Features of the Phase Composition and Structure of Eu Doped Y2O3 Submicrospheres

Polycrystalline, non-agglomerated nanopowders based on monosized (Y1-xEux)2O3 submicrospheres were prepared. It was shown that the annealing temperature strongly influences on the structure, mor-phology and composition of the spherical (Y1-xEux)2O3 phosphors obtained. It was found that the concentra-tion quenching effects of Eu3+ luminescence in the (Y1-xEux)2O3 spheres with 70-280 nm diameter is shifted to lower Eu3+ concentrations (x =0,02; 0,05 for 70 and 280 nm spheres respectively) compared with the mi-crocrystalline powders with similar composition (x = 0,09). The reason of this phenomenon probably is for-mation of inhomogeneous phase of (Y1-xEux)2O3 solid solution in the nanopowders with the primary location of bigger Eu3+ ions in the surface area due to active diffusion processes. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3521

Interregional Inequality of Population Incomes: Problems of Methodology and Estimation in the Russian Federation

Currently, the priority of the Russian Federation socio-economic development is to achieve sustainable economic growth. A significant obstacle to the achievement of this goal is the unevenness and disproportionality in the socio-economic development of the Russian regions. This circumstance makes the problem of an objective and adequate assessment of Russian regions the interregional differentiation particularly relevant. The study notes that the nominal monetary income of the population does not take into account regional differences in price level. This work discusses methodological approaches of reliable determination, advantages of weighted and unweighted estimates in the interregional inequality, special attention is paid to weighing the average per capita indicators of the subject of the Russia for the proportion of the region’s population in the country’s population. To assess the purchasing power of the population at the regional level, the authors propose to use a modified cost of living index. As a result of the study, the dynamics of the variation coefficient of the average per capita monetary incomes of the population and adjusted for the modified cost-of-living index were determined, on the basis of which the regions of Russia were divided into three groups. The efficiency of the transition to the analysis of incomes comparable in purchasing power, as comparison of weighted and unweighted variation coefficients, has been proved. The trend towards smoothing interregional inequality, which is caused by the accelerated growth of real incomes of the population in the low-income group of Russian regions

Borate single crystals for polyfunctional applications: production and properties

Literature data and results of authors' studies are rewieved concerning structure, growing conditions, non-linear optical, piezoelectric and spectral characteristics of borate single crystals Li₂B₄O₇, LiB₃O₅, b-BaB₂O₄, LaB₃O₆, Li₆Gd(BO₃)₃. A high scintillation efficiency of LaB₃O₆ and Li₆Gd(BO₃)₃:Ce single crystals as well as the high thermostimulated luminescence yield of Li₂B₄O₇: (Ce, Eu, Tm) ones have been demonstrated

Growing of Sm³⁺ doped polycrystalline calcium fluorapatite from aqueous solutions

Polycrystalline samples of Са₁₀(РО₄)₆F₂ (calcium fluor-apatite, FAP) and of Sm³⁺ doped FAP have been obtained by precipitation from aqueous solutions. The optimum conditions to obtain single-phase polycrystalline doped and undoped FAP are pН = 4.7 and Т = 80℃. Effect of physicochemical conditions on the sample characteristics has been studied. The luminescence and luminescence excitation spectra of FAP doped with samarium have been measured. The spectra obtained are identified as those of Sm³⁺.Методом осаждения из водных растворов получены поликристаллические образцы Са₁₀(РО₄)₆F₂ (фторапатита кальция, ФАП) и ФАП, активированного Sm³⁺. Оптимальными условиями получения монофазного, поликристаллического, допированного и не допированного ФАП являются pН = 4.7 и Т = 80℃. Изучено влияние физико-химических условий на характеристики образующихся осадков. Измерены спектры люминесценции и её возбуждения для образцов ФАП, допированных ионами самария. Полученный спектр люминесценции, идентифицируется как спектр люминесценции Sm³⁺.Використовуючи метод осадження з водних розчинiв отримано полiкристалiчнi зразки Са₁₀(РО₄)₆F₂ (фторапатиту кальцiю, ФАП) i ФАП, активованого Sm³⁺. Оптимальними умовами отримання монофазного полiкристалiчного допованого та недопованого ФАП є: pН = 4.7 i Т = 80℃. Вивчено вплив фiзико-хiмiчних умов на характеристики отриманних осадiв. Отримано спектри люмiнесценцiї та її збудження для зразкiв ФАП та ФАП, активованного iонами самарiю. Отриманий спектр люмiнесценцiї iдентифiкується як спектр люминесценцiї Sm³⁺

Model of socio-economic factors in the spread of SARS-CoV-2 across Russian regions

The worldwide spread of a new infection SARS-CoV-2 makes relevant the analysis of the different factors that lead to the vulnerability of modern civilization to previously unknown diseases. In this regard, the development of mathematical models describing the evolution of epidemics like COVID-19 and the identification of socio-economic factors affecting the epidemiological situation in regions is an important research task. The paper proposes a probabilistic mathematical model for the spread of the COVID-19 epidemic, which allows to analyze the evolution of the main characteristics of the disease and to assess main factors influencing them. The study is based on the official statistical data on the spread of the COVID 19 presented on coronavirus sites in the Russian Federation and other countries, the Yandex Data Lens dataset service, as well as the data from the Federal State Statistics Service. In the research some data mining methods were used for evaluation the model’s parameters. The model equations allow to predict the evolution of the disease and estimate the confidence interval of such prognosis. We estimated the ratio of detected and hidden cases of the disease, the distribution of the disease’s duration probability and its average value for different regions. It has been mathematically proven that the vaccination is the necessary and sufficient condition of achievement a stationary stable state - the cessation of a pandemic. The regions of Russian Federation were clustered by the course of the disease COVID-19 on the base of k-means method. The analysis of the most important socio-economic factors affecting the epidemiological situation was provided separately for each cluster

Optical properties of CdS and PbS nanocrystals adsorbed on silica nanoparticles

The adsorption mechanism of CdS and PbS semiconductor nanocrystals on the surface of spherical silica particles has been investigated. The presence of quantum size effects in the "core-shell" heteronanostructures with dielectric SiO₂ core and semiconductor shell consisting of nanocrystals has been established. Influence of the core size and a degree of its covering with CdS, PbS nanocrystals on optical properties of heteronanostructures has been shown

Synthesis of strontium tetroborate SrB₄O₇ for single crystal growth

The possiblility of the single phase SrB₄O₇ synthesis the amorphous phase formation stage has been shown. Using XPA and DTA methods, the formation of strontium borate hydrates has been determined to occur at T = 95±5°C in the course of strontium carbonate interaction with boric acid. The dehydration of strontium borate crystal hydrates results in amorphous phase formation. A further phase transition (borate rearrangement) of this phase at T = 750°C results in formation of polycrystalline SrB₄O₇

Nanosized phosphors based on Gd₁₋ₓEuₓPO₄ obtained by low-temperature methods

Nanowires (10 to 50 nm wide, up to 2 μm long) and nanoplates (60 to 100 nm wide, 70 to 500 nm long) of europium doped gadolinium orthophosphate with narrow size distribution have been obtained by precipitation from aqueous solution using microemulsion and ultrasound treatment. The crystal structure of all nanosized samples belong to monazite structure. The size and shape of the objects has been shown to influence the luminescence spectra of activator. It is concluded that, the concentration of europium ion localization sites in low symmetry position with respect to the central ions increases in nanosized matrices as compared to GdPO₄:Eu³⁺ polycrystals.Нанонитки (товщиною 10-50 нм та довжиною до 2 мкм) та нанопластинки (товщиною 60-100 нм та довжиною 70-500 нм) ортофосфату гадолінію, активованого іонами європію, з вузьким розподілом частинок за розміром отримані методами осадження з водних розчинів з використанням мікроемульсій та ультразвукової обробки. Кристалічна гратка усіх нанорозмірних зразків належить до структури монациту. Показано, що розмір та форма об'єктів впливають на спектри люмінесценції активатора. Зроблено висновок, що у порівнянні зі звичайними полікристалами GdPO₄:Eu³⁺, у нанорозмірних матрицях концентрація місць локалізації іонів європію у низькосиметричному положенні відносно заміщеного іона зростає.Нанонити (толщиной 10-50 нм и длиной до 2 мкм) и нанопластины (толщиной 60-100 нм и длиной 70-500 нм) ортофосфата гадолиния, активированного ионами европия, с узким распределением частиц по размеру получены методами осаждения из водных растворов с использованием микроэмульсий и обработки ультразвуком. Кристаллическая решетка всех наноразмерных образцов принадлежит структуре монацита. Показано, что размер и форма объектов влияют на спектры люминесценции активатора. Сделан вывод, что по сравнению с обычными поликристаллами GdPO₄:Eu³⁺, в наноразмерных матрицах концентрация мест локализации ионов европия в низкосимметричном положении относительно центрального иона возрастает