The discharge characteristics of the batteries of thermally activated chemical current sources containing CoCl 2 –CoF 2 mixtures as positive electrodes are studied. The compositions and morphologies of the reduction products of the cathodic materials are determined. The use of the mixtures instead of individual cobalt halides makes it possible to stabilize the discharge characteristics and to decrease the discharge temperature of the current source battery. The reduction of Co 2+ to metallic Co 0 occurs under diffusion-controlled conditions.

Samples from the Li2 – 2xMxZrO3 (M = Ca, Zn), Li2 –xZr1 –xNbxO3, and Li2 +xZr1– xYxO3 systems were synthesized by conventional solid-state reaction. Estimated domains of Li2ZrO3-based solid solutions were established for all above-mentioned systems. The transport properties of the samples (temperature and composition dependences of their conductivity, and the conductivity activation energy) were studied by electrochemical impedance spectroscopy in the temperature range from 300 to 600°С. The most probable lithium-ion migration mechanisms depending on the Li2ZrO3 crystal structure were discussed. According to the obtained results, the synthesized materials are typical solid electrolytes with extrinsic disorder and quite low ionic conductivity (σ ∼ 10–2 –10–5 S cm–1).

In order to develop economically competitive solid oxide fuel cell (SOFC) systems it is necessary to design new functional materials with the purpose of enhancing their performance, extending operational lifetime and reducing the cost. The present work focuses on the study of Pr2-xCaxNiO4+δ cathode materials prepared by a simple and cheap conventional solid state reaction method. The structure, oxygen nonstoichiometry, electrical properties and chemical compatibility of the materials with a number of well-known oxygen ion and proton conducting electrolytes were systematically investigated. Chemical composition (Ca content) and technological factors (powders pre-history, electrodes' sintering temperature), as well as external parameters (temperature, air humidity) were correlated with the electrochemical performance of the electrodes to determine the optimal compositions and conditions. Based on this study and testing results of the single anode-supported cell with BaCe0.89Gd0.1Cu0.01O3-δ electrolyte, the Pr1.7Ca0.3NiO4+δ-based electrode compositions are proposed for preferred usage in SOFCs in place of Pr2NiO4+δ electrode.

The effective operation of protonic ceramic electrochemical cells requires the design of electrolytes having not only high ionic conductivity, but also excellent stability with respect to carbonisation. In the present work, the La-based oxides ( La1-xBaxYbO3-delta, 0.03 <= x <= 0.10) are proposed as a possible alternative to the convenient Ba (Ce,Zr)O-3-based electrolytes due to their high chemical stability. It was discovered that Ba-doping results in a deterioration of sintering behaviour; as a result, the relative density decreases and open porosity appears (for x = 0.10). A thorough analysis of transport properties by means of AC and DC measurement techniques enables a selection of the La0.97Ba0.03YbO3-delta sample, which demonstrates the highest conductivity compared with those samples where x = 0.5 and 0.10. Due to its excellent densification behaviour, stability and ionic conductivity, La0.97Ba0.03YbO3-delta can be considered as a promising proton-conducting electrolyte in the La-based family.

A solid solution of the composition Ca 12–x (Al 14 V x )O 33+ δ (0 ≤ х ≤ 0,07) was synthesized. A combination of methods established the charge state of vanadium in a solid solution. The principle of filling with a dopant crystallographic positions in the structure of mayenite is proposed: vanadium cations replace a small number of aluminum positions, presumably in octahedral coordination. The temperature dependence of the electrical conductivity of Ca 11,93 (Al 14 V 0,07 )O 33+ δ was studied by the impedance spectroscopy. It is shown that doping of mayenite with vanadium increases the value of electrical conductivity by an order of magnitude.

Методами просвечивающей электронной микроскопии и микродифракции исследованы нанотонкие пространственные диссипативные структуры (ПДС), полученные термоградиентной обработкой аморфной плёнки селена путём одностороннего нагрева её нижней поверхности при Т = 413 К. Установлено, что полученные нанотонкие ПДС гексагонального селена обладают специфическим искривлённым габитусом и нелинейной веерообразной системой изгибных контуров на их электронно-микроскопическом изображении; решётка нанотонких ПДС испытывает упругопластическое ротационное искривление вокруг трёх взаимно перпендикулярных направлений; углы ротации решётки нанотонких ПДС гексагонального селена достигают: вокруг [001] 25o, вокруг направления, перпендикулярного [001] и лежащего в плоскости аморфной плёнки, 32o, вокруг направления, перпендикулярного первым двум и не лежащего в плоскости аморфной пленки, 35o.

In the work, new lithium-conducting solid electrolytes based on lithium zirconate are synthesized. They are obtained by doping Li8ZrO6 phase with isostructural Li7TaO6. It is shown that in the Li8– xZr1– xTaxO6 system, a series of solid solutions х = 0−0.5 based on Li8ZrO6 form. The conductivity of synthesized Li8 ‒ xZr1 – xTaxO6 solid solutions increases by 1–2 orders of magnitude as compared with undoped zirconate Li8ZrO6 due to the formation of lithium vacancies in the tetra- and octahedral layers of the structure. All-solid-phase electrochemical cells with Li7.85Zr0.85Ta0.15O6 electrolyte, 0.75Li2SnMo3O12 ∙ 0.25B2O3 glass-ceramic anode, and 0.2Li2O · 0.2LiF · 0.45V2O5 · 0.25B2O3 cathode are electrochemically tested. It is shown that the resistance of 0.75Li2SnMo3O12 · 0.25B2O3|Li7.85Zr0.85Ta0.15O6|0.2Li2O · 0.2LiF · 0.45V2O5 · 0.25B2O3 cell decreases after the charge—discharge cycling.

Solid solutions of composition Ca12-x(Al14Vx)O33+δ (0 ≤ x ≤ 0.07) were synthesized. The V oxidation state in the solid solution was found using a combination of methods. The principle for filling mayenite crystallographic positions with dopant proposed that V cations replace a few Al positions, presumably in octahedral coordination. The temperature dependence of Ca11.93(Al14V0.07)O33+δ electrical conductivity was studied by impedance spectroscopy. The electrical conductivity of V-doped mayenite was shown to increase by an order of magnitude.

A feasibility of obtaining hybrid nanosystems consisting of copper, copper oxides, tetragonal or cubic oxide tungsten bronze (OTB) by means of electrodeposition from the polytungstate melts at 973 and 1023 K was studied. The formation regularities of various hybrid nanosystems were established based on a data of electrochemical techniques, X-ray diffraction phase analysis (XRD), and scanning electron microscopy (SEM). A Cu (mesh)/Cu2O/OTB hybrid system with catalase activity was obtained during electrodeposition from the K2WO4 - Na2WO4 (1:1) - 50 mol% WO3 melt at 973 K. (C) 2019 The Electrochemical Society.

Reversible protonic ceramic cells (rPCCs) combine two different operation regimes, fuel cell and electrolysis cell modes, which allow reversible chemical-to-electrical energy conversion at reduced temperatures with high efficiency and performance. Here we present novel technological and materials science approaches, enabling a rPCC with symmetrical functional electrodes to be prepared using a single sintering step. The response of the cell fabricated on the basis of P–N–BCZD|BCZD|PBN–BCZD (where BCZD = BaCe0.5Zr0.3Dy0.2O3−δ, PBN = Pr1.9Ba0.1NiO4+δ, P = Pr2O3, N = Ni) is studied at different temperatures and water vapor partial pressures (pH2O) by means of volt-ampere measurements, electrochemical impedance spectroscopy and distribution of relaxation times analyses. The obtained results demonstrate that symmetrical electrodes exhibit classical mixed-ionic/electronic conducting behavior with no hydration capability at 750 °C; therefore, increasing the pH2O values in both reducing and oxidizing atmospheres leads to some deterioration of their electrochemical activity. At the same time, the electrolytic properties of the BCZD membrane are improved, positively affecting the rPCC’s efficiency. The electrolysis cell mode of the rPCC is found to be more appropriate than the fuel cell mode under highly humidified atmospheres, since its improved performance is determined by the ohmic resistance, which decreases with pH2O increasing.

Nanothin spatial dissipative structures (SDSs) produced by thermal gradient processing of an amorphous selenium film by means of one-sided heating of its lower surface at T = 413 K have been studied by transmission electron microscopy and microdiffraction. It has been established that the resulting nanothin SDSs of hexagonal selenium possess a specific curved habit and a nonlinear fan-shaped system of bending contours in their electron-microscopic image; the lattice of nanothin SDSs undergoes elastic-plastic rotational curvature around three mutually perpendicular directions; the lattice rotation angles of nanothin SDSs of hexagonal selenium reach 25° around [001], 32° around the direction perpendicular to [001] and lying in the plane of the amorphous film, and 35° around the direction perpendicular to the first two directions and not lying in the plane of the amorphous film.

Effect of magnesium on the sinterability, phase composition, microstructure, and transport properties of proton-conducting materials of composition LaY1–xMgxO3–δ (х = 0, 0.05, 0.1) was studied. Ceramic samples were obtained by using the citrate-nitrate synthesis method at various sintering temperatures (1250–1400°C). It was shown that, for the samples with x = 0.05 and 0.1, the relative density was no less than 95% at a sintering temperature of 1350°C, whereas undoped lanthanum nitrate has this density at 1450°C. An X-ray diffraction analysis and scanning electron microscopy demonstrated that introduction of a small amount of magnesium (x = 0.05) is sufficient for forming the single-phase and high-dense ceramics. Electrical conductivity data show that the LaY0.95Mg0.05O3–δ sample has high overall and ionic conductivities.

Calcium gallate Ca5Ga6O14 is synthesized by solid-phase means. Its melting point is 1325 ± 2°C. A phase transition of the second kind is observed in the temperature interval of 750–800°C. The temperature dependence of a thermal linear expansion coefficient within 200–900°C is given. Vibrational spectroscopy data confirm that Ca5Ga6O14 contains not only GaO4 tetrahedra but also GaO6 octahedra.

Lithium metazirconate Li2ZrO3 was synthesized by various methods, and its electric conductivity was studied in the range 300–600°C. For the sample obtained by solid-phase synthesis, the temperature dependence of conductivity is linear in the Arrhenius coordinates and coincides with the literature data for Li2ZrO3 obtained by the similar procedure. The sample synthesized and sintered in vacuum has higher electric conductivity, but contains a Li2CO3 impurity. Possible reasons for the abrupt change in the conductivity of Li2ZrO3 at 430–470°C reported in some works were considered.

Твердофазным методом синтезирован оксигаллат кальция Ca5Ga6O14. Установлено, что температура его плавления составляет 1325±2 °C. Обнаружен фазовый переход второго рода в температурном интервале 750-800 °C. Приведена температурная зависимость коэффициента термического линейного расширения в интервале 200-900 °C. Методами колебательной спектроскопии подтверждено, что структура Ca5Ga6O14 содержит не только GaO4 тетраэдры, но и GaO6 октаэдры.

Reversible protonic ceramic cells (rPCCs) combine two different operation regimes, fuel 11 and electrolysis modes, which allow reversible chemical-to-electrical energy conversion at reduced 12 temperatures with high efficiency and performance. Here we present novel technological and 13 materials science approaches, enabling a rPCC with symmetrical functional electrodes to be 14 prepared using a single sintering step. The response of the cell fabricated on the basis of P–N– 15 BCZD|BCZD|PBN–BCZD (where BCZD = BaCe0.5Zr0.3Dy0.2O3–δ, PBN = Pr1.9Ba0.1NiO4+δ, P = Pr2O3, 16 N = Ni) is studied at different temperatures and water vapor partial pressures by means of volt17 ampere measurements, electrochemical impedance spectroscopy and distribution of relaxation 18 times analyses. The obtained results demonstrate that symmetrical electrodes exhibit classical 19 mixed-ionic/electronic conducting behavior with no hydration capability at 750 °C; therefore, 20 increasing the pH2O values in both reducing and oxidizing atmospheres leads to some deterioration 21 of their electrochemical activity. At the same time, the electrolytic properties of the BCZD membrane 22 are improved, positively affecting the rPCC’s efficiency. The electrolysis mode of the rPCC is found 23 to be more efficient than the fuel cell mode under highly humidified atmospheres, since its 24 performance is determined by the ohmic resistance, which decreases under respectively less humid 25 conditions. 26