Importance of the many-body effects on the structural properties of the novel iron oxide FeO.

The importance of many-body effects on the electronic and magnetic properties and stability of different structural phases was studied in novel iron oxide FeO. It was found that while Hubbard repulsion hardly affects the electronic spectrum of this material (*/ ≈ 1.2), it strongly changes its phase diagram, shifting critical pressures of structural transitions to much lower values.

Mapping the Energetics of Defect States in CuZnSnS films and the Impact of Sb Doping.

The sub-bandgap levels associated with defect states in CuZnSnS (CZTS) thin films are investigated by correlating the temperature dependence of the absorber photoluminescence (PL) with the device admittance spectroscopy. CZTS thin films are prepared by thermolysis of molecular precursors incorporating chloride salts of the cations and thiourea. Na and Sb are introduced as dopants in the precursor layers to assess their impact on Cu/Zn and Sn site disorder, respectively.

New Metastable Baro- and Deformation-Induced Phases in Ferromagnetic Shape Memory NiMnGa-Based Alloys.

Structural and phase transformations in the microstructure and new metastable baro- and deformation-induced phases of the NiMnGa alloy, typical of the unique class of ferromagnetic shape memory Heusler alloys, have been systematically studied for the first time. Phase X-ray diffraction analysis, transmission and scanning electron microscopy, and temperature measurements of electrical resistivity and magnetic characteristics in strong magnetic fields were used. It was found that in the course of increasing the pressure from 3 to 12 GPa, the metastable long-period structure of martensite modulated according to the 10-type experienced transformation into a final non-modulated 2 structure.

Giant Room-Temperature Power Factor in p-Type Thermoelectric SnSe under High Pressure.

Materials that can efficiently convert heat into electricity are widely utilized in energy conversion technologies. The existing thermoelectrics demonstrate rather limited performance characteristics at room temperature, and hence, alternative materials and approaches are very much in demand. Here, it is experimentally shown that manipulating an applied stress can greatly improve a thermoelectric power factor of layered p-type SnSe single crystals up to ≈180 µW K cm at room temperature.

Effect of Doping on the Electronic Structure of the Earth's Lower Mantle Compounds: FeXO with X = C, Al, Si.

The effect of the mutual doping of C, Si, and Al atoms on the electronic structure and magnetic properties of FeXO (X = C, Al, Si) compounds, which are constituent compounds of the Earth's lower mantle, was studied. In our first principles calculations, it was found that doping with carbon for both FeSiO and FeAlO leads to the transition of the compound from a half-metallic state to a metallic one. The values of the magnetic moments of Fe were obtained for pure and doped compounds.

Manifestation of the Jahn-Teller effect subject to quadraticT⊗e+t2problem in ultrasonic attenuation. Case study of CaF:Cr crystal with isovalent and aliovalent substitution.

A new approach is introduced to obtain information about the adiabatic potential energy surface of the Jahn-Teller (JT) complexes subject to theT⊗e+t2problem in doped crystals. It employs simulation of the contribution of the JT sub-system to ultrasonic attenuation with account of three mechanisms of relaxation and subsequent comparison with the experimental data on temperature dependence of the attenuation obtained with the use of doped crystal and nominally pure one. The approach has been applied to the CaFcrystal doped with chromium.

Models of Ni- and Co-ion occupation in LiNiCoPOorthophosphate and its magnetic structure.

The neutron diffraction, magnetic and heat capacity measurements have been carried out to study the polycrystalline sample LiNiCoPOprepared by the glycerol-nitrate synthesis method. Models of Ni- and Co-ion occupation the 4octahedral position in a crystal structure LiNiCoPOare calculated for a paramagnetic state. The best model is the Ni- and Co-ions occupy the 4site inpatent space-group in sequence Ni-Co-Ni-Co or Co-Ni-Co-Ni.

Tensile Deformation and Fracture Behavior of API-5L X70 Line Pipe Steel.

Thermo-mechanical controlled processing (TMCP) is employed to obtain the required level of mechanical properties of contemporary HSLA steel plates utilized for gas and oil pipeline production. The strength and crack resistance of pipeline steels are mainly determined by its microstructure and crystallographic texture. In this study, the influence of the structural and textural states of industrially produced API-5L X70-X80 pipeline steels on tensile mechanical properties was analyzed.

Cavitation Resistance of WC-10Co4Cr and WC-20CrC-7Ni HVAF Coatings.

Machines operating in aqueous environments may be subjected to cavitation damage during operation. This study aims to evaluate the cavitation resistance of WC-10Co4Cr and WC-20CrC-7Ni coatings under cavitation erosion conditions with additional electrochemical effects. The coatings were deposited on AISI 1040 steel substrates using a high velocity air fuel thermal spray process.

Silver Flowerlike Structures for Surface-Enhanced Raman Spectroscopy.

Micro- and nanoflowers are a class of materials composed of particles with high surface-to-volume ratio. They have been extensively studied in the last decade due to simple preparation protocols and promising applications in biosensing, as drug delivery agents, for water purification, and so on. Flowerlike objects, due to their highly irregular surface, may act also as plasmonic materials, providing resonant coupling between optical waves and surface plasmon excitations.

Microstructural Features in Multicore Cu-Nb Composites.

The study is devoted to heavily drawn multicore Cu-18Nb composites of cylindrical and rectangular shapes. The composites were fabricated by the melt-and-deform method, namely, 600 in situ rods of Cu-18%Nb alloy were assembled in a copper shell and cold-drawn to a diameter of 15.4 mm (e = 10.

Dimerization in α-TiCland α-TiBr: the DFT study.

A series of DFT calculations for two layered compounds with honeycomb lattice-α-TiCland α-TiBrhas been performed. It was shown that the symmetric SU(4) spin-orbital model recently proposed forsystems with honeycomb lattice cannot be realized in these titanates because they dimerize in the low temperature phase. This explains experimentally observed drop in magnetic susceptibility of α-TiBr.

Structural Stability and Properties of Marokite-Type γ-MnO.

We synthesized single crystals of marokite (CaMnO)-type orthorhombic manganese (II,III) oxide, γ-MnO, in a multianvil apparatus at pressures of 10-24 GPa. The magnetic, electronic, and optical properties of the crystals were investigated at ambient pressure. It was found that γ-MnO is a semiconductor with an indirect band gap of 0.

Texturing and Phase Evolution in Ti-6Al-4V: Effect of Electron Beam Melting Process, Powder Re-Using, and HIP Treatment.

The research demonstrates microstructural changes and development of specific texture in Ti-6Al-4V specimens produced by electron beam melting (EBM) under different conditions. The effect of two factors, namely, raw material (powder) recycling and hot isostatic pressing (HIP), on the EBM produced samples structure and properties, has been explored. The as-printed and treated samples were investigated using electron backscattered diffraction (EBSD) analysis.

Synthesis of Ilmenite-type ε-MnO and Its Properties.

In contrast to the corundum-type AX structure, which has only one crystallographic site available for trivalent cations (e.g., in hematite), the closely related ABX ilmenite-type structure comprises two different octahedrally coordinated positions that are usually filled with differently charged ions (e.

Ferromagnetic Resonance and Antiresonance in Composite Medium with Flakes of Finemet-Like Alloy.

Propagation of microwaves is studied in a composite material containing flakes of Fe-Si-Nb-Cu-B alloy placed into an epoxyamine matrix. The theory is worked out, which permits to calculate the coefficients of the dynamic magnetic permeability tensor and the effective magnetic permeability of the transversely magnetized composite. The measurements of magnetic field dependences of the transmission and reflection coefficients were carried out at frequencies from 12 to 38 GHz.

Transmission, Reflection and Dissipation of Microwaves in Magnetic Composites with Nanocrystalline Finemet-Type Flakes.

The microwave properties of a composite material containing flakes of finemet-type nanocrystalline alloy placed in the epoxy matrix have been investigated. Two compositions have been studied: with 15% and 30% flakes. Frequency dependences of transmission and reflection coefficients are measured in the frequency range from 12 to 38 GHz.

Itinerant magnetism of chromium under pressure: a DFT+DMFT study.

We consider electronic and magnetic properties of chromium, a well-known itinerant antiferromagnet, by a combination of density functional theory (DFT) and dynamical mean-field theory (DMFT). We find that electronic correlation effects in chromium, in contrast to its neighbors in the periodic table, are weak, leading to the quasiparticle mass enhancement factor*/≈ 1.2.

Magnetic and magneto-thermal properties of ferrimagnetic alloys (ErY)(CoFe)and their dependence on the orientations of resultant and sublattice magnetizations.

In this paper structure, magnetic and magneto-thermal properties: magnetic entropy change (Δ) and refrigeration capacity () of ErY(CoFe)alloys (= 0, 0.2, 0.4, 0.

A nonlinear evolution of the structure, morphology, and optical properties of PbS-CdS films with cadmium nitrate in the reaction mixture.

Herein, we describe the nonlinear processes for the formation of thin films of the PbS-CdS system using chemical bath deposition with a gradual change in the cadmium nitrate content in the reaction mixture. The morphology of films was studied via scanning electron microscopy and atomic force microscopy. The mechanism for the formation of thin-film compounds can be considered as cluster-particle aggregation (diffusion-limited aggregation).

Non-collinear antiferromagnetism to compensated ferrimagnetism in Ti(FeCo) ( = 0, 0.5 and 1) alloys: experiment and theory.

The manifestation of the structural and magnetic properties of Co substituted TiFe2 is investigated using powder X-ray diffraction, magnetization and density functional theory calculations. The alloys TiFe2 and TiFeCo crystallize in the hexagonal structure (P63/mmc) with a reduction in the lattice parameters of TiFeCo (by about 0.51% in a and 0.

Effect of the Titanium Self-Intercalation on the Electronic Structure of TiSe.

The effect of the superstoichiometric Ti intercalation on the electronic structure of TiSe was studied by using X-ray photoelectron spectroscopy in nonresonant and resonant modes along with the DOS (density of states) calculations. It was shown that the presence of the Ti atoms in the interlayer space leads to the formation of the Ti 3d/Ti 3d hybridized band between the Ti atoms in the regular lattice positions and Ti atoms in the interlayer space. The charge transfer to the conduction band was not observed in this case.

Magnetism, Conductivity and Spin-Spin Interactions in Layered Hybrid Structure of Anionic Radicals [Ni(dmit)] Alternated by Iron(III) Spin-Crossover Complex [Fe(III)(3-OMe-Saltrien)] and Ferric Moiety Precursors.

In this study, crystals of the hybrid layered structure, combined with Fe(III) Spin-Crossover (SCO) complexes with metal-dithiolate anionic radicals, and the precursors with nitrate and iodine counterions, are obtained and characterized. [Fe(III)(3-OMe-Saltrien)][Ni(dmit)] (), [Fe(III)(3-OMe-Saltrien)]NO·HO (), [Fe(III)(3-OMe-Saltrien)]I () (3-OMe-Saltrien = hexadentate NO Schiff base is the product of the condensation of triethylenetetramine with 3-methoxysalicylaldehyde; Hdmit = 2-thioxo-1,3-dithiole-4,5-dithiol). Bulk SCO transition was not achieved in the range 2.

Structural stability of CuAlOunder pressure.

Structural properties of CuAlO, which was recently argued to show unusual suppression of the Jahn-Teller distortions by the spin-orbit coupling, are investigated under pressures up to 6 GPa. Analysis of x-ray powder diffraction experiments shows that CuAlOgets unstable and decomposes onto CuO and AlOat pressures ∼6 GPa and temperature ∼1000 K. This finding is complemented by the density-functional theory ++ spin-orbit coupling calculations, which demonstrate that this instability is partially driven by a (relatively) large compressibility of strongly Jahn-Teller distorted CuO.

Correlation of elastic and optoelectronic properties near structural phase transition in organic-inorganic lead iodide perovskite single crystals.

The experimental evidence of the influence of the structural phase transition on the elastic and optoelectronic properties of CHNHPbIsingle crystals has been reported. A peak in the attenuation for longitudinal and shear ultrasonic waves and a step-like anomaly in their velocity have been found near the structural the orthorhombic-to-tetragonal phase transition (160 K). The narrow hysteresis observed in the temperature dependences of the elastic properties confirms that this is the first-order phase transition.