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This work discusses the synthesis of magnetite nanoparticles using microfluidic method. The main characteristics of the resulting nanoparticles were investigated, including chemical composition, size distribution, saturation mass magnetization, and coercive force. To assess the possibility of using nanoparticles for medical and biological purposes, the hemolytic activity of a suspension of magnetite nanoparticles was studied. [ABSTRACT FROM AUTHOR]

Terbium orthoferrite (TbFeO3) perovskite demonstrates specific magnetic properties which are object of interest. Aggregated granular nanopowder of TbFeO3 particles of 85.6 nm were obtained by direct solution combustion method. The orthorhombic perovskite structure (space group Pbnm) of the terbium orthoferrite was confirmed by powder X-ray diffraction, Raman spectroscopy and 57Fe Mössbauer spectroscopy. The unusual granular morphology and mesoporous structure of the nanopowder were investigated by scanning electron microscopy and adsorption-structural analysis via low-temperature (77 K) adsorption-desorption of nitrogen with a total porosity of 0.0145 cm³/g and average pore width of 12 nm. The magnetic properties of TbFeO3 nanoparticles were thoughtfully studied, M = 34.2 emu/g at T = 10 K, Hc = 300 Oe. The onset of reorientation of the Fe3+ spin system at T ~ 18 K and the antiferromagnetic ordering of Tb3+ ions at T ~ 4 K were observed by vibrational magnetometry. Obtained results confirm the flexible paramagnetic to antiferromagnetic behavior of granular TbFeO3 nanopowder. Highlight: Granular nanopowder of TbFeO3 was obtain by direct solution combustion method. Aggregated granular morphology of perovskite TbFeO3 was confirmed. Magnetization of TbFeO3 granules is in pronounced dependence of temperature. [ABSTRACT FROM AUTHOR]

Studies of the properties of ZnxFe3 –xO4 (x = 0, 0.25, 0.5, 0.75, 1.0) magnetic nanoparticles synthesized by a modified hydrothermal method are presented in comparison with the properties of the same nanoparticles stabilized with polyacrylic acid ZnxFe3 –xO4@PAA. The structure, size, morphology, and magnetic properties of the samples were studied by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT IR), physical properties measurements (PPMS), and Mössbauer spectroscopy. The synthesized nanoparticles are single-phase, without additional impurities, have a narrow size distribution and are in the superparamagnetic phase. From the (XRD) measurements, it was found that with an increase in the Zn content from x = 0 to x = 1.0, the sizes of the nanoparticles were increasing from 17 to 33 nm. Analysis of the Mössbauer spectroscopy data showed that when doped with Zn ions from x = 0 to x =1.0, the sizes of the nanoparticles were decreasing from 15 to 5 nm. The results of the Mössbauer studies showed that both ZnxFe3 –xO4 and ZnxFe3 –xO4@PAA has a core/shell type structure in which the core is magnetically ordered, whereas the shell does not have magnetic ordering. Mössbauer studies indicate that the coating of citric acid particles leads to their isolation from each other, reducing or eliminating interactions between particles, reducing the thickness of the paramagnetic shell, and thereby increasing the diameter of the core, which is in a magnetically ordered state. [ABSTRACT FROM AUTHOR]

Virtually unlimited volumes of serpentine resources stimulate search for new procedures for its processing, including those involving thermal activation. Along with the calcination parameters (temperature, time), the crystal-chemical features of the initial serpentines are an important factor. They predetermine the sequence of the formation of new phases in the course of thermolysis and the content of these phases in the heat treatment product. The influence of the calcination temperature on the thermal decomposition of a serpentine mineral, antigorite, was studied by differential scanning calorimetry, X-ray diffraction analysis, and Mössbauer spectroscopy. Amorphous antigorite is not formed in the course of thermolysis, and the intermediate amorphous magnesia–silicate phase is a mixture of two dehydroxylates differing in the ability to react with acid solutions. The activity of the calcination products was determined by two different methods. The optimum calcination temperature is 750°C; it ensures the maximal content of the amorphous active magnesia–silicate phase. [ABSTRACT FROM AUTHOR]

The effect of Fe and Mg-codoping on the crystal structure, optical and dielectric properties of bismuth tantalate-based pyrochlores has been studied. Samples of Bi2MgxFe1−xTa2O9.5−Δ (x ≤ 0.7) are characterized by a porous dendrite-like microstructure. Fe,Mg-codoped bismuth tantalate pyrochlores are thermally stable up to a temperature of 1140 °C (x = 1). The Bi2Mg0.5Fe0.5Ta2O9.5−Δ thermal expansion coefficient increases uniformly and weakly from 3.6 to 9.3 × 10−6 °C−1 (30–1050 °C). The unit cell parameter of solid solutions increases uniformly from 10.5009(1) Å (x = 0.3) up to 10.5225(7) Å (x = 0.7). The structural parameters of disordered pyrochlore are determined by the Rietveld method (sp. gr. Fd 3 ¯ m:2 (227), Z = 8). According to near edge X-ray absorption fine structure and X-ray photoelectron spectroscopy data, ions in solid solutions are in the charge states Bi (+3), Mg (+2), Fe (+3), Ta (+5-δ). The Mössbauer spectrum is represented by a symmetric doublet with parameters IS = 0.365 ± 0.0020 mm/s, QS = 0.604 ± 0.034 mm/s, related to Fe3+ ions in regular axial octahedral positions. The samples exhibit the properties of dielectrics. The permittivity and the tangent of dielectric losses at 20 °C increases with the growth of iron content in the samples in the range of 28.5–30.5 and 0.001 (1 MHz). The width of the band gap of the obtained materials for direct allowed electronic transitions is in the range of 2.16(5)–2.41(5) eV. The studied samples satisfy the condition of efficient conversion of solar energy into an electrical one and are promising as catalysts and light-absorbing elements for solar panels. [ABSTRACT FROM AUTHOR]

The results of the investigation into the morphology and phase and chemical composition of protective films and corrosion products deposits that form spontaneously on the steel surface during operation of the heat-exchange equipment with the oxidizing water chemistry in the tertiary coolant circuit of a BN-800 reactor unit are reported. A comparison is made of the phase composition of protective oxide films on the working surfaces in the tertiary coolant circuit of steam generators at BN-600 and BN-800 reactor units operating with different water chemistries. It has been demonstrated that, unlike type PGV horizontal steam generators employed at power units with pressurized water power reactors, where oxide films and deposits of corrosion products in the secondary circuit are determined only by magnetite (Fe3O4), films and deposits in the N-272 steam generator contain three phases: magnetite (Fe3O4), hematite (α-Fe2O3), and lepidocrocite (γ-FeOOH). A protective oxide film of magnetite (100%) is formed directly on the metal. On the film surface are formed a layer of deposits tightly bound to it and consisting of 70% of magnetite, 25–30% of hematite, 1–5% of lepidocrocite, and loose surface corrosion products deposits of corrosion products. The phase compositions of the dense layer (hematite) and loose corrosion products' deposits (hematite + lepidocrocite) on the working surfaces of the heat-transfer tubes in the N-272 steam generator correspond to the weakly alkaline oxidizing water chemistry for the tertiary circuit of the BN-800 reactor unit. It has been established that, irrespective of the type of water chemistry (oxidizing for the BN-800 reactor or reducing for the BN-600 reactor), an oxide layer of magnetite with protective properties is formed spontaneously on the surface of pearlitic steel during operation. [ABSTRACT FROM AUTHOR]

Measurements of the magnetic moment of a ship are necessary for monitoring safety from magnetic mines and from stealth, by the magnetic field. A modification of the method of measuring the magnetic moment of a ship by using a three-component differential magnetometer is examined. With the aid of computer modeling, a comparison was done of the errors of the method developed by the authors with those of known analogs, and its advantage in precision (by practically one order of magnitude) was established. It is shown that the proposed method can be applied also to magnetic models of ships and standard samples of magnetic materials in order to determine the components of hysteresis loops by magnetization. [ABSTRACT FROM AUTHOR]

For the first time, based on complex research, a zoo technical justification for the use of PS-2 and PS-4 biostimulators in the technology of calf raising in individual boxes and pavilions is given to activate the body's adaptogenesis to cold and implement the productive qualities of young stock during rearing and fattening in typical premises. Intramuscular injection of PS-2 (polysaccharide complex of yeast cells immobilized in an agar gel by adding a benzimidazole derivative) and PS-4 (similar to PS-2 plus antibiotic of the cephalosporin) to calves in a dose of 3 ml at 2-3 and 7-9 days of life stimulates their growth and development during the raising, rearing, and fattening periods, thereby reducing the incidence of diseases. By the end of the growing, rearing, and fattening periods, the animals of the 1st and 2nd experimental groups outnumbered their control peers by 7.2 and 8.2 kg; 11.4 and 13.6 kg; as well as 13.8 and 16.8 kg, respectively (P<0.05-0.01). A similar pattern occurred in the nature of changes in exterior measurements and growth coefficient of animals of the compared groups. At the same time, in the calves of the 1st and 2nd experimental groups, respiratory and digestive diseases were reduced by 2.0 and 4.0 times, the recovery time was decreased by 3.47 and 5.12 days, and the Mellenberg coefficient was reduced by 3.7 and 12.1 times, compared to the control group (P<0.05). It was found that PS-2 and PS-4 increased the pre-slaughter weight of the young stock by 14.6 and 18.0 kg, the weight of the hot carcass by 12.8 and 15.8 kg, and the slaughter weight by 13.7 and 16.5 kg (P<0.05-0.01). Moreover, the weight of the half-carcasses of the young stock of the experimental groups, compared to the control group, was higher by 6.7 and 8.7 kg, the yield of meat by 5.4 and 6.9 kg, and of bones by 0.6 and 1.0 kg (P<0.05-0.001). With an increase in the weight of half-carcasses of the experimental animals, the specific weight of the meat increased, and the bones, on the contrary, decreased. Furthermore, the yield of meat of the highest and first grades in the animals of the experimental groups increased on the background of intramuscular injection of biostimulators when using PS-2 (by 0.6 and 0.3%; P<0.01) and PS-4 (by 0.9 and 1.1%; P<0.01). However, the second grade decreased by 0.9 and 2.0% (P>0.05), compared to the control group. [ABSTRACT FROM AUTHOR]

Nanocrystals of Bim+ 1Fem– 3Ti3O3m+ 3 (m = 4–9) Aurivillius phases were synthesized by thermal decomposition of a coprecipitated mixture of bismuth, iron, and titanium hydroxides. The average crystallite size in nanopowders depends on m and is 50–100 nm. The samples were characterized by simultaneous thermal analysis, elemental analysis, X-ray diffraction, and Mössbauer spectroscopy. It was shown that the onset of Bim+ 1Fem– 3Ti3O3m+ 3 crystallization is near the melting point of the bismuth oxide-based non-autonomous (surface) phase (450°C). The Bim+ 1Fem– 3Ti3O3m+ 3 compounds where m ≤ 5 crystallize in one stage. The compounds where m > 5 are formed in two stages. First, Aurivillius phases with m ≈ 5 and an amorphous phase are formed. Then, the components of the amorphous phase are incorporated into the perovskite-like blocks of the Aurivillius (m ≈ 5) phases, most likely through their outer perovskite-like layers. Then, the components are redistributed between the outer and inner layers of the perovskite-like blocks. The elucidated dependence of the formation mechanism of Bim+ 1Fem– 3Ti3O3m+ 3 nanocrystals on their composition can be used in the technology of directed synthesis of nanocrystalline multiferroics. [ABSTRACT FROM AUTHOR]

BiFeO3 with 50–70 nm crystallites was obtained by glycine–nitrate combustion under varying conditions. These nanopowders demonstrated magnetic ordering at temperatures up to 400 K. The results were compared with the data known from other works, and it was shown that at the sizes lower than 70 nm the predominant contribution to the magnetization belongs to the crystallite surface. The effect of the increased magnetization, associated with the spin cycloid distortion, can also occur which, however, is less essential for crystallites of sizes ∼10 nm. For the first time, it was shown that the value of magnetization can be controlled technologically within several orders. [ABSTRACT FROM AUTHOR]

Nanocrystalline BiFeO3-based powder materials with an average crystallite size near 40 nm have been prepared by solution combustion synthesis from bismuth and iron nitrates using sucrose and tartaric acid as fuel. The materials have been characterized by X-ray diffraction, helium pycnometry, scanning electron microscopy, energy dispersive X-ray microanalysis, and Mössbauer spectroscopy. Magnetometry results demonstrate that the magnetic response of the materials varies over several orders of magnitude, depending on the synthesis procedure. [ABSTRACT FROM AUTHOR]

Gadolinium orthoferrite GdFeO3 nanoparticles were synthesized by co-precipitation of gadolinium and iron(m) hydroxides in a free impinging-jets microreactor followed by thermal treatment of co-precipitation products. According to X-ray diffraction, the co-precipitated hydroxides were X-ray amorphous, and the content of key elements within their composition corresponded to the stoichiometry of GdFeO3. Powder X-ray diffraction of the product of thermal treatment of hydroxides at 750 °C for 4 h indicated on the formation of GdFeO3 nanocrystals with a perovskite-like orthorhombic structure and an average crystallite size of 27±3 nm. Scanning electron microscopy showed that the gadolinium orthoferrite nanocrystals had an isometric morphology, and their specific surface area was determined by the Brunauer—Emmett—Teller method to be 13.55 m2g−1. Mössbauer spectroscopy and vibrational magnetometry showed that the obtained GdFeO3 nanoparticles were superparamagnetic and were characterized by a bimodal distribution of the effective field, indicating on their core—shell-type composite structure. The study of the composition, structure, morphology, and magnetic behavior of the obtained gadolinium orthoferrite nanoparticles showed that they can be used as a basis for contrast agents for magnetic resonance imaging (MRI). [ABSTRACT FROM AUTHOR]

Layered perovskite-like oxides Bi5–xCaxFeTi3O15–δ with the structure of the four-layer Aurivillius phase were synthesized in the Bi2O3–CaO–TiO2–Fe2O3 system by the solid-state reaction method. The features of the formation and thermal behavior of the solid solution synthesized were studied. [ABSTRACT FROM AUTHOR]

The features of the formation of nanocrystals in the BiFeO3–CaFeO3 system via glycine-nitrate combustion were studied. The crystallite size of the bismuth orthoferrite-based solid solutions (20–45 nm), as well as their particle size, were found to depend on the calcium content. The formation processes were activated in the temperature range corresponding to the melting of the surface (nonautonomous) phase. [ABSTRACT FROM AUTHOR]

The phase composition, the structure of cores and shells, and the dependences of the shell thickness on the fabrication technique were determined by Mössbauer spectroscopy for core/shell Fe3O4/γ-Fe2O3 magnetic nanoparticles (MNPs) with Fe3O4 cores of a fixed size (8 nm) and γ-Fe2O3 shells of a varying thickness (1, 3, or 5 nm). A layer on the MNP surface with a magnetic state differing from that in the bulk was found. It was also found that a spin-glass state probably exists between the core and the shell. The studied core/shell Fe3O4/γ-Fe2O3 MNPs have promising applications in various fields (e.g., biomedicine). [ABSTRACT FROM AUTHOR]

A new type of a promising glassy-crystalline host material was prepared by ultradisperse synthesis in model experiments. The starting product is the nitric acid fraction of fission products (Cs, Sr, Ba), obtained radiochemically from irradiated nuclear fuel of a WWER-1000 reactor (1000-MWel water-cooled water-moderated energy reactor). Equivalent amounts of La(NO3)3, H3PO4, and Fe2O3 are added, and water is removed on heating. After complete removal of moisture, the residue is calcined at 600°С. The phosphated calcinate is dispersed in acetone to obtain slurry and, after removing acetone, converted to the glassy form at 950°С by self-igniting high-temperature synthesis. The whole process of preparing the composite is performed in one container crucible, which is then sealed. The major constituent of the host material is iron (pyro)phosphate glass (~55%); the finely grained crystalline phase, according to X-ray diffraction data, consists mainly of monazite of the composition La2(Sr,Ba)3(PO4)4. The monazite content is about 40%. Monazite forms with the glass via covalent bonding a composite exhibiting high corrosion resistance. The steady-state rate of Cs leaching form the monazite glass is 0.1 μg cm-2 day-1 (90°С, 100 days). [ABSTRACT FROM AUTHOR]

Iron nanowires (NWs) were obtained by template synthesis using polymer track membranes in the framework of development of a general method for the synthesis of regular metal nanostructures. The surface topography of NWs was studied by scanning electron microscopy, and the local state of iron atoms was determined by Mössbauer spectrometry. [ABSTRACT FROM AUTHOR]

Compounds of the formula Bi1-x SrxFeO3-δ with a perovskite structure are prepared by the solid-phase synthesis at the oxygen partial pressure p = 1 atm and studied. An analysis of the experimental data obtained using Mössbauer spectroscopy and X-ray diffractometry allows us to make the inferences regarding the structure of the samples under investigation and the charge state and symmetry of the local environment of iron atoms. [ABSTRACT FROM AUTHOR]

The mechanism of formation of the perovskite-like layered structure of the oxide Gd2SrFe2O7 was studied. The limiting stages are those of formation of phases with perovskite (GdFeO3, SrFeO3− x ) and K2NiF4 (GdSrFeO4) structures. The Mössbauer study has shown that iron atoms exist in a heterovalent state (Fe3+ and Fe4+) only in the structure of SrFeO3− x ). [ABSTRACT FROM AUTHOR]

A series of tellurides FexTi1− x Te1.65 ( x = 0, 0.1, 0.2 ..., 1.0) synthesized at 850°C were studied by X-ray phase and X-ray fluorescent analysis and Møssbauer spectroscopy on 57Fe. In this series two solid solutions are formed: phases I and II with homogeneity regions within the limits of 0 ≤ x ≤ 0.3 and 0.9 ≤ x ≤ 1.0, respectively. Iron in this series exists in two various states: Fe2+ sym and Fe2+ asym as differentiated from the series of tellurides FexTi1− x Te1.45 where three states of iron Fe2+ sym, Fe2+ asym, and Fe0 were found. On passing from FexTi1− x Te1.45 to FexTi1− x Te1.65 the number of formed phases decreases, and phase relations become simpler. The absence of Fe0 from phase I of tellurides FexTi1− x Te1.65 can point to the fact that TiTe1.45 and TiTe1.65 belong to different homogeneity regions. [ABSTRACT FROM AUTHOR]

The values of the gross (net) heating value were determined by burning samples of liquid biofuels-rapeseed and soy oils-and rapeseed oil fatty acid methyl esters manufactured in Germany and in Ukraine were determined. The experimental data obtained confirm the theoretical calculations that high erucic oil and its derivatives have the highest energy potential. [ABSTRACT FROM AUTHOR]

Unique experimental data on the high heat value of biofuels-soy and rapeseed oils and methyl esters of the latter-which are in good agreement with the data of domestic and foreign researchers confirm the results of calculations: high erucic oil and its derivatives have a higher energy potential than low erucic oil. These data allow determining the indicator and effective indexes of operation of diesel (multifuel) engines with a high degree of reliability. [ABSTRACT FROM AUTHOR]

The multipurpose spectrometer for nondestructive, depth selective investigation of physical and chemical properties of a surface and bulk is described. It realizes opportunities of Mössbauer and X-ray Fluorescence Spectroscopy in normal and TER-conditions, Mössbauer and X-ray diffractometry and also Mössbauer and X-ray Reflectometry. Some analytical characteristics and capabilities of a spectrometer are illustrated as an example of research with a model sample. [ABSTRACT FROM AUTHOR]

In this work the synthesis, powder XRD and Mössbauer studies of the quasibinary system FeTe1.45–TiTe1.45 were carried out. A series of nonstoichiometric tellurides FexTi1-xTe1.45 (x=0.1,0.2,…,1.0) was synthesized by the direct reaction from elements at 850°C. The Mössbauer results are in the good accordance with the XRD data. Behaviors lattice parameters and 57Fe Mössbauer parameters from composition of the tellurides allow to make some conclusions about their compensation mechanism for nonstoichiometry (CMN). For both FexTi1-xTe1.45, and nonstoichiometric Ti3Te4 CMN comes from the formation of Te–Te bonds at the constant metal valence. On the whole, in system titanium-tellurium CMN could be different and depends on the interval of composition. [ABSTRACT FROM AUTHOR]