Институту общей и неорганической химии Национальной академии наук Беларуси – 60 лет

The historical review of the Institute of General and Inorganic Chemistry of the National Academy of Sciences of Belarus considers all periods of the Institute’s evolution, starting with its organization in 1959, forming the main structural divisions and areas of research and development (1959–1968), structuring these areas and accelerating their development (1969–1990), optimization and headway with a primary focus on the scientific support of important tasks of industry and the agricultural complex of the Republic of Belarus (1991–2019). The information on the formation and development of scientific schools at the Institute, their outstanding achievements and examples of successful implementation of developments in enterprises and organizations of the national economic complex is presented. In chronological order, the results of the activities of the Institute scientists structured by the main scientific areas are reviewed, and references to their published books and monographs are given.В историческом обзоре деятельности Института общей и неорганической химии НАН Беларуси рассматриваются все этапы развития Института, начиная с его организации в 1959 году, формирования основных структурных подразделений и направлений научных исследований и разработок (1959–1968 гг.), структурирования этих направлений и их ускоренного развития (1969–1990 гг.), оптимизации и поступательного движения с преимущественной ориентацией на научное обеспечение важных задач отраслей промышленности и сельскохозяйственного комплекса Республики Беларусь (1991–2019 гг.). Представлена информация о формировании и развитии научных школ в Институте, об их наиболее ярких достижениях и примерах успешного внедрения разработок на предприятиях и организациях народнохозяйственного комплекса страны. В хронологической последовательности рассматриваются структурированные по основным научным направлениям результаты деятельности сотрудников Института, даются ссылки на опубликованные ими книги и монографии

Формирование системы двойных связей в процессе термокаталитической дегидратации поливинилового спирта

The formation of a conjugated bond system in the heat treatment of polyvinyl alcohol films with the addition of hydrochloric acid as an acid catalyst for thermal dehydration in the range of 80-150 °C has been studied on the base of electronic spectra. It is established that the fine structure in the absorption spectra in the 282-443 nm region is associated with electronic transitions in polyconjugated chains with the number of carbon atoms from 8 to 18, with the exception of the bands at 310 and 342 nm; only one peak at 361 nm of four lines in the wide band at 352-380 nm is associated with optical transitions in the polyconjugated chain containing 12 carbon atoms. It is shown that the long-wave boundary of the spectrum is due to electronic transitions in polyconjugated chains of the largest sizes; the maximum size of such chains can be determined by comparing the dependence of the Tauc band gap and the energy of the optical transitions as an inverse function of the number of carbon atoms in the conjugate chain. Since the typical sizes of such poly-conjugation chains are hundreds of carbon atoms (about 300 atoms in films heated at 100 °C), these chains can be considered as trans-polyacetylene nanoclusters incorporated into a polyvinyl alcohol matrix.На основании электронных спектров поглощения изучено формирование системы сопряженных связей при термообработке пленок поливинилового спирта в интервале 80-150 °С с добавкой хлористоводородной кислоты в качестве кислотного катализатора термической дегидратации. Установлено, что тонкая структура в спектрах поглощения в области 282-443 нм связана с электронными переходами в цепях полисопряжения с количеством атомов углерода от 8 до 18, за исключением полос при 310 и 342 нм и трех линий в составе широкой полосы при 352-380 нм, содержащее также пик при 361 нм, обусловленный переходами в цепи полисопряжения из 12 атомов углерода. Показано, что длинноволновая граница спектра обусловлена электронными переходами в цепях полисопряжения наибольших размеров; максимальный размер таких цепей можно определить из сопоставления зависимости ширины запрещенной зоны Тауца и энергии оптических переходов как обратной функции количества атомов углерода в цепи сопряжения. Поскольку типичные размеры таких цепей полисопряжения составляют сотни атомов углерода (около 300 атомов в пленках, прогретых при 100 °С), их можно рассматривать как нанокластеры трансполиацетилена, инкорпорированные в матрицу поливинилового спирта

ОПРЕДЕЛЕНИЕ АЛЮМИНИЯ В ВОДНЫХ РАСТВОРАХ МЕТОДОМ ИНВЕРСИОННОЙ ВОЛЬТАМПЕРОМЕТРИИ

The possibility for determining the concentration of aluminum in aqueous solutions by stripping voltammetry has been demonstrated. The method is based on electrochemical cathodic aluminum accumulation on a vibrating mercury film electrode with subsequent registration of anodic current on the potentiodynamic voltammogram. Unlike conventional electrochemical methods of indirect determination of aluminum, based on the analysis of the adsorbed complexes of aluminum with dyes, the proposed approach allows to realize the direct determination of aluminum without binding it into coordination compounds. The method is based on the process of reversible reduction and oxidation of aluminum at pH 3,0-4,5 in aqueous dimethyl sulfoxide electrolyte containing calcium chloride, discovered by the authors, and has relative standard deviation of 1,8-2,4% in the aluminum concentration range from 10-4 to 10-5 g/dm3.Показана возможность определения концентрации алюминия в водных растворах методом инверсионной вольт-амперометрии. Метод основан на электрохимическом катодном концентрировании алюминия на вибрирующем ртутном пленочном электроде с последующей регистрацией анодного тока на потенциодинамической вольтампе-рограмме. В отличие от известных электрохимических методик косвенного определения алюминия, основанных на анализе адсорбированных комплексов алюминия с красителями, предложенный подход позволяет осуществлять прямое определение алюминия без связывания его в комплексные соединения. Метод базируется на обнаруженном авторами обратимом процессе восстановления-окисления алюминия при рН 3,0-4,5 в водно-диметилсульфоксидном электролите, содержащем хлорид кальция, и характеризуется относительным стандартным отклонением 1,8-2,4 % в интервале концентраций алюминия от 10-4 до 10-5 г/дм3

Influence of wide band gap oxide substrates on the photoelectrochemical properties and structural disorder of CdS nanoparticles grown by the successive ionic layer adsorption and reaction (SILAR) method

The photoelectrochemical properties of nanoheterostructures based on the wide band gap oxide substrates (ZnO, TiO2, In2O3) and CdS nanoparticles deposited by the successive ionic layer adsorption and reaction (SILAR) method have been studied as a function of the CdS deposition cycle number (N). The incident photon-to-current conversion efficiency (IPCE) passes through a maximum with the increase of N, which is ascribed to the competition between the increase in optical absorption and photocarrier recombination. The maximal IPCE values for the In2O3/CdS and ZnO/CdS heterostructures are attained at N ≈ 20, whereas for TiO2/CdS, the appropriate N value is an order of magnitude higher. The photocurrent and Raman spectroscopy studies of CdS nanoparticles revealed the occurrence of the quantum confinement effect, demonstrating the most rapid weakening with the increase of N in ZnO/CdS heterostructures. The structural disorder of CdS nanoparticles was characterized by the Urbach energy (EU), spectral width of the CdS longitudinal optical (LO) phonon band and the relative intensity of the surface optical (SO) phonon band in the Raman spectra. Maximal values of EU (100–120 meV) correspond to СdS nanoparticles on a In2O3 surface, correlating with the fact that the CdS LO band spectral width and intensity ratio for the CdS SO and LO bands are maximal for In2O3/CdS films. A notable variation in the degree of disorder of CdS nanoparticles is observed only in the initial stages of CdS growth (several tens of deposition cycles), indicating the preservation of the nanocrystalline state of CdS over a wide range of SILAR cycles

Generation IV nuclear energy system initiative. Large GFR core subassemblydesign for the Gas-Cooled Fast Reactor.

Gas-cooled fast reactor (GFR) designs are being developed to meet Gen IV goals of sustainability, economics, safety and reliability, and proliferation resistance and physical protection as part of an International Generation IV Nuclear Energy System Research Initiative effort. Different organizations are involved in the development of a variety of GFR design concepts. The current analysis has focused on the evaluation of low-pressure drop, pin-core designs with favorable passive cooling properties. Initial evaluation of the passive cooling safety case for the GFR during depressurized decay heat removal accidents with concurrent loss of electric power have resulted in requirements for a reduction of core power density to the 100 w/cc level and a low core pressure drop of 0.5 bars. Additional design constraints and the implementation of their constraints are evaluated in this study to enhance and passive cooling properties of the reactor. Passive cooling is made easier by a flat radial distribution of the decay heat. One goal of this study was to evaluate the radial power distribution and determine to what extent it can be flattened, since the decay heat is nearly proportional to the fission power at shutdown. In line with this investigation of the radial power profile, an assessment was also made of the control rod configuration. The layout provided a large number of control rod locations with a fixed area provided for control rods. The number of control rods was consistent with other fast reactor designs. The adequacy of the available control rod locations was evaluated. Future studies will be needed to optimize the control rod designs and evaluate the shutdown system. The case for low pressure drop core can be improved by the minimization of pressure drop sources such as the number of required fuel spacers in the subassembly design and by the details of the fuel pin design. The fuel pin design is determined by a number of neutronic, thermal-hydraulic (gas dynamics) and fuel performance considerations. For the purposes of this study, the starting point is the fuel pin design established by the CEA-ANL/US I-NERI collaboration project for the selected 2400 MWt large rector option. Structural mechanics factors are now included in the design assessment. In particular, thermal bowing establishes a bound on the minimum of fuel pin spacers required in each fuel subassembly to prevent the local flow channel restrictions and pin-to-pin mechanical interaction. There are also fabrication limitations on the maximum length of SiC fuel pin cladding which can be manufactured. This geometric limitation effects the minimum ceramic clad thickness which can be produced. This ties into the fuel pin heat transfer and temperature thresholds. All these additional design factors were included in the current iteration on the subassembly design to produce a lower core pressure drop. A more detailed definition of the fuel pin/subassembly design is proposed here to meet these limitations. This subassembly design was then evaluated under low pressure natural convection conditions to assess its acceptability for the decay heat removal accidents. A number of integrated decay heat removal (DHR) loop plus core calculations were performed to scope the thermal-hydraulic response of the subassembly design to the accidents of interest. It is evident that there is a large sensitivity to the guard containment back pressure for these designs. The implication of this conclusion and possible design modifications to reduce this sensitivity will be explored under the auspices of the International GENIV GFR collaborative R&D plan. Chapter 2 describes the core reference design for the 2,400 MWt GFR being evaluated. The methodology, modeling, and codes used in the analysis of the fuel pin structural behavior are described in Chapter 3. Chapter 4 provides the result of the thermal-hydraulic study of the assembly design for the accidents of interest. An evaluation of the performance and control rod reactivity control is also presented in Chapter 2