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Finely dispersed (CeO2)1−x(Sm2O3)x (x = 0.05, 0.10, 0.20) and (CeO2)1−x(Nd2O3)x (x = 0.05, 0.10, 0.15, 0.20, 0.25) powders were synthesized via liquid-phase techniques based on the co-precipitation of hydroxides and were used to obtain ceramic materials comprising fluorite-like solid solutions with CSR in the range 69–88 nm (upon annealing at 1300 °C) and open porosity in the range 0.6–6.2%. The physicochemical properties of the synthesized materials were comparatively characterized. In general, the prepared materials were found to possess a mixed type of electrical conductivity, but in the medium-temperature range, the ionic component was predominant (ion transfer numbers ti = 0.93–0.73 at 300–700 °C). The highest ionic conductivity was observed for CeO2-based samples containing 20 mol.% Sm2O3 (σ700°C = 3.3 × 10−2 S/cm) and 15 mol.% Nd2O3 (σ700°C = 0.48 × 10−2 S/cm) was in the temperature range 500–700 °C. The physicochemical properties (density, open porosity, type and mechanism of electrical conductivity) of the obtained ceramic materials make them promising as solid oxide electrolytes for medium temperature fuel cells.

Finely dispersed (CeO2)1−x(Nd2O3)x (x = 0.05, 0.10, 0.15, 0.20, 0.25) powders are synthesized via liquid-phase techniques based on the co-precipitation of hydroxides and co-crystallization of nitrates. The prepared powders are used to obtain ceramic materials comprising fluorite-like solid solutions with the coherent scattering region (CSR) of about 88 nm (upon annealing at 1300 °C) and open porosity in the range of 1–15%. The effect of the synthesis procedure and sintering additives (SiO2, ZnO) on physicochemical and electrophysical properties of the resulting ceramics is studied. The prepared materials are found to possess a predominantly ionic type of electric conductivity with ion transfer numbers ti = 0.96–0.71 in the temperature range of 300–700 °C. The conductivity in solid solutions follows a vacancy mechanism with σ700 °C = 0.48 × 10−2 S/cm. Physicochemical properties (density, open porosity, type and mechanism of electrical conductivity) of the obtained ceramic materials make them promising as solid oxide electrolytes for medium temperature fuel cells.

Purpose The purpose of this paper is the development of a new numerical method for the calculation of the air-gap magnetic flux harmonics in synchronous machines with permanent magnet (PM) excitation. The harmonic analysis results are used as input data for the eddy-current loss calculation and for the rotor heating evaluation. Design/methodology/approach The method is based on the finite element analysis (FEA). The model takes into account toothed stator design, rotor asymmetrical magnetic reluctance and saturation. At first, a series of static DC magnetic (magnetostatic) simulations is run. Each problem corresponds to specific rotor position and the momentary stator winding currents. The Fourier analysis performed for each problem yields the harmonic spectrum variation in time. Then, a series of AC magnetic (time-harmonic) simulations is run. Each problem corresponds to a specific harmonic. The result is the eddy-current losses distribution. After total loss is calculated, the heat transfer analysis is conducted. Findings The analysis reveals that 90 per cent of losses are located in the sleeve that holds PMs together. Rotor eccentricity brings even harmonics of low magnitude that have little impact on heating. Originality/value In general, the study requires transient electromagnetic analysis with motion. The purposed method allows to simplify the problem. The method is based on static and quasi-static (time-harmonic) problems simulation. It is fast and highly automated. The method allows simultaneous taking into account of tooth-order harmonics, stator winding harmonics and eccentricity for heating calculation.

Nanosized powders as precursors have been synthesized via sol–gel technique to prepare ceramic composites in the LaPO 4 –Y 2 O 3 and LaPO 4 –ZrO 2 systems through normal sintering. Sol–gel technique was based on separate synthesis of LaPO 4 · n H 2 O, Y(OH) 3 , and ZrO(OH) 2 components as sol using “reverse precipitation” (or “reverse flocculation”) technique, and further mixing them together to prepare (1‒ x )LaPO 4 · n H 2 O– x Y(OH) 3 and (1‒ x )LaPO 4 · n H 2 O– x ZrO(OH) 2 compositions as gels. During sol–gel synthesis, formation of hexagonal LaPO 4 · n H 2 O and Y(OH) 3 or monoclinic ZrO(OH) 2 was observed. As-prepared precursors of nanosized powders were then calcined at 850 °C for dehydration of the components and decomposition of yttrium and zirconium hydroxides to obtain nanosized (1‒ x )LaPO 4 – x Y 2 O 3 and (1‒ x )LaPO 4 – x ZrO 2 compositions, where x did not exceed 0.20 mole fraction. Ceramic composites were prepared by sintering these compositions subsequently at 1000, 1200, and 1300 °C for 24 h. Vickers microhardness was found to depend on x and sintering temperature. The influence of yttria and zirconia additions on dispersion of powders, their thermal behavior, specific surface area and ceramic fracture surface of the composites, and their open porosity was discussed. Initial nanosized powders of 0.8LaPO 4 · n H 2 O−0.2Y(OH) 3 (left) and 0.8LaPO 4 · n H 2 O−0.2ZrO(OH) 2 (right) Fracture surfaces of 0.8LaPO 4 –0.2Y 2 O 3 (left) and 0.8LaPO 4 –0.2ZrO 2 (right) ceramic composites sintered at 1300 °C for 24 h. Highlights Sol–gel synthesis of nanopowders-precursors of (1‒ x )LaPO 4 · n H 2 O– x Y(OH) 3 and (1‒ x )LaPO 4 · n H 2 O– x ZrO(OH) 2 using separate and “inverse precipitation” of LaPO 4 · n H 2 O and Y(OH) 3 or ZrO(OH) 2 was performed. Preparation of nanosized (1‒ x )LaPO 4 – x Y 2 O 3 and (1‒ x )LaPO 4 – x ZrO 2 compositions by preliminary calcining not compacting powders at 850 °C was carried out. Sintering at 1000‒1300 °C to obtain (1‒ x )LaPO 4 – x Y 2 O 3 and (1‒ x )LaPO 4 – x ZrO 2 ceramic composites where mole fraction x  ≤ 0.20 was performed. Comparison of fracture surfaces of LaPO 4 , 0.8LaPO 4 –0.2Y 2 O 3 and 0.8LaPO 4 –0.2ZrO 2 ceramic samples sintered at 1000 and 1300 °C (24 h) was done. Comparison of Vickers microhardness values for both systems was presented. The influence of yttria and zirconia additions on dispersion of powders, their thermal behavior, specific surface area, and ceramic fracture surface was discussed.

This work is an attempt to outline the poietic architectonics of denominational realities, as they are present in respective linguistic systems. It presents a lexicon that integrates notions of transcendental reasoning and its poetic realization, such as ekphrasis, poiesis, likeness, acoustic image, affect ,etc.. The work has an ontological goal, to find a way to develop a compassionate type of subjectivity. In this work, I investigate verbal act as a way to submit one’s thinking and perception to the Word-Creator, for the latter to speak itself through them. In this context, self-expression becomes an act of hollowing out of the immanent meanings in the leap of faith that the truth will speak itself into one’s being through the words that simultaneously signify those meanings, and channel what is ineffably meaningful. This work explores likeness between the verbal act and the drawing of an icon, to better formulate a question, as how to treat language in order to create an edifying dialogue between people. I envision that in such a dialogue, one heart speaks to the other not through the exchange of meanings, but rather through the subjective relation to truth that speaks through one’s words. This poetic mode of reasoning revolves around the notion of Symbol understood in spirit of the Christian Orthodox tradition where Symbol denotes simultaneous presence of both the Divine essence and the functional substantiality of objects as they appear to be in the empirical world.

Powders of Sm 0.6 Sr 0.4 CoO 3-δ and La 0.6 Sr 0.4 CoO 3-δ were synthesized using wet chemical technique. Structural and surface properties of synthesized materials were studied by thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), X-ray diffraction (XRD), IR spectroscopy, and scanning electron microscopy (SEM). The influence of pH on the phase state, chemical composition, morphology, and fractal dimension of the synthesized powders were investigated. It was found that the change of pH has the influence on phase composition of synthesized powders. The increase of solution pH allows one to obtain homogeneous samples at lower temperatures down to 900–950 °C. Highlights pH of solution has significant influence on phase transformation of Sm 0.6 Sr 0.4 CoO 3-δ during thermal treatment. The increase of pH leads to the formation of smaller amount of SrCO 3 phase in Sm 0.6 Sr 0.4 CoO 3-δ powders. Suggested approach allows to obtain homogeneous samples at lower temperatures down to 900‒950°C.

Finely dispersed (CeO[sub.2] )[sub.1−x] (Sm[sub.2] O[sub.3] )[sub.x] (x = 0.05, 0.10, 0.20) and (CeO[sub.2] )[sub.1−x] (Nd[sub.2] O[sub.3] )[sub.x] (x = 0.05, 0.10, 0.15, 0.20, 0.25) powders were synthesized via liquid-phase techniques based on the co-precipitation of hydroxides and were used to obtain ceramic materials comprising fluorite-like solid solutions with CSR in the range 69-88 nm (upon annealing at 1300 °C) and open porosity in the range 0.6-6.2%. The physicochemical properties of the synthesized materials were comparatively characterized. In general, the prepared materials were found to possess a mixed type of electrical conductivity, but in the medium-temperature range, the ionic component was predominant (ion transfer numbers t[sub.i] = 0.93-0.73 at 300-700 °C). The highest ionic conductivity was observed for CeO[sub.2] -based samples containing 20 mol.% Sm[sub.2] O[sub.3] (σ[sub.700°C] = 3.3 × 10[sup.−2] S/cm) and 15 mol.% Nd[sub.2] O[sub.3] (σ[sub.700°C] = 0.48 × 10[sup.−2] S/cm) was in the temperature range 500-700 °C. The physicochemical properties (density, open porosity, type and mechanism of electrical conductivity) of the obtained ceramic materials make them promising as solid oxide electrolytes for medium temperature fuel cells.

Electrodes of two types have been fabricated for a use in an experimental microbiological fuel cell (MFC). One series consists of a piece of steel mesh covered with a coating of electrodeposited cobalt (II) hydroxide. The other one includes a silicon oxide under-layer obtained with a sol–gel synthesis. Composition, morphology, and electrochemical behavior of the materials have been examined using X-ray photoelectron spectroscopy, scanning electron microscopy, and cyclic voltammetry, respectively. Oxidation state of +2 has been assigned to cobalt species in the as-deposited material. Dynamic cycling of potentials of modified electrodes has resulted in the increase of the cobalt oxidation state in the tested material. Formulas of the cobalt compounds have been proposed. The optimization of electrolyte composition (1 M CH 3 COOK/0.004 M KOH) has allowed to reduce the pH of the solution and extend the voltage window by 100 mV in the positive range of potentials. Cyclic voltammetric experiments have revealed a better cyclability for silica pre-modified electrodes than for electrodes without the under-layer. Microbiological tests have shown compatibility of the obtained electrode materials with bacteria Geobacter sulfurreducens . Two pieces of steel mesh are taken. One of them is used for electrodeposition of cobalt hydroxide without any previous processing. The other one is pre-coated with a layer of silicon oxide before the electrodeposition of cobalt hydroxide. Then cyclic voltammograms of both modified electrodes are compared to show a better electrochemical performance for the electrode with the silica layer. Highlights Silica under-layer improves electrochemical performance of the material based on cobalt (II) hydroxide. The use of an optimized electrolyte composition diminishes pH of solution and extends the voltage range. The electrodes modified with Co(OH) 2 are more preferential for Geobacter sulfurreducens than bare steel mesh.