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In situ high-pressure diffraction experiments on single-crystal α-quartz under quasi-hydrostatic conditions up to 19 GPa were performed with diamond-anvil cells. Isotropic pressures were calibrated through the ruby-luminescence technique. A 4:1 methanol-ethanol mixture and the densified noble gases helium and neon were used as pressure media. The compression data revealed no significant influence of the pressure medium at room temperature on the high-pressure behavior of α-quartz. In order to describe its compressibility for use as a pressure standard, a fourth-order Birch-Murnaghan equation of state (EoS) with parameters KT0 = 37.0 (3) GPa, KT0′ = 6.7 (2) and KT0′′ = −0.73 (8) GPa−1 was applied to fit the data set of 99 individual data points. The fit of the axial compressibilities yields MT0 = 104.5 (8) GPa, MT0′ = 13.7 (4), MT0′′ = −1.04 (11) GPa−1 ( a axis) and MT0 = 141 (3) GPa, MT0′ = 21 (2), MT0′′ = 8.4 (6) GPa−1 ( c axis), confirming the previously reported anisotropy. Assuming an estimated standard deviation of 0.0001% in the quartz volume, an uncertainty of 0.013 GPa can be expected using the new set of EoS parameters to determine the pressure. [ABSTRACT FROM AUTHOR]

• Differential compression of Golay encoded ultrasound (DCGEU) imaging method is proposed. • Feasibility of slow blood flow imaging in small vessels with the DCGEU is demonstrated. • Complementary Golay coded sequences (CGCS) significantly improves the slow flow imaging. • Transducer bandwidth and high receiving channel noise level influence the slow flow imaging. In our research we present a new method of differential compression of the Golay encoded ultrasound (DCGEU) in the standard beamforming mode to visualize the slow (<1cm/s) blood mimicking fluid flow in small diameter tubes. The proposed DCGEU method is based on synthesis of several subsequent B-mode frames acquired with certain time intervals (30 ms in this study) followed by the visualization of differential beamformed radio frequency (RF) echoes, which yielded the images of the scatterers moving slowly in the vessel and suppressing the static echoes outside the vessel. In order to extract small backscattered echoes from the vessel area we took an advantage of improved sensitivity of the complementary Golay coded sequences (CGCS). The validation of the proposed DCGEU method was carried out in two stages. In the first one, we compared the flow images in small tubes with a diameter of 1 mm and 2.5 mm, reconstructed from numerically simulated acoustic data for the standard transmission of short pulses and 16-bits long CGCS signals. In the second stage of the research, the experimental data were acquired in a flow phantom with silicone tubes with an internal diameter of 1.5 mm and 4.5 mm and a fluid flow velocity of 0.9 cm/s. The experiments were carried out using preprogrammed Verasonics Vantage™ research ultrasound system equipped with ALT L12-5/50 mm MHz linear array transducer with 7.8 MHz center frequency. It was evidenced both in simulations and experiments that the DCGEU provided a good flow image along the entire length of tubing with virtually angle independent detection in comparison with the conventional short pulse interrogation. [ABSTRACT FROM AUTHOR]

Abstract: Samples with nominal composition LiM 0.5Mn1.5O4 (M = Fe, Co) were synthesized via a sol–gel process with a post thermal treatment at 1000 °C. In contrast to the Ni-analogue Co- and Fe-doped samples show a fast degradation at 55 °C with an average capacity retention at RT of ∼55% for the Co- and of ∼59% for the Fe-substituted samples, respectively after 70 cycles for a C/2 rate. The PITT plots of the Fe doped spinel exhibited a sharp peak in the discharge capacity when cycled with a cut-off current rate C/5, which was assumed due to a kinetic limitation, which disappears when cycled at slower charge–discharge rates. This assumption was checked, and the mechanisms of Li-intercalation/-de-intercalation were investigated in detail for the Fe and Co doped spinels by in situ synchrotron diffraction. The charge–discharge processes take place through a solid-solution mechanism in both cases, though the Fe-doped spinel exhibits a two-phase region during the discharge. [Copyright &y& Elsevier]

Abstract: The potential use of a double B mixed-perovskite as a promising cathode material in intermediate temperature solid oxide fuel cells (IT-SOFCs) has been anticipated as a result of this work. A thorough investigation of some important parameters like thermal stability, thermal expansion, oxygen non-stoichiometry, electrical conductivity and diffusion characteristics of the PrNi0.6Fe0.4O3−δ ceramic sample have been investigated as functions of temperature (20–1000°C) and oxygen partial pressure (0.6–21,000Pa). According to the measurements, the composition was phase stable at pO2 >1Pa up to 1000°C and shows p-type semiconductivity with a low conductivity versus pO2 dependence. The perovskite has been found to have comparable thermal expansion coefficients with those of commonly used solid electrolytes like CeO2 and ZrO2 based oxides. In case of the chemical diffusion experiments higher oxygen diffusion mobility observed during reduction processes in comparison with those during oxidation have been explained by the already known formation of neutral defect clusters. [Copyright &y& Elsevier]

Abstract: Mixed chromium–rhenium oxides, Cr x Re1− x O2 with 0.31⩽x⩽0.66, have been synthesized for the first time by high-pressure high-temperature synthesis and in evacuated quartz tubes. The crystal structures of the compounds have been determined by single crystal and powder X-ray diffraction. Depending on synthesis conditions (pressure and temperature) these phases crystallize either in a tetragonal structure (P42/mnm) with statistical distribution of metal ions on one site (rutile-type), with cation ordering along c-axis (trirutile-type), or in a monoclinic rutile-like structure (C2/m) with ordering of Cr- and Re-cations and metallic Re–Re bonds. The “a” parameter of the tetragonal unit cell increases with increasing Re content whereas the “c” parameter decreases, indicating a strengthening of the Re–Re bond. The thermal stability of tetragonal Cr x Re1− x O2 in Ar-atmosphere depends on the Re-content, decomposition is observed at 1241K for x=0.34, but already at 966K for x=0.5. The thermal expansion of Cr x Re1− x O2 is anisotropic with a larger expansion coefficient in the “c” direction. Tetragonal Cr x Re1− x O2 with 0.31⩽x<0.54 order antiferromagnetically at low temperatures with T N depending on the Cr-content x. [Copyright &y& Elsevier]

It’s common knowledge that heavy metal (HM) can enter the soil together with fertilizers which contaminates agricultural landscapes. The purpose of the research is to study influence of fertilizers on accumulation and migration of Cd, Pb ,Zn, Cu, Co, Mn in soil and plants. The research was conducted during field experiments in chernozem (blacksoil). We studied two levels of plant fertilizing: the first one without fertilizers and the second one with fertilizing of norms of NPK. The fertilizers were distributed in the following way: spring wheat (Triticum vulgare) – N60P60K60; spring barley (Hordeum vulgare) and oats (Avena sativa) – N45P45K20; millet (Panicum miliaceum) – N30P40K40; peas (Pisum sativum) – N10P60K60; buckwheat (Fagopyrum esculentum) – N45P60K60.v We found out that fertilizing raises the amount of Сd, Рb Zn, Сu, Со and Мn on 10-36% in soil and increases mobility of Zn, Си, Со and Мn on 25%. The increase of fertilizing of spring wheat, barley, oats, millet and buckwheat reduces whole volume of HM migration in phyto mass on 5-30%. But it also stimulates Pb migration in the plants of spring wheat, migration of Сd, Zn and Сu into bio mass of oats and barley, and migration of Cd and Mn into peas. The main portion of accumulated elements is stored in a root system of a plant, Zn and Cu are able to transport into inflorescence. The volume of HM accumulation in phyto mass of fertilized plants doesn’t exceed TLV.

While cultivating crops on sloping lands it’s necessary to know the level of land relief influence on plant productivity. The purpose of research is to study the effects of different types of slopes on distribution of snow, water reserves in soil and productivity of spring soft wheat and barley. The trials were carried during 2012-2014 years on the lands of SBEI “Aksenovsky Agricultural Technical School”, located on the southern part of Bugulmino-Beleevskaya Hill. The research focused on the north-east, east, south-east, southern and western slopes. The soil of the slopes is leached chernozem (blacksoil). The trials showed that on any sloping lands the greatest amount of snow gathered in the lower part of the slope. It allows accumulating about 11,6-194,3 mm of atmospheric moisture and storing 157-211 mm of water in the upper soil layer (0-0,7m), which is on 35,3-43,3% more than in the upper part of Bugulmino-Beleevskaya Hill. If we plant spring soft wheat in the lower part of the Hill, we’ll obtain the yield of 1,84 – 2,12 t/ha of wheat and 1,80 – 2,27 t/ha of barley. It’s in average on 3,4-29,6% more than the productivity of crops planted in the middle part of the hill and in 1,2-2,1 times more than the productivity of the crops planted in the upper part of the slopes. It’s more appropriate to plant spring wheat on the western slopes and barley on the south-east and northern slopes, if you want to obtain maximum yield of them.

Temperature dependent synchrotron x-ray powder diffraction, differential scanning calorimetry, and magnetic measurements were performed on Ni2+xMn1-xGa (x=0.20 and 0.35) magnetic shape memory alloys. For x=0.20, though the monoclinic phase is thermodynamically stable, a trace of residual stress can stabilize a tetragonal phase. The residual-stress-induced tetragonal phase transforms to the cubic austenite phase over an unusually large temperature range (348 K≤T≤693 K), suggesting extremely slow kinetics of transformation. In contrast to x=0.20, the thermodynamically stable phase of x=0.35 is tetragonal and this composition exhibits the usual features of a reversible martensitic transformation. The results suggest that for x=0.20 the monoclinic and tetragonal phases are nearly degenerate. [ABSTRACT FROM AUTHOR]

We report crystal structure, electronic structure, and magnetism of manganese tetraboride, MnB4, synthesized under high-pressure, high-temperature conditions. In contrast to superconducting FeB4 and metallic CrB4, which are both orthorhombic, MnB4 features a monoclinic crystal structure. Its lower symmetry originates from a Peierls distortion of the Mn chains. This distortion nearly opens the gap at the Fermi level, but despite the strong dimerization and the proximity of MnB4 to the insulating state, we find indications for a sizable paramagnetic effective moment of about 1.7 μB/f.u., ferromagnetic spin correlations, and, even more surprisingly, a prominent electronic contribution to the specific heat. However, no magnetic order has been observed in standard thermodynamic measurements down to 2 K. Altogether, this renders MnB4 a structurally simple but microscopically enigmatic material; we argue that its properties may be influenced by electronic correlations. [ABSTRACT FROM AUTHOR]

The solid solution YbxCa1-xC2 (0 ≤ x ≤ l) was synthesized by reaction of the elements at 1323 K. The crystal structures within this solid solution, as elucidated from synchrotron powder diffraction data, depend on x and exhibit some interesting features that point to a structure dependent valence state of Yb. Compounds with x ≥ 0.75 crystallize in the tetragonal CaC2 type structure (I4/mntm, Z = 2) and obey Vegard's law; for x ≥ 0.75 the monoclinic ThC2 type structure (C2/c, Z = 4) is found, which coexists with the monoclinic CaC2-III type structure (C2/m, Z = 4) for x ≤ 0.25. The monoclinic modifications show a strong deviation from Vegard's law. Their unit cell volumes are remarkably larger than expected for a typical Vegard system. HERFD-XANES spectroscopic investigations reveal that different Yb valence states are responsible for the observed volume anomalies. While all tetragonal compounds contain mixed-valent Yb with ~75% Yb3+ (similar to pure YbC2), all monoclinic modifications contain exclusively Yb2+. Therefore, YbxCa1-xC2 is a very rare example of a Yb containing compound showing a strong structure dependence of the Yb valence state. Moreover, temperature dependent synchrotron powder diffraction, neutron TOF powder diffraction, and HERFD-XANES spectroscopy experiments reveal significant Yb valence changes in some compounds of the YbxCa1-xC2, series that are induced by temperature dependent phase transitions. Transitions from the tetragonal CaC2 type structure to the monoclinic ThC2 or the cubic CaC2-IV type structure (Fm3m, Z = 4) are accompanied by drastic changes of the mean Yb valence from ~2.70 to 2.0 in compounds with x = 0.75 and x = 0.91. Finally, the determination of lattice strain arising inside the modifications with ordered dumbbells (ThC2 and CaC2 type structures) by DSC measurements corroborated our results concerning the close relationship between crystal structure and Yb valence in the solid solution YbxCa1-xC2. [ABSTRACT FROM AUTHOR]

Abstract: Thermal stability, oxygen non-stoichiometry and electrical conductivity of LaNi0.6Fe0.4O3 −δ were investigated in the temperature region of 20–1000°C in Ar/O2 gas flows at oxygen partial pressures between 0.5 and 21,000Pa. Diffusion mobility was measured in Ar/O2 gas flow at pO2 =18Pa. Crystal structure of this compound was found to be stable at the mentioned experimental conditions. LaNi0.6Fe0.4O3 −δ is a p-type semiconductor with metallic type conductivity above 150°C at the investigated pO2 range. Two different (fast and slow) oxygen exchange areas on the temperature-pO2 diagram were established, which are due to two different oxygen anion positions in the double B-site mixed perovskite structure. Oxygen non-stoichiometry in the fast oxygen exchange region reaches about 0.005 of oxygen atomic index. Chemical diffusion and oxygen surface exchange coefficients do not vary at 600–800°C, but show visible increase above 800–850°C. [Copyright &y& Elsevier]

The phase stability, crystal structure, and magnetic properties of perovskite-like nonstoichiometric Sr2ColrO6-δ were studied. Oxygen deficiency can be well controlled and reversibly varied up to δ = 0.33. A single phase exists at least for partial oxygen pressures between 10-5 and 1 bar at 1273 K, followed by phase decomposition at higher temperature with the elimination of metallic Ir and the formation of a new phase with approximately Sr3ColrO6 composition crystallizing in K4CdCl6 structure type. The structural features of Sr5ColrO6-δ are dependent on both temperature and oxygen contest and were determined by synchrotron and neutron powder diffraction. Both the increasing amount of oxygen vacancies at constant temperature and increasing temperature at constant oxygen content result in the same higher crystal symmetry of Sr2ColrO6-δ: (1) The oxygen-stoichiometric phase Sr2CotrO6.00 is monoclinic (12lm or P21/n) at room temperature but cubic (Fm-3m) for Sr2CslrO5.67. (2) A sequence of phase transitions 12/m + P21/n ["Multiple line equation(s) cannot be represented in ASCII text"] 12/m ["Multiple line equation(s) cannot be represented in ASCII text"] 14/m ["Multiple line equation(s) cannot be represented in ASCII text"] Fm - 3m was observed for Sr2ColrO6.00 in air. All Sr2CotrO6-δ compositions show weak ferromagnetism at low temperature with a canted but predominantly antiferromagnetic ground state. The magnetic ordering temperature decreases monotonously with increasing oxygen deficiency, while pronounced extrema are observed for the paramagnetic moment and the Curie-Weiss temperature at an oxygen deficiency δ ≈ which corresponds to the P21/n ↔ 12/m phase transformation. [ABSTRACT FROM AUTHOR]

Abstract: Silver diiron tris(oxomolybdate), α-AgFe2(MoO4)3, was synthesized in sealed silica tubes at 1050K and is isostructural to α-NaFe2(MoO4)3, determined by single-crystal X-ray diffraction (space group P−1, a =6.9320(7)Å, b =6.9266(6)Å, c =10.9732(13)Å, α =81.197(8)°, β =83.456(9)°, γ =81.352(8)° at 300K, Z =2). The crystal structure is built up from both monomers and edge-sharing dimers of [FeO6]-octahedra, which are linked with each other by isolated [MoO4]-tetrahedra to a three-dimensional network. Ag ions are situated on a site with four near oxygen neighbours. Thermal expansion is most pronounced along the c-axis, while the angle α decreases with increasing temperature. Antiferromagnetic ordering is indicated by a sharp maximum in the temperature dependence of magnetization at 21.5(5)K, and a magnetic moment of 5.36(1)μB per Fe-ion was derived from the Curie constant in the paramagnetic region. The collinear antiferromagnetic structure with propagation vector k =(0,½,½) and an ordered magnetic moment of 4.62(9)μB per Fe-ion were deduced from neutron powder diffraction data and give evidence for an underlying magnetic interaction mechanism, resulting in rather strong and long-ranged couplings. Mössbauer spectroscopy shows a change in the electronic configuration on the two distinct Fe sites between room temperature and 150K, accompanied by an increase of the average Fe–O distance for one site and a shrinking one for the other as expected for charge ordering in a mixed valence compound with Fe(II) and Fe(III). [Copyright &y& Elsevier]

Abstract: Different polymorphs of MRe2O6 (M i) with rutile-like structures were prepared using high-pressure high-temperature synthesis. For syntheses temperatures higher than ∼1573K, tetragonal rutile-type structures (P42/mnm) with a statistical distribution of M- and Re-atoms on the metal position in the structure were observed for all three compounds, whereas rutile-like structures with orthorhombic or monoclinic symmetry, partially ordered M- and Re-ions on different sites and metallic Re–Re-bonds within Re2O10-pairs were found for CoRe2O6 and NiRe2O6 at a synthesis temperature of 1473K. According to the XPS measurements, a mixture of Re+4/Re+6 and M 2+/M 3+ is present in both structural modifications of CoRe2O6 and NiRe2O6. The low-temperature forms contain more Re+4 and M3+ than the high-temperature forms. Tetragonal and monoclinic modifications of NiRe2O6 order with a ferromagnetic component at ∼24K, whereas tetragonal and orthorhombic CoRe2O6 show two magnetic transitions: below ∼17.5 and 27K for the tetragonal and below 18 and 67K for the orthorhombic phase. Tetragonal FeRe2O6 is antiferromagnetic below 123K. [Copyright &y& Elsevier]

The title solid solution (0 ≤ x ≤ 1) is prepared from the elements (Ta bomb, 1323 K, 24 h) and characterized by XANES, and synchrotron and neutron powder diffraction. [ABSTRACT FROM AUTHOR]

Abstract: High-resolution in situ X-ray powder diffraction applying synchrotron radiation has been used to examine the occurring crystal structures and the thermal behaviour of the solid solution Pr1− x La x AlO3 in a wide temperature range 12–1173K. At room temperature all studied samples in the whole composition range of the pseudo-binary system PrAlO3–LaAlO3 adopt a rhombohedral perovskite structure. The phases Pr1− x La x AlO3 with x=0.56 and 0.66 undergo a sequence of three phase transitions I2/m↔Imma↔R3¯c↔Pm3¯m. For the sample with x=0.24 a series of four (I4/mcm↔I2/m↔Imma↔R3¯c↔Pm3¯m) phase transitions has been observed and for x=0.86 two transformations were apparent (I2/m↔R3¯c↔Pm3¯m). Crystal structure parameters for all studied compositions Pr1− x La x AlO3 have been determined. Based on in situ powder diffraction and DTA/DSC data, the phase diagram of the pseudo-binary system PrAlO3–LaAlO3 has been constructed. [Copyright &y& Elsevier]