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^ - ).

The effect of the substitution of [GeO4]4− groups by [PO4]3 in the anionic sublattice of apatite-structure inorganic luminophores activated with Eu3+ ions on their luminescence and crystal chemical properties has been studied. A number of solid solutions with a general formula of Ca2La7.2Eu0.8(GeO4)6−x(PO4)xO2 (x = 0.18, 0.3, 0.48, 0.6, 0.78) have been synthesized. Using the luminescence spectroscopy and electron paramagnetic resonance (EPR) methods, it has been shown that Eu3+ in the structure of the synthesized crystal phosphors undergoes reduction to Eu2+. For compounds with x = 0.18 and 0.48, the effect of the composition on the strength of the crystal field acting on Eu3+ ions has been shown. The phonon sublattice has been studied by the IR and Raman spectroscopy methods. A decrease in the integrated luminescence intensity for the selected type of substitution has been shown. The data obtained can be used to design effective luminophores for some fields of technology, such as the design of scitillation detectors, television systems, and photodiodes.

Photosensitive semiconducting p-type tin(II) sulfide thin films with a band gap of 1.03 ± 0.09 eV have been manufactured in compliance with green chemistry principles using the one-pot approach. To extend the range of sulfidizers suitable for chemical deposition of thin nanostructured SnS films, the efficiency of using sodium thiosulfate solutions has been shown. It has been found that thin SnS films with good adhesion to a dielectric substrate and a coherent scattering region size of ⁓30 nm can be synthesized through hydrolytic decomposition of thiosulfate ions. The conditions for synthesis of SnS have been justified by thermodynamic analysis of ionic equilibria. Quantum-chemical calculations have shown that the p-type conductivity of the synthesized SnS films is most likely due to tin vacancies.

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^ - ).

The article discusses the possibility of obtaining functional composite materials with pronounced photocatalytic properties. A hybrid composite material based on nanoscale cadmium sulfide fixed on a matrix of hydroxyapatite obtained by precipitation from solution has been developed. The initial components and synthesized samples were certified using some modern physico-chemical analysis methods: X-ray phase analysis, energy dispersive X-ray analysis, Raman spectroscopy, scanning electron microscopy, the Brunauer-Emmett-Teller method. The functional characteristics of the developed composite material Ca10(PO4)6(OH)2-CdS, in particular, the photocatalytic activity under the action of ultraviolet or visible radiation, are investigated. The efficiency of using the developed composite material as a photocatalyst was evaluated by the rate of oxidation of p-dihydroxybenzene (hydroquinone). Based on experimental data obtained, the values of the constants of the reaction rate of photocatalytic oxidation of hydroquinone and the time of its half- conversion under various conditions (radiation, the presence of a catalyst) are calculated. It is proved that the developed composite material, which is a hydroxyapatite modified with colloidal CdS particles, has pronounced catalytic properties and is a promising material for use as a photocatalyst. A patent application has been filed for the developed composite material.

Solid of Sr2Ti1-xMnxO4 (x = 0; 0.01; 0.025; 0.05; 0.1) solutions with Raddlesden-Popper structure ( A(n +1)B(n)O(3n+1) , n = 1, structural type K2NiF4) were obtained by a precursor technology. Formate complexes of the corresponding metals synthesized by an original method were used as precursors. The products of thermolysis of the obtained complexes with an organic ligand are isostructural single-phase samples, which crystallize as agglomerates with an average size of 1 mu m. Using energy dispersive X-ray analysis, we established a uniform distribution in the agglomerates of Sr2+ , Ti4+ and Mn4+ . According to electron spin resonance and optical spectroscopy, manganese in titanium-oxygen polyhedra of Sr2Ti1-xMnxO4 is predominantly in oxidation degree 4(+). Increasing the concentration of manganese in the solid solution composition effectively narrows the forbidden band width of strontium titanate from 3.5 eV to 2.5 eV for Sr2Ti0,9Mn0,1O4. The catalytic properties Sr2Ti1-xMnxO4 were analyzed in the oxidation reaction of hydroquinone under irradiation of its aqueous solutions in the ultraviolet and visible spectral ranges. Under the described conditions, all photocatalysts showed a high rate of photooxidation. It was found that the photocatalytic activity of Sr2Ti1-xMnxO4 in 3 consecutive cycles of photooxidation under infrared stimulation exceeds the commercial catalyst Degussa P25 by 4 times.

Проведен сравнительный анализ состава и структуры свежеосажденных осадков гидроксида железа(III), полученных из раствора сульфата железа(II) в присутствии сульфата натрия (400 мг/л) при рН 7 и 8 до и после сорбции на них ионов никеля. Методами ИК- и КР-спектроскопии, рентгенофазового и термогравиметрического анализов показано, что осадки имеют брутто-формулу Fe2O3 × 2H₂O и содержат небольшое количество гетита (α-FeOOH) и лепидокрокита (γ-FeOOH). Установлено, что сорбция ионов никеля на этих осадках не сопровождается хемосорбцией, т.е. образованием смешанных соединений между железом и никелем. Дзета-потенциал частиц осадков при рН 6 имеет положительное значение, а при рН 6 становится отрицательным. Точка нулевого заряда частиц осадков соответствует рН = 6.

The article discusses the possibility of obtaining functional composite materials with pronounced photocatalytic properties. A hybrid composite material based on nanoscale cadmium sulfide fixed on a matrix of hydroxyapatite obtained by precipitation from solution has been developed. The initial components and synthesized samples were certified using some modern physico-chemical analysis methods: X-ray phase analysis, energy dispersive X-ray analysis, Raman spectroscopy, scanning electron microscopy, the Brunauer-Emmett-Teller method. The functional characteristics of the developed composite material Ca10(PO4)6(OH)2-CdS, in particular, the photocatalytic activity under the action of ultraviolet or visible radiation, are investigated. The efficiency of using the developed composite material as a photocatalyst was evaluated by the rate of oxidation of p-dihydroxybenzene (hydroquinone). Based on experimental data obtained, the values of the constants of the reaction rate of photocatalytic oxidation of hydroquinone and the time of its half-conversion under various conditions (radiation, the presence of a catalyst) are calculated. It is proved that the developed composite material, which is a hydroxyapatite modified with colloidal CdS particles, has pronounced catalytic properties and is a promising material for use as a photocatalyst. A patent application has been filed for the developed composite material.

A comparative analysis of the composition and structure of freshly precipitated iron(III) hydroxide precipitates obtained from a solution of iron(II) sulfate in the presence of sodium sulfate (400 mg/L) at pH 7 and 8 before and after sorption of nickel ions on them was carried out. Using IR and Raman spectroscopy and X-ray phase and thermogravimetric analysis, it was shown that the precipitates have the gross formula Fe2O3⋅2H2O and contain small amounts of goethite (α-FeOOH) and lepidocrocite (γ-FeOOH). It has been established that the sorption of nickel ions on these precipitates is not accompanied by chemisorption, i.e., the formation of mixed compounds between iron and nickel. The ζ potential of precipitate particles at pH < 6 has a positive value, and at pH > 6 it becomes negative. The point of zero charge of precipitate particles corresponds to pH 6.

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 Sr2MnxTi1-xO4 2 Mn x Ti 1 - x O 4 solid solutions (x = 0.05, . 05 , 0.15, . 15 , 0.25, . 25 , 0 . 4 ) obtained by the SHS. The sample annealed at 1200 degrees 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 mu m. According to UV-Vis-NIR spectroscopy data, a narrowing of the band gap of Sr2TiO4 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.

Crystal structure and thermoelectric characteristics of the donor-doped CaMnO3-5 are significantly affected by doping elements and oxygen exchange with ambient air occurring at temperatures above 700 K. To investigate the role of dopants and oxygen nonstoichiometry in thermoelectric phenomena, polycrystalline Ca0.95Bi0.025Y0.025MnO3-5 was synthesized and the obtained temperature dependences of thermal and electronic parameters were studied by DFT calculation method. The electrical conductivity has shown to possess a polaronic character up to -700 K with low activation energy. An increase in temperature leads to formation of oxygen vacancies resulting in the appearance of vacancy states inside the band gap and a decrease in its width. The consequence of this is the observed gradual transition to the semiconductor behavior of electrical conductivity explicitly manifested above -1000 K. The obtained experimental figure of merit is shown to be almost an order of magnitude less than the corresponding theoretical one for bulk media, the main part of the deviation is related to the electrical conductivity of the ceramic specimen having a polycrystalline nature. We conclude that the thermoelectric properties of the donor-doped manganese oxide can be significantly improved employing bulk monocrystalline media.

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.

A comparative analysis of the composition and structure of freshly precipitated iron(III) hydroxide precipitates obtained from a sodium sulfate solution (400 mg/L) at pH 7 and 8 before and after the sorption of nickel ions on them was carried out. IR, Raman, and Mössbauer spectroscopy, as well as X-ray diffraction and thermal analyses, have shown that precipitates synthesized from a solution of iron(III) chloride are a two-line ferrihydrite with the gross formula Fe2O3⋅3H2O. It has been established that the sorption of nickel ions on these precipitates is not accompanied with chemisorption, i.e., the formation of mixed compounds between iron and nickel. Their doping with nickel ions also was not observed. It has been found that the ζ potential of ferrihydrite particles at pH < 5.4 has a positive value, whereas it becomes negative at pH > 5.4. The zero-charge point of the precipitate particles corresponds to pH 5.4.

Crystal structure and thermoelectric characteristics of the donor-doped CaMnO3–δ are significantly affected by doping elements and oxygen exchange with ambient air occurring at temperatures above 700 K. To investigate the role of dopants and oxygen nonstoichiometry in thermoelectric phenomena, polycrystalline Ca0.95Bi0.025Y0.025MnO3–δ was synthesized and the obtained temperature dependences of thermal and electronic parameters were studied by DFT calculation method. The electrical conductivity has shown to possess a polaronic character up to ~700 K with low activation energy. An increase in temperature leads to formation of oxygen vacancies resulting in the appearance of vacancy states inside the band gap and a decrease in its width. The consequence of this is the observed gradual transition to the semiconductor behavior of electrical conductivity explicitly manifested above ~1000 K. The obtained experimental figure of merit is shown to be almost an order of magnitude less than the corresponding theoretical one for bulk media, the main part of the deviation is related to the electrical conductivity of the ceramic specimen having a polycrystalline nature. We conclude that the thermoelectric properties of the donor-doped manganese oxide can be significantly improved employing bulk monocrystalline media.

Проведен сравнительный анализ состава и структуры свежеосажденных осадков гидроксида железа(III), полученных из раствора сульфата натрия (400 мг/л) при рН 7 и 8 до и после сорбции на них ионов никеля. Методами ИК-, КР- и мессбауэровской спектроскопии, а также рентгенофазового и термического анализов показано, что осадки, полученные из раствора хлорида железа(III) представляют собой двухлинейчатый ферригидрит с брутто-формулой Fe 2 O 3 ⋅3H 2 O. Установлено, что сорбция на этих осадках ионов никеля не сопровождается хемосорбцией, т.е. образованием смешанных соединений между железом и никелем. Не происходит также их легирование ионами никеля. Найдено, что дзета-потенциал частиц осадков ферригидрита при рН < 5.4 имеет положительное значение, а при рН > 5.4 становится отрицательным. Точка нулевого заряда частиц осадков соответствует рН 5.4.

Vanadyl formate monohydrate VO(HCOO)2 center dot H2O has been synthesized by a facile two-stage method. The chemical and structural identity of the synthesized compound has been confirmed by X-ray diffraction, ther-mogravimetry, vibrational and absorption spectroscopy. It was established that during heating in water and ethylene glycol, VO(HCOO)2 center dot H2O leads to vanadyl hydroxide VO(OH)2 and vanadyl glycolate VO(OCH2CH2O) being formed. When heated in air or in helium at 300 degrees C and higher, VO(HCOO)2 center dot H2O transforms into vanadium pentoxide or sesquioxide, respectively. VO(HCOO)2 center dot H2O was used as a precursor for the synthesis of nanoscale vanadium sesquioxide (with an average particle size of 50 nm), which is stable under the normal conditions and is characterized by a lower metal-insulator transition temperature than the microsized (bulk) compound. The effect of transition temperature reduction for nanoscale vanadium sesquioxide agrees with the lower value of its unit cell volume (V = 296.74 angstrom 3) as compared with that for bulk V2O3 (297.7 angstrom 3). The main factor affecting the V2O3 particle size is the annealing temperature of precursor in inert atmosphere.

A new series of BaRE6(Ge2O7)2(Ge3O10) (RE = Tm, Yb, Lu) germanates and activated phases BaYb6(Ge2O7)2(Ge3O10):xTm3+ and BaLu6(Ge2O7)2(Ge3O10):12yYb3+,yTm3+ have been prepared using a solid-state reaction. An XRPD study has revealed that the compounds crystallize in the monoclinic system (space group P21/m, Z = 2). The crystal lattice consists of zigzag chains of edge-sharing distorted REO6 octahedra, bowed trigermanate [Ge3O10] units, [Ge2O7] groups, and eight-coordinated Ba atoms. The density functional theory calculations have confirmed a high thermodynamic stability of the synthesized solid solutions. According to the results of vibrational spectroscopy studies and diffuse reflectance measurements, the BaRE6(Ge2O7)2(Ge3O10) germanates are promising compounds for the creation of efficient lanthanide ion activated phosphors. Under 980 nm laser diode excitation, the BaYb6(Ge2O7)2(Ge3O10):xTm3+ and BaLu6(Ge2O7)2(Ge3O10):12yYb3+,yTm3+ samples exhibit upconversion luminescence corresponding to the characteristic 1G4 → 3H6 (455-500 nm), 1G4 → 3F4 (645-673 nm) and 3H4 → 3H6 (750-850 nm) transitions in Tm3+ ions. Heating of the BaLu6(Ge2O7)2(Ge3O10):12yYb3+,yTm3+ phosphor with the optimal composition up to 498 K leads to the enhancement of a broad band at 673-730 nm, caused by 3F2,3 → 3H6 transitions. It has been revealed that the fluorescence intensity ratio between this band and the band at 750-850 nm may be used for temperature sensing. The absolute and relative sensitivities in the studied temperature range reach 0.021% K-1 and 1.94% K-1, respectively.