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The connection between the peak of density of electronic states at ~ 0.4 eV below the Fermi level and the localization of charge carriers at compression of the height of CuO5 pyramids has been found by a comparison of experimental angle-resolved photoemission spectra data for Y0.9Ca0.1Ba2Cu3O6.8 single crystal and calculations of the electronic structure in a framework of the density functional theory. Both experiment and calculation are performed using 34.6 and 90.2 eV photon energy. The excitation energy does not have any noticeable influence on the peak of density of electronic states. Crystal structure distortions on the crystal surface result in observation of localized electronic states below the temperature of superconducting transition. [ABSTRACT FROM AUTHOR]

High-entropy single-phase superconducting oxide Y0.2Nd0.2Eu0.2Sm0.2Ho0.2Ba2Cu3Oy was synthesized. For samples with different values of oxygen content thermogravimetry, x-ray diffraction and magnetic properties were measured. Orthorombitity, critical temperature, and critical current grow with oxygen nonstoichiometry value y and corresponds to those for "low-entropy" YBa2Cu3Oy-type superconductors. The increase of the oxygen content leads to a decrease of "buckling" CuO2 layers and does not lead to a decrease in the Ba–O distance. [ABSTRACT FROM AUTHOR]

Transition metal trialuminides of the Al3X type of groups 4 and 5 of the periodic system have reduced density, high melting points, and corrosion resistance. Aluminides with a cubic lattice of the Al3Sc type can be used as a nucleating phase for aluminum alloys. However, low plasticity and a tetragonal lattice limit their application. In this work, we stabilized the metastable cubic lattice of Al3X-type aluminides by replacing aluminum with copper. The conditions for the formation of L12 metastable aluminides in the Al–Cu–TM (TM: Ti, Zr, Hf) alloys were studied using a wide range of copper concentrations. A high concentration of copper (hypereutectic alloys) is the one of the necessary conditions for the formation of (Al1−xCux)3Ti, (Al1−xCux)3Zr, (Al1−xCux)3Hf aluminides. With an increase in the copper concentration, the number of metastable aluminides sharply increased. The process of their formation strongly depended on the sequence of dissolution of the corresponding components in the melts. The low volume fraction of precipitated titanium aluminides was the result of insufficient supersaturation of α-Al with titanium (at the peritectic temperature) compared to that for alloys with zirconium and hafnium. Under identical synthesis conditions in the crystal lattice of metastable aluminides formed in experimental Al–Cu–Ti, Al–Cu–Zr, Al–Cu–Hf alloys, copper was found to substitute up to 8, 10, and 13 at.% of aluminum, respectively. The crystallographic and dimensional similarities of the lattices in metastable transition metal aluminides and in α-Al suggest their usefulness as modifying additions in aluminum-based alloys. [ABSTRACT FROM AUTHOR]

New intercalation compounds Cr x ZrSe 2 were synthesized and thoroughly studied. Cr atoms were found to occupy the positions both tetrahedrally and octahedrally coordinated by the Se atoms in the interlayer gap. The magnetic properties and electrical resistivity were studied in the temperature ranges of 2.4-300 K and 80-340 K, respectively. The compounds change their behavior from semiconducting ( x = 0.1) to metallic ( x > 0.1). The magnetic interaction strongly depends on the Cr content and temperature. The spin-glass state with antiferromagnetic interaction exists at T < T crit for Cr x ZrSe 2 with x ≤ 0.2, while at x ≥ 0.3 ferromagnetic contribution arises as well. The single crystals of Cr x ZrSe 2 were grown to study the electronic structure of the materials. A combination of the X-ray photoelectron spectroscopy (including that across Cr 2p-3d and Zr 3p-4d resonance) and X-ray absorption spectroscopy methods allowed to propose the location of the Cr 3d-states in the Se 3p-Zr 4d energy gap.