Vol 60, No 1 (2024)

Perovskite-like materials with mixed ionic and electronic conductivity are considered as promising functional materials for proton-ceramic electrochemical devices. In the present work, a solid solutions series La_0.9Sr_0.1Sc_{1 – x}Mn_xO_{3 – δ}, where B-cation position scandium ions are gradually replaced by manganese ions, was obtained and studied in first time. The obtained materials were certified by X-ray phase analysis, scanning electron microscopy, and energy-dispersive microanalysis. The dopant influence on the sinterability and morphology researched materials is shown. The solid solutions electrical conductivity as a function of temperature and gas phase humidity were investigated by direct current four-probe method.

The paper presents the results of studies of the structural, thermal and transport properties of solid composite electrolytes (1 – x)(C₄H₉)₃CH₃NBF₄ – xC_ND (where C_ND are nanosized diamonds, 0 ≤ x < 1, x is the mole fraction). It has been shown by the Powley method that the crystal structure of the low-temperature phase (C₄H₉)₃CH₃NBF₄ is described by the space symmetry group P4₂/ncm. It was found that the addition of a nanodiamond inert additive leads to an increase in the electrical conductivity of the composite electrolyte by 4 orders of magnitude up to a value of 1.3∙10–3 S/cm at 145°C at x = 0.98. The theoretical dependences describe well the experimental data in the concentration range 0 ≤ x ≤ 0.99 at temperatures of 84 and 127 ^оC.

In the present work, an experimental module for hydrogen purification based on nickel capillaries was fabricated. The module was tested by varying the temperature, the difference in the partial pressure of hydrogen on the feed and permeate sides of the capillaries. The maximum hydrogen flow obtained using a module based on 7 nickel capillaries with a wall thickness of 50 µm was 37.2 ml/min at a temperature of 900 ^оС and a hydrogen pressure of 0.9 atm. The stability of the hydrogen flow during the thermal cycling in the temperature range of 600–800 ^оС for 55 hours is shown.

The present article is devoted to the study of the stability of microtubular membranes based on Ba_0.5Sr_0.5Co_{0.8 – x}Fe_0.2Mo_xO_{3 – δ} oxides obtained by the phase inversion method. The work shows that MT membranes of the composition BSCFMx exhibit long-term stability and resistance to thermal cycling in an air/helium gradient. The maximum oxygen fluxes were achieved using an MT membrane of composition Ba_0.5Sr_0.5Co_0.75Fe_0.2Mo_0.05O_{3 – δ} (JO₂ =7.6 ml*cm^-2min^-1 at Т=850 ^oС and pO_2.1 = 0.21 atm). In this work, a detailed equilibrium phase diagram for the BSCFM5 oxide has been obtained. The absence of unwanted phase transitions has been demonstrated.

Perovskite-like oxides based on lanthanum-strontium ferrites are considered 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 proven to be an effective way to increase their chemical stability. In this paper, for the first time, the results of a study of the permeability of microtubular oxygen membranes based on La_0.5Sr_0.5Fe_{1 – x}Nb_xO_{3 – δ} oxide are presented. The activation energy of oxide bulk diffusion (20±4 kJ/mol) was found.

Composite solid electrolytes based on n-methyl-n-butyl-piperidinium tetrafluoroborate [(CH₃)(C₄H₉)C₅H₁₀N]BF₄–A (where A is γ-Al₂O₃, SiO₂) were synthesized and their thermal and electrically conductive properties have been studied. It was found that the conductivity of the [C₁₀H₂₂N]BF₄–Al₂O₃ composites passes through a maximum at x~0.9 and reaches a value of 4.6·10^-4 S/cm at 130^оC for the 0.1[C₁₀H₂₂N]BF₄–0.9Al₂O₃ composite. The absence of a thermal effect at the melting temperature of the ionic salt, which indicates a high ionic conductivity, indicates that at x ≥ 0.9, n-methyl-n-butyl-piperidinium tetrafluoroborate is in the amorphous state and ion transfer occurs along the ionic salt/oxide phase boundary. In the case of [C₁₀H₂₂N]BF4 – SiO₂ composites, the effect of a heterogeneous dopant on ion transport is less significant and the conductivity is due to the ionic salt of the additive present in the pores.