The photocatalytic properties of single-phase sample Sr 2 Mn 0.4 Ti 0.6 O 4 is studied as a representative of a series of Sr 2 Mn x Ti 1-x O 4 solid solutions (x = 0.05, 0.15, 0.25, 0.4) obtained by the SHS.The sample annealed at 1200 • C is characterized by a uniform distribution of Sr, Ti and Mn in the oxidation degree (4+) inside the aggregates, the average size of which does not exceed 1 µm.According to UV-Vis-NIR spectroscopy data, a narrowing of the band gap of Sr 2 TiO 4 from 3.16 to 1.8 eV is observed when it is doped with 40 mol% of manganese.This is due to the high photoactivity of Sr 2 Mn 0.4 Ti 0.6 O 4 in the HQ oxidation reaction in UV and blue light.

A layered perovskite-like oxides LaxSr2−xTi1−x/2Cux/2O4 (x = 0.2, 0.3, 0.5) with a K2NiF4-type structure were obtained. The introduction of copper into the titanium sublattice reduces the band gap. Copper in these materials serve as a photoactivity regulator and is presented in two oxidation states in accordance with optical, voltammetric and EPR data. LaxSr2−xTi1−x/2Cux/2O4 (x = 0.2) exhibits the greatest photoactivity in the oxidation of phenolic compounds and As(III) under the influence of UV and blue light; with increasing degree of substitution x, the photoactivity of LaxSr2−xTi1−x/2Cux/2O4 decreases. This is explained by the formation of a magnetic polaron, which is observed in LaxSr2−xTi1−x/2Cux/2O4 (x = 0.5) in the temperature range from 50 to 200 K and is proven by ESR method. The expansion of the spectral range of LaxSr2−xTi1−x/2Cux/2O4 to the visible region is explained by the formation of acceptor levels ( Cu^2 + + e^ - →Cu^ + / Cu^ + + h^ + →Cu^2 + ) in the band gap of Sr2TiO4, which increases the efficiency of separation of photogenerated electron–hole pairs. The presence of Cu (I) в LaxSr2−xTi1−x/2Cux/2O4 enhance photoactivity through the formation of active superoxygen radical on its surface ( Cu^ + + O_2( ad)→Cu^2 + +·O_2^ - ).

X-ray powder diffraction, Raman spectroscopy, HRTEM, electron diffraction and differential thermal analysis methods were used to study structural and spectroscopic properties and thermal stability of the products obtained by air-thermolysis of Ti-glycolate in the temperature range 300-450 degrees & Scy;. TiO2/C composites were obtained, which have anatase/brookite matrix with a variable degree of crystallinity and contain different contents of brookite and free polymeric-like carbon with COO- groups. It was found that the residual content of carbonaceous component and the intensity of exothermal decomposition of Ti-glycolate have an effect on the formation of brookite-rich TiO2 matrix. Correlations between the phase composition and the free carbon content suggest that during crystallization brookite/carbon nanoparticles are more stable than anatase/carbon nanoparticles. PEC tests demonstrated that the composite photoanode, which has the greatest degree of crystallinity, the optimal carbon content and is most enriched with brookite, exhibits the greatest incident photon-to-current conversion efficiency (IPCE), and its IPCE peak value is twice as great as the IPCE peak value for Degussa P25. The increased IPCE value is associated with the preferable formation of carbon/brookite/anatase heterostructures. The carbon component has an optical gap of approx. 1.1 eV, and at the optimal contents it ensures efficient photogeneration and transfer of electrons into the conduction band of brookite and then into the conduction band of anatase. HRTEM study demonstrated the formation of such heterostructure with anatase/ brookite heterojunction.

layered perovskite-like oxides La x Sr 2− x Ti 1− x /2 Cu x /2 O 4 ( x = 0.2, 0.3, 0.5) with a K 2 NiF 4 -type structure were obtained. The introduction of copper into the titanium sublattice reduces the band gap. Copper in these materials serve as a photoactivity regulator and is presented in two oxidation states in accordance with optical, voltammetric and EPR data. La x Sr 2− x Ti 1− x /2 Cu x /2 O 4 ( x = 0.2) exhibits the greatest photoactivity in the oxidation of phenolic compounds and As(III) under the influence of UV and blue light; with increasing degree of substitution x , the photoactivity of La x Sr 2− x Ti 1− x /2 Cu x /2 O 4 decreases. This is explained by the formation of a magnetic polaron, which is observed in La x Sr 2− x Ti 1− x /2 Cu x /2 O 4 ( x = 0.5) in the temperature range from 50 to 200 K and is proven by ESR method. The expansion of the spectral range of La x Sr 2− x Ti 1− x /2 Cu x /2 O 4 to the visible region is explained by the formation of acceptor levels ( Cu^2 + + e^ - →Cu^ + / Cu^ + + h^ + →Cu^2 + ) in the band gap of Sr 2 TiO 4 , which increases the efficiency of separation of photogenerated electron–hole pairs. The presence of Cu (I) в La x Sr 2− x Ti 1− x /2 Cu x /2 O 4 enhance photoactivity through the formation of active superoxygen radical on its surface ( Cu^ + + O_2( ad)→Cu^2 + +·O_2^ - ).

In this paper, the results of studying the formation conditions, crystal structure, thermal, spectral, and optical properties, as well as the electronic band structure of cobalt-doped zinc glycolate Zn 1 − x Co x (OCH 2 CH 2 O) (0˂x ≤ 0.2) are presented. Using X-ray powder diffraction data, it was shown that solid solutions are obtained by partial substitution of cobalt for zinc, while maintaining the crystal structure of Zn(OCH 2 CH 2 O). The vibrational spectra of Zn 1 − x Co x (OCH 2 CH 2 O) are identical to those of Zn(OCH 2 CH 2 O) and correlate completely with the results of structural analysis. As a result of heating in air at 600–900 °C, glycolate Zn 1x Co x (OCH 2 CH 2 O), where 0˂x ≤ 0.1, turns into oxide of the composition Zn 1 − x Co x O with wurtzite structure, whose powders have a deep green color (Rinman’s green). The UV-Vis-NIR spectra of Zn 1 − x Co x O contain bands typical of Co 2+ ion transitions in the tetrahedral environment. When Zn 1 − x Co x (OCH 2 CH 2 O) is heated in helium atmosphere, composites (1-x)ZnO:xCo:nC are formed that include a phase with wurtzite structure, metallic cobalt, and elemental carbon. The electronic band structure, optical characteristics, and isosurfaces of wave functions of pure and cobalt-doped zinc glycolate and oxide were calculated. This allowed us to establish the reasons for the increase in the band gap width in glycolate compared to the oxide and its decrease during doping.

In the development of nanostructured V2O3 materials, the topical issue is to elucidate the factors that affect the temperature of a metal-insulator transition (MIT). In this work, we study the structural, magnetic and electrical properties of V2O3 thin-walled microsphere prepared by spray-pyrolysis (SP). Low-temperature XRD and TEM revealed that SP-microspheres contain the anisotropic (50x20 nm) nanocrystallites with a preferred (001)orientation along the sphere surface and show moderate biaxial compressive stresses. SP-aggregates exhibit a high concentration of intercrystallite boundaries and inner pores, which induce high lattice microstrains. Structural, magnetic and electrical properties showed no evidence of MIT down to 100 K. NMR investigations indicated that antiferromagnetic areas appear at temperatures below 115 K. Comparative studies were performed on V2O3 50 nm nanoparticles prepared by thermolysis using the same parent vanadyl solution. The findings suggest that a high defect concentration and microstrains rather than compressive stresses lead to the suppression of MIT.

The crystal structure, magnetic ordering, and dielectric characteristics of polycrystalline powder samples of La2NiMn1-xRuxO6 (x = 0.25-0.75) solid solutions have been studied. The X-ray diffraction results were analysed in detail, and reliably show that all compounds have a monoclinic (P2(1)/n) structure with Ni and Mn/Ru ions occupying the 2c and 2d sites, respectively. Magnetic susceptibility measurements reveal a ferromagnetic order for La2NiMn0.75Ru0.25O6 and La2NiMn0.5Ru0.5O6. The ferromagnetic transition temperature decreases from 200 K for La2NiMn0.75Ru0.25O6 to 175 K for La2NiMn0.5Ru0.5O6. Dielectric measurements show large dielectric constants (similar to 10(4)) at room temperature. In addition, the temperature-dependent loss-tangent Tan delta(T) curves reveal relaxation characteristics due to charge transfer between nearest cations.

This article presents new findings obtained from the study of formation conditions, crystal structure, thermal, spectral, optical properties and electronic band structure of zinc glycolate Zn(OCH2CH2O). This compound was synthesized by heating the solutions of zinc formate Zn(HCOO)2middot2H2O in ethylene glycol (A) or in a mixture of ethylene glycol and distilled water (B). The crystal structure of Zn(OCH2CH2O) has been studied using the X-ray powder diffraction method. It is shown that the crystal structure is built via zigzag joining of [Zn4O12C8H16] tetracycles with the tetrahedrally coordinated zinc (ZnO4). Zinc atoms inside the tetracycles and the tetracycles themselves are interconnected with oxygen bridges. Complex anions OCH2CH2O2-are bonded to zinc atoms by chelation. The unit cell parameters of Zn(OCH2CH2O) are as follows: the tetragonal structure, space group I41/a (88-2), Z = 16, a = b = 11.08673(9) A, c = 11.5902(1) A, V = 1424.62(2) A3. The IR and Raman spectra of Zn(OCH2CH2O) correlate fully with the results of structural analysis. Under UV excitation, the luminescence spectra of Zn(OCH2CH2O) samples synthesized following the methods (A) and (B) are characterized by emission maxima at 460 nm (blue luminescence) and 540 nm (yellow-green luminescence), respectively. Yellow-green luminescence is due to the presence of an ad-mixture of zinc oxide nanoparticles of size 10 nm in the sample. The electron density functional method is employed to study the electronic band structure and chemical bonding in Zn(OCH2CH2O). It is shown that the 3dZn orbitals are covalently bonded to 2pO orbitals so that an octagon is formed, where the zinc atoms of four neighboring ZnO4 tetrahedrons are linked through their vertices. The feasibility of synthesizing a layered structure of Zn(OCH2CH2O) is analyzed on the basis of ab initio calculations and Voigt-Reuss-Hill theory.(c) 2022 Elsevier B.V. All rights reserved.

The effect of annealing temperature on the optical properties of nanosized cadmium oxide with rock-salt structure synthesized by thermal treatment of cadmium formate Cd(HCOO)(2)center dot 2H(2)O was studied using X-ray diffraction and UV-Vis-NIR spectroscopy methods. The samples were obtained by heating of as-prepared cadmium oxide in air at a temperature successively increasing from 500 to 900 degrees C with an interval of 50 degrees C. The exposure time at each temperature was 1 h. It was established that as a result of annealing in air in this thermal regime the CdO band gap decreased from 1.95 to 1.50 eV with the corresponding change of the powder color from reddish-brown to black. The particle size estimated by the Williamson-Hall method and the density decreased from 85.5 to 79.8 nm and from 8.24 to 8.20 g/cm(3), respectively. With the use of the first-principle calculations of the electronic band structure, optical absorption and vacancy formation energy it was shown that the reason of the band gap narrowing is the appearance of vacancies in the CdO oxygen sublattice, the concentration of which grows with increasing annealing temperature.

The new cathode materials Pr1-xSrxFe1-yCoyO3 (0 <= x <= 0.4; y = 0.2, 0.5) for SOFC have been studied. The materials were synthesized by the self-propagating high-temperature synthesis method. It was shown that the chemical activity of Pr1-xSrxFe1-yCoyO3 (PSFC) with respect to Zr0.84Y0.16O2-delta (YSZ) electrolyte increases with increasing concentration of Sr and Co, whereas the interaction with Ce0.73Gd0.27O2-delta (GDC) electrolyte was not found. The thermal expansion of praseodymium ferro-cobaltite nonlinearly depends on the Sr content with a minimum at x = 0.3. The conductivity of the investigated materials increases with an increase of Sr and Co content. The cathode materials in contact with YSZ have a high polarization resistance (a few Omega cm(2) at 850 degrees C) due to their chemical interaction. Replacement of YSZ electrolyte with GDC results in the reduction of the polarization resistance by an order of magnitude. The Pr0.6Sr0.4Fe0.8Co0.2O3 in contact with GDC has the lowest polarization resistance of 0.05 Omega cm(2) at 850 degrees C. (C) 2021 Elsevier B.V. All rights reserved.

С использованием формиатогликолятных комплексов ZnCu(HCOO)(OCHCHO) (0 ≤ х ≤ 0,15) получены твердые растворы ZnCuO с 1D и композиты ZnCuO / CuO со сферической морфологией агрегатов соответственно. Материалы апробированы в реакции фотоокисления As(III) при воздействии ультрафиолетового и видимого излучения. Установлено, что медь является эффективной допирующей примесью в составе твердого раствора ZnCuO (0 ≤ х ≤ 0,1). Присутствие ее в оболочке композита ZnCuO / CuO негативно влияет на фотоактивность материала вплоть до подавления фотокатализа в видимом световом диапазоне. Показана также сорбционная эффективность материалов к мышьяку независимо от состава и морфологии материала. Согласно данным рентгеновской фотоэлектронной спектроскопии на поверхности образцов после сорбции мышьяк находится преимущественно в виде As(III) . 1D solid solutions ZnCuO and composites ZnCuO / CuO with spherical morphology of aggregates from formate glycolate complexes ZnCuO (HCOO)(OCHCHO) (0 ≤ x ≤ 0,15) were obtained. All materials have been tested in the reaction of As(III) photooxidation upon exposure to ultraviolet and visible radiation. It was found that copper is an effective doping impurity in the composition of the solid solution ZnCuO (0 ≤ x ≤ 0,1). Its presence in the shell of the ZnCuO / CuO composite negatively affects the photoactivity of the material up to suppression of photocatalysis in the visible light range. The sorption efficiency of materials for arsenic is also shown, regardless of the composition and morphology of the material. According to x-ray photoelectron spectroscopy data, the surface of the samples after sorption contains arsenic mainly in the form of As(III).

We report the preparation of ceramics on the basis of solid-solutions La1,8Sr0,2Ni0,8Cu0,2O4 with K2NiF4-type structure by new method and systematically study their structure, morphologies, and dielectric properties. Different values of frequency-independent dielectric constants are observed at wide region of frequencies 10-10(7) Hz in the ceramics prepared before and after thermobaric treatment of the sample. The highest permittivity epsilon is of order 10(3) (at ambient temperature) in the frequency range from 1 kHz to 10 MHz after the sample treatment at 1000 degrees C and P = 4 GPa during 5 min. An obvious change of grain morphology and sufficient change of structural polyhedra anisotropy in La1,8Sr0,2Ni0,8Cu0,2O4 was observed during the thermobaric treatment. Results of the dielectric properties investigations indicate that possible reasons of the high-permittivity origin are specifics of layered structure and charge polarization associated with it, Maxwell-Wagner polarization at the grain boundaries and inhomogeneities and hopping conduction mechanism of small polaron.

Gallium-doped aluminum oxide (Al1-xGax)(2)O-3 with gamma-Al2O3 (spinel) structure has been synthesized by the precursor method using the formate Al1-xGax(OH)(HCOO)(2) as a precursor. The examination of Al1-xGax(OH)(HCOO)(2) (x = 0.0, 0.1, 0.2, 0.3, 0.4) was carried out by X-ray powder diffraction, Infrared, Raman spectroscopy and differential-thermal methods. The solid solutions gamma-(Al1-xGax)(2)O-3 with x <= 0.2 have been synthesized by thermolysis of precursors in helium atmosphere at 700 degrees C; they exhibit white-blue emission under UV excitation, whose intensity lowers with increasing dopant concentration. As an independent method, the DFT calculations confirmed thermodynamically the stability field of gamma-(Al1-xGax)(2)O-3 solid solutions and the NMR data on relative abundance of Al and Ga within the tetrahedral and octahedral sites in the metal sublaltice furthermore, the structural and thermodynamic properties of carbon-containing impurities within these compounds were suggested theoretically as possible models of luminescence emission centers. The experimentally observed Ga-dependent quenching of luminescence was explained using the competition between C2p and Ga4p states within the band gap of gamma-Al2O3. (C) 2019 Elsevier B.V. All rights reserved.

Layered perovskite-like oxides LnSr2CuTiO6.5 (Ln = La, Nd, Pr) were prepared, of them, the Pr and Nd compounds were for the first time. Their crystal-chemical characteristics and dielectric properties were studied. The dielectric permeability of the compounds was shown to increase considerably after thermobaric treatment (TBT) due to the effects of temperature and high pressure on the anisotropy of interatomic distances in coordination polyhedra (Ln, Sr)O9, (Cu, Ti)O6, and (Ln, Sr)O12. All the oxides studied have an activation conductivity type.

Stable ferromagnetic solid solutions of the composition Mg1-xFexO, where 0 <= x <= 0.075, have been synthesized by the low-temperature precursor method using the mixed formate Mg1-xFex(HCOO)(2)center dot 2H(2)O as a precursor. At iron concentrations of more than 7.5 at.%, an impurity phase MgFe2O4 with cubic spinel structure was observed in the samples. The study of the magnetic properties of Mg1-xFexO at the temperatures 5 and 300 K revealed that they are ferromagnetics, whose magnetization increases with growing iron concentration, both at low and room temperature, reaching the maximal values for the sample with x = 0.075. The main mechanism for the stabilization of ferromagnetism is the interaction of Fe2+ ions by means of 90 degrees superexchange through oxygen atoms as was shown on the basis of electronic band structure calculations. (C) 2019 Elsevier B.V. All rights reserved.

The low-dimensional maghemite γ-Fe2O3 has been synthesized by the precursor method. The basic formate of the composition Fe(OH)(HCOO)2 produced by an original technique was used as a precursor. A study of the magnetic and adsorption properties of the synthesized maghemite showed that it is ferrimagnetic in a wide temperature interval and an effective sorbent for removal of bivalent copper ions from aqueous solutions. The process of adsorption of Cu2+ ions by γ-Fe2O3 powder is described by the Langmuir equation. A comparison of the obtained parameters of the Langmuir equation with available literature data reveals that, allow for the specific surface area, the maghemite powder synthesized in this work surpasses the maghemite samples produced by other methods in the adsorption capacity with respect to copper ions.

Low-dimension ferromagnetic maghemite γ-Fe 2 O 3 was synthesized through a precursor route, using basic iron formate Fe(OH)(HCOO) 2 as a precursor. Conditions of formation of γ-Fe 2 O 3 and the temperature range of its existence on heating in air were determined. The saturation magnetization of γ-Fe 2 O 3 produced through heating the precursor at 350°C 57.5 ( T = 4.2 K) and 43.8 emu/g ( T = 300 K).