The results of studying high-temperature oxygen desorption from an YBaCo2O6-delta oxide in the quasi-equilibrium regime are presented. The solid-phase synthesis of the oxide, ways and methods of its characterisation are described. The data obtained by quasi-equilibrium oxygen release technique allowed us to provide a reliable description of oxygen desorption from the oxide and to calculate the change in oxygen content in the oxide. Oxygen content in YBaCo2O6-delta is determined as a continuous function of temperature and the partial pressure of oxygen within the ranges of 600-900 degrees C and 0.2-10(-5) atm, respectively. The data obtained make it possible to identify the conditions of phase transitions in the oxide and determine the stability regions of the conductive phase, which is necessary for the development of cathode materials for solid oxide fuel cells.

Разработана математическая модель потока водорода из газовых смесей через стенки капиллярных трубок из металлического никеля, учитывающая неоднородность парциального давления водорода вдоль длинной трубки, а также неоднородность температуры на разных участках трубки. С помощью модели на основе экспериментальных данных рассчитаны кинетические параметры транспорта водорода в диапазоне температур 600–850 °C и диапазоне парциальных давлений водорода 0.1–1.0 атм. Модель может быть использована при проектировании мембранных модулей сепарации водорода из газовых смесей для расчета длины единичных мембран, их количества и оптимальной скорости потока водородсодержащей смеси через мембрану. A mathematical model of the flow of hydrogen from gas mixtures through the walls of capillary tubes made of metallic nickel has been developed, taking into account the inhomogeneity of the partial pressure of hydrogen along a long tube, as well as temperature nonuniformity in different regions of the tube. Using the model and relying on experimental data, the kinetic parameters of hydrogen transport were calculated within the temperature range of 600–850 ºС and the hydrogen partial pressure range of 0.3–0.8 atm. The model can be used in the design of membrane modules for hydrogen separation from gas mixtures to calculate the length of individual membranes, their number, and the optimal flow rate of the hydrogen-containing gas mixture through the membrane.

Perovskite-like oxides based on lanthanum–strontium ferrites are considered to be promising electrode materials for use in various types of fuel cells, and the strategy of modifying these materials by partial substitution of iron with highly charged ferroactive cations has proved to be an efficient way to increase their chemical stability. In this work, the results of a study of the permeability of microtubular oxygen membranes based on La0.5Sr0.5Fe1 – xNbxO3 – δ are presented for the first time. The activation energy of oxide bulk diffusion was found (20 ± 4 kJ/mol).

A mathematical model of the flow of hydrogen from gas mixtures through the walls of capillary tubes made of metallic nickel has been developed, taking into account the inhomogeneity of the partial pressure of hydrogen along a long tube, as well as temperature nonuniformity in different regions of the tube. Using the model and relying on experimental data, the kinetic parameters of hydrogen transport were calculated within the temperature range of 600-850 °С and the hydrogen partial pressure range of 0.3-0.8 atm. The model can be used in the design of membrane modules for hydrogen separation from gas mixtures to calculate the length of individual membranes, their number, and the optimal flow rate of the hydrogen-containing gas mixture through the membrane.

The search for new solid ionic conductors is an important topic of material science that requires significant resources, but can be accelerated using machine learning (ML) techniques. In this work, ML methods were applied to predict the migration energy of working ions. The training set is based on data on 225 lithium ion migration channels in 23 ion conductors. The descriptors were the parameters of free space in the crystal obtained by the Voronoi partitioning method. The accuracy of migration energy prediction was evaluated by comparison with the data obtained by the density functional theory method. Two methods of ML were applied in the work: support vector regression and ordinal regression. It is shown that the parameters of free space in a crystal correlate with the migration energy, while the best results are obtained by ordinal regression. The developed ML models can be used as an additional filter in the analysis of ionic conductivity in solids.

Федеральное государственное бюджетное учреждение наукиИнститут неорганической химии им.А. В. Николаева Сибирского отделения Российской академии наук

Методом РСА изучено строение биядерного тиоцианатного комплекса ниобия(IV) — (Bu4N)4[Nb2(μ2-S2)2(NCS)8]·H2O (1·H2O). Соединение 1·H2O кристаллизуется в ромбической сингонии (пространственная группа Pbca) с параметрами элементарной ячейки a = 23.2139(4) Å, b = 25.2962(4) Å, с = 32.5478(6) Å, V = 19112.8(6) Å3, R = 0.0592. Методами рентгеновской спектроскопии изучена электронная структура комплексов (Bu4N)4[Nb2(μ2-S2)2(NCS)8] и (Bu4N)4[Nb2(μ2-Se2)2(NCS)8], проведено сравнение с полимерными халькогалогенидами Nb2S4Br4 и Nb2Se4Br4. Методом РФЭС показано, что эффективные заряды на атомах ядра {Nb2(μ-Q2)2}4+ (Q = S, Se) не изменяются при переходе от Br– к NCS– лигандам. Методами РЭС и XANES изучена структура HOMO и LUMO для (Bu4N)4[Nb2(μ2-S2)2(NCS)8] и (Bu4N)4[Nb2(μ2-Se2)2(NCS)8]. Установлено, что наибольшие вклады состояний S 3p лигандов NCS– в занятые молекулярные орбитали находятся вблизи верхней границы валентной зоны, тогда как вклады от дихалькогенидных мостиковых лигандов имеют более равномерное распределение. В случае зоны проводимости вклады состояний S 3p лигандов NCS– расположены в более глубокой области, а вклады от дихалькогенидных мостиковых лигандов — вблизи нижней границы зоны проводимости. Взаимодействие состояний Nb 4d и S 3p/Se 4p дихалькогенидных мостиков для HOMO имеет разрыхляющий характер, для всех остальных занятых молекулярных орбиталей — связующий, а для всех свободных молекулярных орбиталей — разрыхляющий.

The structure of a binuclear niobium(IV) thiocyanate complex (Bu 4 N) 4 [Nb 2 (μ 2 -S 2 ) 2 (NCS) 8 ]·H 2 O ( 1 ·H 2 O) is studied by X-ray crystallography. Compound 1 ·H 2 O crystallizes in the orthorhombic crystal system (space group Pbca ) with unit cell parameters a = 23.2139(4) Å, b = 25.2962(4) Å, с = 32.5478(6) Å, V = 19112.8(6) Å 3 , R = 0.0592. The electronic structures of (Bu 4 N) 4 [Nb 2 (μ 2 -S 2 ) 2 (NCS) 8 ] and (Bu 4 N) 4 [Nb 2 (μ 2 -Se 2 ) 2 (NCS) 8 ] complexes are investigated by X-ray spectroscopy techniques and compared with the structures of polymeric chalcogenides Nb 2 S 4 Br 4 and Nb 2 Se 4 Br 4 . By XPS it is shown that effective charges on atoms of the {Nb 2 (μ- Q 2 ) 2 } 4+ ( Q = S, Se) core do not change when passing from Br – to NCS – ligands. The HOMO and LUMO structures of (Bu 4 N) 4 [Nb 2 (μ 2 -S 2 ) 2 (NCS) 8 ] and (Bu 4 N) 4 [Nb 2 (μ 2 -Se 2 ) 2 (NCS) 8 ] are analyzed by XPS and XANES techniques. The largest contributions of S 3 p states of NCS – ligands to the occupied molecular orbitals are found to be near the upper boundary of the valence band while the contributions from dichalcogenide bridging ligands have a more uniform distribution. For the conduction band, the contributions of S 3 p states of NCS – ligands are located deeper whereas the contributions from dichalcogenide bridging ligands are near the lower boundary of the conduction band. The interaction of Nb 4 d and S 3 p /Se 4 p states of dichalcogenide bridges for the HOMO has an antibonding character, which is bonding for all the other occupied molecular orbitals and antibonding for all unoccupied molecular orbitals.