The development of multi-doped oxides based on the La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3-delta (LSCF) and La1-xSrxMnO3+delta 1-x Sr x MnO 3+delta perovskites would help to achieve the improved electrochemical activity of air electrodes in protonic ceramic cells due to the formation of the single-phase triple-conducting material. The search for prospective medium-entropy and high-entropy oxides based on (La,Sr)(Co,Fe,Mn)O3-delta 3-delta could provide the electrode material with advanced hydration ability. In the present work, the formation and stability of new La 0.6 Sr 0.4 Co x Fe 1-x-y Mn y O 3-delta phases are estimated by thermodynamic calculations and the structure factors. Experimentally obtained La 0.6 Sr 0.4 Co x Fe 1-x-y Mn y O 3-delta powder samples are characterized by X-ray and neutron powder diffraction. The refined crystal structure parameters of the medium-entropy single-phase La 0.6 Sr 0.4 Co 0.33 Fe 0.33 Mn 0.33 O 3-delta (LSCFM333) oxide with the trigonal structure (space group R 3 c ) and the cell parameters of a = 5.4642(1) & Aring; and c = 13.284(4) & Aring; in hexagonal axes are used to design of a supercell simulation for density functional theory (DFT) calculations. The first-principles results are proposed to evaluate the thermodynamic parameters of proton uptake to assess future applications of Mn-doped LSCF in proton-conducting ceramic cells. The calculated values of the hydration enthalpy Delta H hydr for the LSCF and LSCFM333 derivatives are equal to 4.5 kJ mol-1- 1 and - 3.5 kJ mol-1,- 1 , respectively, which are supported by the thermogravimetric analysis (TGA). The present study shows that the modeling techniques, including the thermodynamic and DFT calculations, can be successfully applied to the design of the related oxide materials for applications in solid oxide cells.

Bayesian analysis has been applied to polarized neutron reflectivity data. Reflectivity data from a magnetic TbCo thin-film structure were studied using a combination of a Monte Carlo Markov-chain algorithm, likelihood estimation and error modeling. By utilizing Bayesian analysis, it was possible to investigate the uniqueness of the solution beyond reconstructing the magnetic and structure parameters. The expedience of this approach has been demonstrated, as several probable reconstructions were found (the multimodality case) concerning the isotopic composition of the surface cover layer. Such multimodal reconstruction emphasizes the importance of rigorous data analysis instead of the direct data fitting approach, especially in the case of poor statistically conditioned data typical for neutron reflectivity experiments. This article presents details of the analysis and a discussion of multimodality.

During irradiation of dispersion U–Mo/Al fuel, along with the formation of the (U,Mo)Al x interaction layer, the formation of pores containing gaseous fission products also takes place. Gas pores are formed in the fuel particles, in the (U,Mo)Al x layer and in the aluminum matrix near the (U,Mo)Al x layer. Usually, the structure of pores is analyzed using optical and scanning electron microscopy, which makes it possible to study only very large pores, those with sizes from tenths of a micron or more. In the present paper, the effect of burnup and isochronous annealing in the 150–580°C temperature range on the change in the substructural characteristics of dispersion U–Mo/Al fuel is established. The values of the characteristics are determined on the basis of experimental data on small-angle neutron scattering. This made it possible to study the substructural characteristics of the fuel in the range of 1 to 50 nanometers.

LiNi1 – xCoxPO4 (x = 0.3, 0.5, 0.7) compounds have the olivine structure, space group Pnma, with 3d transition metal ions in the 4c octahedral position. The structural analysis of polycrystalline LiNi1 – xCoxPO4 (x = 0.3, 0.5, 0.7) samples is carried out by elastic neutron scattering, and variants of the mutual distribution of nickel and cobalt ions in the 4c position are studied in detail. For the LiNi0.5Co0.5PO4 compound, six options for the mutual distribution of nickel and cobalt ions are proposed. The best description of the neutron-diffraction patterns for the compounds with x = 0.5 is obtained for two models of the distribution of Ni and Co ions in the sequence: Ni–Co–Ni–Co and Co–Ni–Co–Ni, respectively. Nickel ions form planes in the LiNi0.5Co0.5PO4 sample, parallel to ab and alternating with cobalt planes. To describe the neutron-diffraction patterns of x = 0.3 and x = 0.7 compounds, four variants of models for the mutual distribution of Ni and Co ions in the 4c position are proposed. The four versions of the models considered lead to additional structural reflections that are absent in the experimental neutron-diffraction patterns. The experimental neutron-diffraction patterns of the LiNi0.7Co0.3PO4 and LiNi0.3Co0.7PO4 compounds can best be described using the equiprobable distribution of 3d transition-metal ions.

The neutron diffraction, magnetic and heat capacity measurements have been carried out to study the polycrystalline sample LiNi0.5Co0.5PO4 prepared by the glycerol-nitrate synthesis method. Models of Ni- and Co-ion occupation the 4c octahedral position in a crystal structure LiNi0.5Co0.5PO4 are calculated for a paramagnetic state. The best model is the Ni- and Co-ions occupy the 4c site in Pnma patent space-group in sequence Ni–Co–Ni–Co or Co–Ni–Co–Ni. It is shown that nickel ions form ab planes alternating with the planes of cobalt ions in the direction of the c crystallographic axis. At 7 K, an average magnetic moment of 3d-ions is equal to 1.90 (9) μ B. The moments are ordering antiferromagnetically and parallel to the bc plane decreasing to zero at 15 K. In the high-spin state a temperature dependence of the Ni2+/Co2+ ion-magnetic moment is well described within the 2D Ising model with order parameter β = 0.198 and Néel temperature T N = 14.1 (1) K, obtained from heat capacity data. This temperature agrees well with T cr = 14.3 (2) K, determined with magnetic measurement. Maybe the short-range magnetic order exists in LiNi0.5Co0.5PO4 over temperature region (14–16) K, that is confirmed by the maximum on a temperature dependence of the magnetization at 16.1 (5) K.

The LiNiPO 4 , LiNi 0.9 Mn 0.1 PO 4 , and LiNi 0.9 Co 0.1 PO 4 single crystals are studied with heat capacity and neutron diffraction measurements over the temperature interval (10–30) K. Two peaks are observed on the temperature dependence of heat capacity for LiNiPO 4 , and LiNi 0.9 Co 0.1 PO 4 samples. One peak indicates the first order phase transition from an antiferromagnetic commensurate (C) structure to an incommensurate (IC) one upon heating. According to neutron diffraction, in LiNiPO 4 the IC ordering is described by the propagation vector k = 2 π / b (0, 0.080, 0) at the Néel temperature T N = 20.8 K, and k = 2 π / b (0, 0.098, 0) at T N = 20.2(1) K for LiNi 0.9 Co 0.1 PO 4 . A further increase in temperature leads to the second order phase transition to a paramagnetic state at critical temperature T IC = 21.7 K and 21.1 K for LiNiPO 4 and LiNi 0.9 Co 0.1 PO 4 , respectively. The C and IC phases coexist over the temperature interval (20.6–20.8) K and (20.2–21.2) K in LiNiPO 4 and LiNi 0.9 Co 0.1 PO 4 , respectively. In the LiNi 0.9 Mn 0.1 PO 4 the magnetic phase transition occurs at T N = 22.7 K, but a magnetic scattering is observed up to 24.6 K.

Sr2Ni1-xMgxMoO6 double perovskites were synthesized by pyrolysis of glycerol-salt mixtures and their vibrational phonon modes were investigated using optical spectroscopic techniques. X-ray diffraction and Raman spectroscopy were employed to investigate crystal structures of these perovskite materials and purity of the samples. The magnetic ground state of Sr2Ni1-xMgxMoO6 has been characterized using magnetic susceptibility measurements indicating that Sr2Ni0.75Mg0.25MoO6 orders in an antiferromagnetic state at about 56K while Sr2Ni0.5Mg0.5MoO6 and Sr2Ni0.25Mg0.75MoO6 are paramagnetic.

The real structures of α-Al2O3 – δ anion-deficient corundum crystals characterized by a nonstoichiometry level of δ ~ 0.001, which are applied in X-ray, gamma and beta dosimetry, are neutronographically investigated for the first time. Neutron-scattering measurements are performed on two crystals sintered by the Stepanov method; the anion-vacancy contents are Ca = 8 × 1016 cm–3 for the radiation-sensitive crystal and Ca < 1014 cm–3 for the crystal taken after annealing in an oxygen atmosphere and not sensitive to radiation. With pronounced indications of significant fragmentedness revealed from attestation of these two crystals, in both cases the corundum structure is recognized, and the lattice parameters and atomic coordinates were found. Three approaches are considered for processing the neutron-scattering data obtained from the crystal with the smallest oxygen deficiency (Ca < 1014 cm–3), with the measured intensities corrected in different ways. The best results, which are numerically identical within the framework of the three considered approaches, are extracted from the “ideal crystal” model. The obtained results are verified for the structure characterized by Ca = 8 × 1016 cm–3.

Pressure leaching is one of the most high-demanded and promising hydrometallurgical technology, which allows one to obtain high efficiency. Taking into account the shutdown of zinc plant in Vladikavkaz («Electrozinc, Lls.») searching the modern methods of zinc production is of current interest. In this work, the issue was observed on influence of temperature and sodium lignosulfonate (SL) onto the zinc and iron sulfides behavior during pressure leaching of zinc sulfide concentrate from the Uchalinsk deposit. Temperature increasing from 130 to 150o C led to decreasing of zinc extraction and sulfur-sulfide pellets formation; that indicated increasing the zinc sulfide wettability by the molten sulfur due to reduction of viscosity and surface tension of molten sulfur. Increasing the LSN dosage promoted running up of the absolute value of the zinc extraction. The highest growth of the zinc extraction (17.39 %) was obtained at 0.2 g/dm3 LSN. Further increasing of the LSN concentration on 0.2 g/dm3 (up to 0.4, 0.6, 0.8 g/dm3 ) led to double decrease of their effectiveness in reference to previous LSN concentration.

Spontaneous and magnetic field induced incommensurate - commensurate magnetic phase transitions have been studied in Tb1-xErxNi5 compounds near the critical concentration x(c) = 0.125. Compounds crystallize in the hexagonal CaCu5 type phase (P6/mmm space group). In compounds with x >= x(c) the magnetic order is a commensurate ferromagnetic one. The samples with x < x(c) have an incommensurate structure that is a fan like magnetic structure and described by two propagation vectors. An incommensurate - "lock in" magnetic transition takes place at 10 K at cooling regime.

Magnetic and neutron powder diffraction measurements have been carried out on Tb0.9Er0.1Ni5 intermetallic compound. The intermetallide crystallizes in the hexagonal CaCu5-type structure and possesses a long-range magnetic order at temperatures below 22 K. A fan-like magnetic structure is described by two propagation vectors: k(1) = 0 and k(2) = 2 pi/c(0, 0, 0.036), at 20 K. The total Tb-ion magnetic moment has the ferromagnetic and modulated components. The latter is a transverse spin wave. When the sample is cooled at a temperature below 8 K, the module of the k(2) vector does not change and is equal to k(2) = 2 pi/c(0, 0, 0.027). An "in-commensurate - lock-in" magnetic transition takes place at 8 K. The k(2) vector exhibits a temperature hysteresis of about (5-6) K, whereas the intensities of Bragg reflections and satellites do not show up appreciable changes. When an external magnetic field is applied to the sample, the satellites and the module of the k(2) vector decrease, while the Bragg intensities increase. The sample becomes a ferromagnetic at a field of similar to 2 kOe, and the Tb-ion magnetic moment is equal to 8.3 mu(B). A general notion of the Tb0.9Er0.1Ni5 magnetic state evolution with an external field is given using the field dependence of the background intensity in diffraction patterns. First principle calculations for TbNi5 and Tb0.9Er0.1Ni5 are performed including the 4f states into the orbital basis and accounting for strong electronic correlations and spin-orbital coupling. This allowed obtaining both spin and orbital moments of the effective Tb-ion moment and estimating also the value of Tb-Tb exchange interaction.

Lithium orthophosphates of the LiMPO4 type (M = Ni, Co, Fe, and Mn) gain intensive development due to the potential applications as electrodes for lithium-ion batteries. The other remarkable property of LiMPO4 is the multiferroicity. We present a study of the crystal structure and magnetic properties, refined anisotropic thermal coefficients and Li-ion migration maps of the LiNi0.9M0.1PO4(M = Co, Mn) single crystals and compared results for the undoped LiNiPO4 and LiMnPO4 ones. All samples have been synthesized by the flux method. In LiNi0.9M0.1PO4(M = Co, Mn), doping increases the lattice constants, unit cell volume, valence bonds, and the anisotropic thermal coefficients. By means of X-ray diffraction and the program package TOPOS, the Li-cation migration maps were obtained. The Li-ions move along the [010] direction which can be clearly visualized in the mixed-metal LiNi0.9 M0.1PO4(M = Co, Mn) single crystals. It was found that the 10% doping of LiNiPO4 by cobalt ions leads to a decrease in the formation temperature and to the suppression of the incommensurate phase. The 10% doping of manganese ions increases the transition temperature, while the temperature range of the incommensurate phase narrows. (C) 2018 Elsevier B.V. All rights reserved.

We present the magnetic properties of LiNi1-xCoxPO4 magnetoelectrics, with x = (0–0.2), and their analysis of concentration dependences. Samples have been synthesized by a glycerol-nitrate method. To refine crystal structure X-ray diffraction measurements were carried out. Magnetic measurements were performed at the external magnetic field of 500 Oe over the temperature range (2–300) K. The neutron powder diffraction patterns of LiNi0.9Co0.1PO4 were recorded over temperature interval from 4.4 K up to 25 K. The partial doping in the LiNi1-xCoxPO4 magnetoelectrics the Ni ions for Co ions leads to a narrowing of the temperature interval where the incommensurate phase is established.

Sr2Ni1-xMgxMoO6 (x = 0.25 and 0.5) double perovskites were synthesized by pyrolysis of glycerol–salt mixtures and their magnetic properties were investigated. X-ray diffraction was employed to refine crystal structures of these perovskite materials and set sample purity degree. The magnetic ground state of Sr2Ni1-xMgxMoO6 (x = 0.25 and 0.5) has been characterized using magnetic susceptibility measurements. They indicate that Sr2Ni0.75Mg0.25MoO6 is ordered in an antiferromagnetic state below 56 K while Sr2Ni0.5Mg0.5MoO6 is paramagnetic.

AbstractThe magnetic structures that form in La_1– x R_ x Mn_2Si_2 ( R = Sm, Tb) layered compounds with various concentrations x have been determined by magnetic neutron diffraction and magnetic measurements, and the magnetic phase diagrams have been built. It is shown that the formation of the magnetic structures is dependent not only on exchange interactions, but also on the type of the magnetic anisotropy of a rare-earth atom. It is found that, in La_1– x Tb_ x Mn_2Si_2 compounds with 0.2 < x < 0.5, the competition of the Tb–Mn and Mn–Mn interlayer exchange interactions and the existence of a strong uniaxial magnetic anisotropy in the Mn and Tb sublattices leads to the frustrated magnetic state and prevents the formation of the long-range magnetic order in the Tb sublattice.

Physical quantities affecting the magnitude of magnetocaloric effect in ferro- and ferrimagnetic materials with first and second order magnetic phase transitions are considered. Governing equations for the main characteristics of the magnetocaloric effect are given and analyzed. Their outcomes are compared with the experimental results.

Elastic modulus and hardness, X-ray and neutron diffraction, small-angle scattering and neutron tomography have been used to study bone samples of healthy people and those suffering from osteoporosis. The samples under studied belonged to people of different ages: a child, middle and elderly. The crystalline structure of the mineral part of the bone is typical of hydroxylapatite. The overatomic structure presents particles of two characteristic sizes: small (3–4) nm and large (30–40) nm. The size of large particles decreases significantly in the case of osteoporosis bone. It is established that the structure changes with age. The unit cell of osteoporosis bone is less than that of healthy one.

Here novel photocatalysts, SnO2/CuO and CuO/SnO2 nanocomposites were successfully synthesized by chemical method at room temperature. X-ray Diffraction (XRD), transmission electron microscopy (TEM), Fourier transform Infrared (FT-IR), UV–Visible (UV–Vis) and photoluminescence (PL) spectroscopy were utilized for characterization of the nanocomposites. The photocatalytic activity of the nanocomposites was investigated. The hybrid nanocomposites exhibited high photocatalytic activity as evident from the degradation of methylene blue (MB) dye. The result revealed substantial degradation of the MB dye (92 and 69.5% degradation of SnO2/CuO and CuO/SnO2, respectively) under visible light illumination with short period of 30 min. Their large conduction band potential difference and the inner electrostatic field formed in the p–n heterojunction provide a strong driving force for the photogenerated electrons to move from Cu2O to SnO2 under visible light illumination. The excellent photodegradation of methylene blue suggested that the heterostructured SnO2/CuO nanocomposite possessed higher charge separation and photodegradation abilities than CuO/SnO2 nanocomposite under visible light irradiation.