Temperature Dependence of the Transmission Spectra of Silicate Glasses Containing CdS<Subscript>1−<Emphasis Type=Italic>x</Emphasis></Subscript>Se<Subscript><Emphasis Type=Italic>x</Emphasis></Subscript> Semiconducting Nanocrystals

The transmission spectra of silicate glasses containing CdS_{1 − x} Se _x semiconducting nanocrystals of various sizes are investigated in the temperature range 20–300°C. It is shown that for explaining optical properties of these materials, not only the nanocrystal sizes, but also the structural changes occurring in nanocrystals during their formation must be taken into account.     

Modifying the properties of lead titanate in PbTi<Subscript>1 − <Emphasis Type=Italic>x</Emphasis></Subscript>Mn<Subscript><Emphasis Type=Italic>x</Emphasis></Subscript>O<Subscript>3</Subscript> solid solutions

Spontaneous deformation in the PbTi_{1 − x} Mn _x O₃ system at room temperature is found to decrease as x increases, indicating a drop in the temperature of the ferroelectric phase transition.     

Cascade of phase transitions in the Fe<Subscript>1 − <Emphasis Type=Italic>x</Emphasis></Subscript>Co<Subscript><Emphasis Type=Italic>x</Emphasis></Subscript> monolayer

The reorientation phase transitions occurring in FeCo alloy monolayers have been investigated as a function of the cobalt concentration with inclusion of the magnetodipole and magnetoelastic interactions. The kinetic values of the cobalt concentration corresponding to the phase transition points have been determined and the phase diagram of the system under investigation has been constructed.     

Phase composition and the structure of (1–<Emphasis Type="Italic">x</Emphasis>)KNO<Subscript>3</Subscript> + <Emphasis Type="Italic">x</Emphasis>Al<Subscript>2</Subscript>O<Subscript>3</Subscript> nanocomposites by X-ray diffraction

The phase composition and the structural properties of potassium nitrate KNO₃ and its heterogeneous composites with nanometer-sized powder of aluminum oxide Al₂O₃ have been studied by X-ray diffraction at various concentrations of an Al₂O₃ nanopowder. It is found that, in the (1–x)KNO₃ + xAl₂O₃ nanocomposites, additional high-temperature rhombohedral phase of potassium nitrate (phase III) with lattice parameters a = 5.4644 Å and c = 9.0842 Å. With increasing concentration of Al₂O₃ nanopowder, the content of the main potassium nitrate phase (phase II) is found to significantly decrease, and the relative fraction of the phase III in the total content of the nitrate in the composite composition increases. This phase is assumed to be “frozen” in the nanocomposite at the KNO₃–Al₂O₃ interface. The estimated size of KNO₃ crystallites in the phase III is more than 20 nm.     

Absorption spectra of thin layers of solid solutions Cs<Subscript>2</Subscript>(Cd<Subscript>1 − <Emphasis Type=Italic>x</Emphasis></Subscript>Zn<Subscript><Emphasis Type=Italic>x</Emphasis></Subscript>)I<Subscript>4</Subscript>

The excitonic absorption spectra of thin films of ferroelectric Cs₂CdI₄ and Cs₂ZnI₄ solid solutions are studied for the first time. It is found that, within the whole range of molar concentrations x, the spectra of Cs₂(Cd_{1 − x} Zn _x )I₄ comprise two bands that originate from the bands of the two compounds. It is shown that the exciton transfer occurs most efficiently between the tetrahedrons CdI₄ and ZnI₄ along the b axis of the crystal. Unusual behavior of the concentration with regards to the maxima of long-wavelength excitonic bands E _m (x) agrees well with the developed theory that takes into account dependence on x of the matrix element of the intertetrahedron exciton transfer and that is similar to the theory of Davydov’s splitting in molecular crystals.     

Magnetic properties of multiferroics Bi<Subscript>1 – <Emphasis Type=Italic>x</Emphasis></Subscript>Sm<Subscript><Emphasis Type=Italic>x</Emphasis></Subscript>FeO<Subscript>3</Subscript> synthesized under high pressure

The magnetic properties of the multiferroics obtained upon isovalent substitution of samarium cations for bismuth cations in BiFeO₃. The samples have been synthesized by solid-phase reactions under conditions of a cold pressing at high (4 GPa) pressure. The correlation between the structure and the magnetic properties of the multiferroics has been found based on analyzing the experimental data.     

Laser assisted electrochemical preparation of micro and nanopores in Ga<Subscript><Emphasis Type=Italic>x</Emphasis></Subscript>In<Subscript>1−<Emphasis Type=Italic>x</Emphasis></Subscript>P

We report on the preparation of Ga(x)In(1−x)P/GaAs lattice matched heterostructures by liquid phase epitaxy and their electrochemical etching to prepare porous networks. We show that the process of formation of pores strongly depends on the electrolyte, on the applied current/voltage anodization regime, and that illumination is a crucial factor in obtaining fine porous structures with a high degree of self-organization.     

The Synthesis of Ce<Subscript>1 – <Emphasis Type=Italic>x</Emphasis></Subscript>Zr<Subscript><Emphasis Type=Italic>x</Emphasis></Subscript>O<Subscript>2</Subscript> Oxides in Supercritical Alcohols and Catalysts for Carbon Dioxide Reforming of Methane on Their Basis

The effect of the features of starting zirconium compounds on the solvothermal synthesis of mixed Ce–Zr oxides in a flow reactor using ethanol and isopropanol as a supercritical medium was studied. The phase composition and structural properties of the synthesized samples were investigated using X-ray diffraction analysis (XRD) and Raman spectroscopy. The morphology and textural properties were studied by transmission electron microscopy (TEM) and thermal desorption of nitrogen. It was found that the use of zirconium oxychloride or acetate as the starting substances results in the formation of a mixture of phases enriched with cerium or zirconium, whereas the use of zirconium butoxide with acetylacetone as a complexing agent allows obtaining a homogeneous solid solution. The catalytic properties of the synthesized oxides with supported Ni were tested in methane dry reforming (MDR). The catalyst containing a single-phase oxide synthesized in the presence of acetylacetone exhibited much higher activity, selectivity and coking stability.     

Calorimetry of (1 − <Emphasis Type="Italic">x</Emphasis>)BaTiO<Subscript>3</Subscript>-<Emphasis Type="Italic">x</Emphasis>Ba(Mg<Subscript>1/3</Subscript>Nb<Subscript>2/3</Subscript>)O<Subscript>3</Subscript> solid solutions

Phase transitions in ceramic samples of (1 ? x)BaTiO₃-xBa(Mg_1/3Nb_2/3)O₃ solid solutions were studied by differential scanning calorimetry for x = 0, 0.01, 0.02, and 0.03 in the temperature ranges 255–290 K and 310–410 K. The experimental data obtained were used to derive the thermodynamic parameters of the phase transitions occurring at T _c ≈ 400?300 K and T ₁ ≈ 290?300 K and construct the concentration phase diagram.     

Metallization and spin crossover in Magnesiowüstite (Mg<Subscript>1 − <Emphasis Type=Italic>x</Emphasis></Subscript>Fe<Subscript><Emphasis Type=Italic>x</Emphasis></Subscript>O) at high pressures

The pressure-temperature phase diagram of magnesiowüstite has been constructed using the many-electron LDA+GTB approach. The phase diagram includes a quantum critical point at P _c = 55 GPa and has a symmetrical distribution of high-spin and low-spin states. The existence of a metallic state in a narrow temperature range above the critical point is predicted.     

Morphology and composition tailoring of Co<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>Fe<Subscript>3 − <Emphasis Type="Italic">x</Emphasis></Subscript>O<Subscript>4</Subscript> nanoparticles

Nano-octahedra of cobalt ferrite Co _x Fe_3???xO₄ (1?≤?x?<?2), with a broad size distribution around 15–20 nm, were synthesized by a hydrothermal method using nitrates as precursors. For the first time, single-phased nano-octahedra of cobalt-rich ferrite Co _x Fe_3???xO₄ (x?=?1.5) were synthesized. The nano-octahedra are crystallized in a normal spinel structure, with tetrahedral sites occupied by Co²⁺. This specific octahedral shape was obtained with anionic, cationic, and nonionic surfactants. The nature of the surfactant influenced the chemical composition of the powder and the size of the nano-octahedra. The {100} truncation of the octahedra is more pronounced for the small particles. For the first time, single-phased nanoparticles with as much as x?=?1.8 cobalt were synthesized with ethylene glycol as solvent. These nanoparticles, around 8 nm in size, have no specific shape and possess a lacunar spinel structure similar to maghemite. The samples were characterized by X-ray diffraction, transmission electron microscopy, and energy-dispersive spectroscopy.

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