpretation of the relevant indices and indicators’ levels are proposed. The material of this paper is of practical value for enterprises’ innovative activities regulators and monitoring agencies, for regional innovation infrastructure and transfer technology entities, for innovation-active enterprises, because on the basis of the obtained model the optimal solutions in the development of strategies for the upgrading of industries, regions, macro-economic system as a whole are possible

Validation of the model of TSL isothermal decay in dosimetric α-Al 2 O 3 crystals

New features of isothermal build-up of thermally stimulated luminescence (TSL) related to deep traps in anion-deficient alumina single crystals are revealed. It was found that the TSL build-up at 630–750 K depends on the structure of the glow curve and is associated with the presence of a high-temperature component with T m = 700 K. Isothermal TSL build-up for the peak at 573 K is well expressed in UV-irradiated samples and is very weak after sample irradiation by a pulsed electron beam. The TSL build-up for this peak is registered for the luminescence of F centres but is absent for the emission of F 2 2+ centres and chromium ions. The obtained results confirm the validity of the kinetic model of the TSL build-up that takes into account the process of thermal ionization of the excited states of F centres in aluminum oxide. © 2019 Elsevier LtdEesti Teadusagentuur: IUT2-26, PUT PRG111Russian Science Foundation, RSF: 18-72-10082This work was financially supported by the Russian Science Foundation , project No. 18-72-10082 and Estonian Research Council , projects IUT2-26 and PUT PRG111

Formalization of sustainable innovative development process in the model of innovations diffusion

© 2016, Econjournals. All rights reseved.The relevance of the study is reasoned by the fact that the sustainability of innovative development cannot be fully estimated by using the parameters which are traditionally observed by the official statistical bodies, so it suggests the need to improve methodological solutions and technology economic interpretation as well as scaling of indicators’ values in this field. At the macro level there is a small number of indicators on the basis of which we can conclude about the stability of innovative development of economic systems at the meso-and macro level. In this regard, this article aims to formalize the process of sustainable innovation development on the basis of the parameters’ set formation of the innovations’ diffusion model and diagnosis of major economic systems’ development level. The leading method is the parameters’ set formalization of the quantitative model to estimate the level of economic systems’ innovative development based on managerial interpretation of descriptive statistics’ indicators of innovation activity in the framework of economic activities. Aset of quantitative parameters of 9 parametric model of economic systems’ innovative development level is formalized in the article, allowing to diagnose the impact of cyclical factors and the institutional environment that are not fully implemented in the existing macro- systems assessing the level of economic systems’ innovative development; methods of diagnosis and economic interpretation of the relevant indices and indicators’ levels are proposed. The material of this paper is of practical value for enterprises’ innovative activities regulators and monitoring agencies, for regional innovation infrastructure and transfer technology entities, for innovation-active enterprises, because on the basis of the obtained model the optimal solutions in the development of strategies for the upgrading of industries, regions, macro-economic system as a whole are possible