The hexagonal perovskite Ba₅In₂Al₂ZrO₁₃ and In³⁺-doped phase Ba₅In_2.1Al₂Zr_0.9O_12.95 were prepared by the solid-state synthesis method. The introduction of indium in the Zr-sublattice was accompanied by an increase in the unit cell parameters: a = 5.967 Å, c = 24.006 Å vs. a = 5.970 Å, c = 24.011 Å for doped phase (space group of P6₃/mmc). Both phases were capable of incorporating water from the gas phase. The ability of water incorporation was due to the presence of oxygen deficient blocks in the structure, and due to the introduction of oxygen vacancies during doping. According to thermogravimetric (TG) measurements the compositions of the hydrated samples corresponded to Ba₅In₂Al₂ZrO_12.7(OH)_0.6 and Ba₅In_2.1Al₂Zr_0.9O_12.54(OH)_0.82. The presence of different types of OH⁻-groups in the structure, which participate in different hydrogen bonds, was confirmed by infrared (IR) investigations. The measurements of bulk conductivity by the impedance spectroscopy method showed that In³⁺-doping led to an increase in conductivity by 0.5 order of magnitude in wet air (pH₂O = 1.92·10⁻² atm); in this case, the activation energies decreased from 0.27 to 0.19 eV. The conductivity−pO₂ measurements showed that both the phases were dominant proton conductors at T < 500 °C in wet conditions. The composition Ba₅In_2.1Al₂Zr_0.9O_12.95 exhibited a proton conductivity ~10⁻⁴ S·cm⁻¹ at 500 °C. The analysis of partial (O²⁻, H⁺, h^•) conductivities of the investigated phases has been carried out. Both phases in dry air (pH₂O = 3.5·10⁻⁵ atm) showed a mixed (oxygen-ion and hole) type of conductivity. The obtained results indicated that the investigated phases of Ba₅In₂Al₂ZrO₁₃ and Ba₅In_2.1Al₂Zr_0.9O_12.95 might be promising proton-conducting oxides in the future applications in electrochemical devices, such as solid oxide fuel cells. Further modification of the composition and search for the optimal dopant concentrations can improve the H⁺-conductivity.

The new phase Ba5In2Al2Zr0.9Nb0.1O13.05 with hexagonal perovskite structure was obtained. The substitution of Zr4+ by smaller Nb5+ was accompanied by the incorporation of the oxygen interstitials and did not lead to a significant change in the lattice parameters. It was established that the investigated sample was capable for water incorporation from the gas phase, the hydration degree value was 0.24 mol H2O. IR-spectroscopy analysis defined the presence of OH−-groups with different thermal stability, which participate in different hydrogen bonds. The new phase Ba5In2Al2Zr0.9Nb0.1O13.05 demonstrates the predominant protonic conductivity at pH2O = 2·10−2 atm and Т600 °C.

Materials with pyrochlore structure A₂B₂O₇ have attracted considerable attention owing to their various applications as catalysts, sensors, electrolytes, electrodes, and magnets due to the unique crystal structure and thermal stability. At the same time, the possibility of using such materials for electrochemical applications in salt melts has not been studied. This paper presents the new results of obtaining high-density Mg²⁺-doped ceramics based on Gd₂Zr₂O₇ with pyrochlore structure and comprehensive investigation of the electrical properties and chemical stability in a lithium chloride melt with additives of various concentrations of lithium oxide, performed for the first time. The solid solution of Gd_2−xMg_xZr₂O_7−x/2 (0 ≤ x ≤ 0.10) with the pyrochlore structure was obtained by mechanically milling stoichiometric mixtures of the corresponding oxides, followed by annealing at 1500 °C. The lattice parameter changed non-linearly as a result of different mechanisms of Mg²⁺ incorporation into the Gd₂Zr₂O₇ structure. At low dopant concentrations (x ≤ 0.03) some interstitial positions can be substituted by Mg²⁺, with further increasing Mg²⁺-content, the decrease in the lattice parameter occurred due to the substitution of host-ion sites with smaller dopant-ion. High-density ceramics 99% was prepared at T = 1500 °C. According to the results of the measurements of electrical conductivity as a function of oxygen partial pressure, all investigated samples were characterized by the dominant ionic type of conductivity over a wide range of pO₂ (1 × 10^–18 ≤ pO₂ ≤ 0.21 atm) and T < 800 °C. The sample with the composition of x = 0.03 had the highest oxygen-ion conductivity (10⁻³ S·cm⁻¹ at 600 °C). The investigation of chemical stability of ceramics in the melt of LiCl with 2.5 mas.% Li₂O showed that the sample did not react with the melt during the exposed time of one week at the temperature of 650 °C. This result makes it possible to use these materials as oxygen activity sensors in halide melts.

The calculating of ionic equilibria in the system «Pb(CH3COO)2 - CdCl2 - Na3C6H5O7 - ‎(NH3)2(CH2)2 - N2H4CS» allowed us to find conditions and concentration regions of PbS and CdS co-deposition. The determined conditions provided the CBD obtaining of CdxPb1−xS (0 ≤ x ≤ 0.033) substitutional solid solutions films with a cubic structure B1 (space group Fm ) with the grains preferred orientation (200). We established the evolution of the surface morphology of the synthesized films from cubic crystallites to hierarchical structure of globular aggregates by scanning electron microscopy. A quantitative analysis of diffraction patterns showed a decrease of microstrains in CdxPb1−xS films by a about factor of 3 with an increase of the cadmium chloride concentration in the reaction mixture from 0.005 to 0.14 mol/l. The excess of the cadmium content, established by EDX analysis, in the studied films as compared to its content in the solid solution is associated with the additional formation of the amorphous CdS phase up to 72 mol %.A Corrigendum is available for this article at https://doi.org/10.15826/chimtech.2021.8.2.12.

Nanocrystalline CdSe films on a frosted glass substrate are synthesized via hydrochemical deposition with sodium selenosulfate using an additive of 5 × 10^–4–10^–3 mol/L copper(II) chloride. It is found that introducing copper(II) chloride into the reaction mixture accelerates the formation of solid phase CdSe and thins the cadmium selenide layer from 240 to 130–160 nm. It is established that doping with copper does not affect the cubic B3 structure (space group \(F\bar {4}3m\)) of the CdSe film, but 10⁻³ mol/L copper(II) chloride in the reactor reduces the period of the crystal lattice from 0.59967 to 0.59899 nm, due to the formation of supersaturated substitutional solid solution Cu_xCd_1−xSe (x = 0.03). The band gap of the CdSe film, calculated according to light transmittance and diffuse reflectance, is 1.8 eV. Adding copper to the film lowers Е_g to 1.6 eV. It is shown that doping with copper results in luminescence in the near-IR spectral range (680–780 nm) and changes conductivity from the n to the p type.

Composites of (1-x)Gd₂Zr₂O₇·xMgO were prepared by mixing gadolinium zirconate with freshly precipitated Mg(OH)₂ followed by heat treatment at 1500 °C. Small concentrations of magnesium oxide dissolved in the complex oxide matrix of Gd₂Zr₂O₇. This led to decrease in the lattice parameters of the matrix phase and a complex redistribution of Gd and Zr over the A and B sublattices. According to the impedance spectroscopy results of the studied samples, for (1-x)Gd₂Zr₂O₇·xMgO (x = 0.05, 0.07, 0.10), the ionic conductivity was slightly higher than that for the undoped Gd₂Zr₂O₇. The share of dominant ion transport did not change upon doping with magnesium oxide. The composites showed chemical resistance in a lithium halide (LiCl) melt and interacted with LiCl-xLi₂O (x = 2 wt.%, 4 wt.%) melts at 650 °C with the formation of a Gd₂O₃ phase or a mixture of phases (Gd₂O₃, Li₂ZrO₃, ZrO₂, LiGdO₂, or LiGdCl₂) on the ceramic surface, respectively.