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The paper presents an investigation into the reduction and adsorption performance of hierarchically structured carbon films (HSCFs). The HSCFs are synthesized from glucose using a molten magnesium catalyst under a layer of molten salts during their reaction with an aqueous sodium permanganate solution at pH values from 1 to 14 and temperatures from 20 to 80 °C. By increasing the temperature from 20 to 80 °C, the reduction and adsorption of Mn (VII) on the HSCFs is accelerated by a factor of 150; moreover, the reaction products are not temperature-dependent. According to Raman and photoelectron spectroscopy data, synthesis in the neutral and basic sodium permanganate solutions produces an "HSCF-sodium-manganese spinel" nanocomposite, the greater part (≈ 80%) of whose manganese is in a tetravalent state, while the remainder is in a trivalent state. The predominant precipitation of manganese spinel nanocrystals on the developed side of the carbon film may be related to the full disappearance of the sp hybridized carbon peak on the XPS spectra. It is shown for the first time that the reactivity of carbon varies with its valence state. Of the three hybridized states of carbon, sp hybridized carbon is demonstrated to have the highest reactivity. It is confirmed that 100% reduction and adsorption from 0.01 to 0.1 M sodium permanganate solutions occur in neutral and basic media. The adsorption capacity of the hierarchically structured carbon film interacting with 0.1 M sodium permanganate solution is more than 450 mg/g, representing a high adsorption performance as compared to other carbon nanomaterials investigated earlier. [ABSTRACT FROM AUTHOR]

The reactions of KI with the KF–KCl–K2SiF6 and KF–KCl–K2SiF6–SiO2 salt systems are studied. The KF–KCl and KF–KCl–KI systems containing both K2SiF6 and SiO2 are studied by Raman spectroscopy. The addition of KI to the KF–KCl–K2SiF6 and KF–KCl–K2SiF6–SiO2 melts induces groups containing Si–I bonds in the molten solid samples. A significant portion of silicon dioxide from the KF–KCl–K2SiF6–SiO2 and KF–KCl–KI–K2SiF6–SiO2 melts crystallizes in the form of silicate structures characteristic of the K2SiO3 phase (K2O·SiO2). The results of Raman spectroscopy are consistent with the X-ray diffraction data for the KF–KCl and KF–KCl–KI melts containing both K2SiF6 and SiO2. The crystallization field of K3SiF7 is retained upon the addition of KI to the KF–KCl–K2SiF6 and KF–KCl–K2SiF6–SiO2 melts. KI introduced into the melt precipitates to form an individual phase during crystallization. Low-intensity peaks corresponding to the crystallization of the α-SiO2 phase are detected for the KF–KCl–K2SiF6–SiO2 and KF–KCl–KI–K2SiF6–SiO2 systems. The KF–KCl–KI–K2SiF6 and KF–KCl–KI–K2SiF6–SiO2 melts are studied by synchronous thermal analysis. Phase transitions probably associated with the transformation of -structures into structures containing are observed at temperatures up to 473 K, which is consistent with the data on the thermal stability of mixed silicon halides. [ABSTRACT FROM AUTHOR]

A series of the Li7−y−3xAlxLa3Zr2−yNbyO12 (y = 0.1–0.25, x = 0–0.25) solid electrolytes were synthesized by sol-gel method and sintered at 1150 °C for 1 h. The phase analysis was done using X-ray diffraction method and Raman spectroscopy; the obtained compounds have a cubic structure Ia-3d. The Li6.6Al0.05La3Zr1.75Nb0.25O12 solid electrolyte has the highest total conductivity, 6.3·10−4 S cm−1 at 25 °C. The growth of Al content in Li6.75−3xAlxLa3Zr1.75Nb0.25O12 system leads to conductivity decreasing and activation energy growth. The conductivity descend can be associated with the decreasing of charge carriers (Li+) amount in the Li6.75−3xAlxLa3Zr1.75Nb0.25O12 structure. Li6.9−3xAlxLa3Zr1.9Nb0.1O12 and Li6.8−3xAlxLa3Zr1.8Nb0.2O12 solid electrolytes with a smaller addition of Nb have lower values of lithium-ion conductivity. Thus, it was concluded that high conductivity of Li6.6Al0.05La3Zr1.75Nb0.25O12 ceramic is caused by the optimal ratio of lithium vacancies and the number of charge carriers in the garnet structure. Thus, obtained solid electrolyte can be used in high-energy lithium and lithium-ion batteries. [ABSTRACT FROM AUTHOR]

A series of the Li7La3Zr2O12–x wt% 40.2Li2O·5.7Y2O3·54.1SiO2 composite electrolytes (x = 1–10) were obtained at 1150 °C for 1 h. According to X-ray diffraction and Raman spectroscopy, the obtained composites with x < 3 had no impurities. The glass additive was partially crystallized in the studied composites. A glass addition of 1 wt% leads to the conductivity growth from 1.5 × 10−4 to 2.8 × 10−4 S cm−1 at 25 °C. With further addition of the glass, the total conductivity of electrolyte decreased. The composite electrolytes with x = 1–3 have higher total conductivity values than the cubic Li7La3Zr2O12 at studied temperature range. It was determined that the glass addition into the cubic Li7La3Zr2O12 increased its stability in contact with air. The composite electrolyte with 1 wt% glass is stable versus metallic lithium at 200 °C. Thus, the new obtained composites can be used as solid electrolytes for high-energy power sources. [ABSTRACT FROM AUTHOR]

High-conductivity NASICON-type solid electrolytes of Li1.5Al0.5Ge1.5(PO4)3 composition have been obtained through glass crystallization. Thermal behavior of the precursor glass has been investigated; glass transition and crystallization temperatures have been determined by DSC. The influence of glass crystallization temperature (750, 800, 820, and 850 °C) on the phase composition, microstructure, molecular structure, and ionic conductivity of Li1.5Al0.5Ge1.5(PO4)3 glass-ceramics has been studied. It was found that the optimum crystallization temperature for obtaining an electrolyte with the highest conductivity (0.39 mS cm−1 at 25 °C) is 820 °C. [ABSTRACT FROM AUTHOR]

Lithium-vanadium oxide with the formal composition Li6V5O15, uniform microsctructure, and the particle size of 100 nm is synthesized by a solution method. The synthesized compound is characterized by the methods of X-ray diffraction analysis, Raman spectroscopy, and synchronous thermal analysis. The total electric conductivity is measured by the method of impedance spectroscopy and its electronic component is estimated by dc method. In the temperature range of 200-400°C, Li6V5O15 represents a mixed electronic- ionic conductor with predomination of the ionic component and is thermally stable up to 550°С. Preliminary tests of a laboratory model of electrochemical cell Li|LiPF6|Li6V5O15 are carried out. [ABSTRACT FROM AUTHOR]

Abstract: 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. [ABSTRACT FROM AUTHOR]

CaV0.5Mo0.5O3 - ϐ with the structure of perovskite is synthesized in an atmosphere of humid hydrogen. It is found that when the material under study is moved into air, a nonequilibrium state forms due to the enhanced concentration of oxygen over the surface of the highly reduced oxide. It is shown that photoinitiated oxidation is observed on the surface of the material under the action of a low-power laser beam (50 mW), where it selectively occurs under a green laser beam (λ = 532 nm). This phenomenon is observed for such materials for the first time. [ABSTRACT FROM AUTHOR]