[en] Langatate crystals with the nominal composition La₃(Ga_0.5Ta_0.5)Ga₅O₁₄ grown by Czochralski pulling along <0001> have been studied by X-ray and neutron diffraction before and after post growth annealing in air and vacuum. Their compositions are determined, the relationship between the Ga/Ta ratio and unit-cell parameters is established, and their color (colorless, yellow, and orange crystals) is shown to depend on their oxygen content and the growth and annealing conditions. Vacuum annealing at sufficiently high temperatures leads to precipitation of a green phase, La(Ta,Ga)³⁺O₃. (authors)

[en] In studies of phase equilibria in the U-Co-Ga system at 600 degrees C, the authors found a ternary compound close in composition to U₂Co₂Ga. A sample of composition U₄₂Co₄₀Ga₁₈ was prepared by arc-melting a mixture of high-purity U (99.4%), Co (99.99%), and Ga (99.99%) in a purified argon atmosphere. The sample was homogenized at 600 degrees C for 720 h in an evacuated quartz tube and then quenched in cold water. In structure determination, the authors used a DRON-4-07 powder X-ray diffractometer (CuK_α radiation, 0.02 degrees 2θ scan step) and the CSD software package. The X-ray diffraction pattern showed tetragonal symmetry, with lattice parameters obtained from least-squares refinements a = 0.707729(5) and c = 0.34707(4) nm

[en] An analysis of data collected over five years on the thermal conductivity, thermal EMF and Hall coefficient, magnetic susceptibility at 30-300 K, specific heat, and theoretical work devoted to high temperature superconductivity in oxide superconductors belonging to the systems Y-Ba-Cu-O, Bi(Pb)-Sr-Ca-Cu-O, Tl-Ba-Ca-Cu-O has led to an unexpected conclusion. From the optical properties of single crystal superconductors belonging to the systems indicated, the authors conclude that the Bardeen-Cooper-Schrieffer theory is probably not applicable. Apparently Cooper pairs do not exist in high temperature superconductors, but are assumed as an expedient approximation for a description in terms of traditional superconductivity theory. The authors realize that this proposal is controversial and are prepared to present a large amount of data to support it

[en] This paper studies the phase transitions in Ta₂0₅ and the influence of hot pressing on these transitions in the interval 1100-1600 degrees C. The specimens were investigated by x-ray and metallographic methods. It is found that under hot pressing of the specimens the temperature of the beta to alpha phase transition is reduced to 1200 degrees C; the unit-cell volume and density change by 4.2%. An increase in the pressing temperature to 1600 degrees C leads to a decrease in the unit-cell volume of the alpha phase and a rise in density by 1.5%

[en] This paper reports x-ray, Auger, and photoelectric studies on surface layers in PLTZ electrooptic ceramic (lanthanum-modified lead titanate-zirconate), as the composition and structure of the surface largely determine the properties of the ceramic. The studies show that the polished surface of transparent TsTSL-10 ferroelectric ceramic has a complicated structure. An upper layer of thickness of about 0.1 microm is amorphous or highly disordered. The outer part of this layer is depleted in Ti and Zr. That layer is removed only after chemical etching. According to the photoelectric measurements, the internal (defective) layer shows an elevated photocarrier recombination rate

[en] The yttrium ions in the Y₅S₇ lattice are found in the di- and trivalent states. The authors replaced a portion of the divalent yttrium ions by divalent Cd, Cr, Eu, Yb, Fe, Co and Ni ions and the trivalent yttrium ions were replaced by other trivalent rare earth ions. Alloys were synthesized for M - Cd, Zn, Eu, Yb, Cr, and Ni. A detailed x-ray diffraction study shows that two structural types are characteristic for MLn₄S₇ and MLn₄Se₇. All of these compounds have p-type conductivity. The specific electrical conductance and thermoelectromatic force are 0.70 S/cm and 25 microv for CrLa₄S₇ at 300 K, while the analogous values for CrCe₄S₇ are 0.47 S/cm and 13 microV

[en] In order to study the PbTe-Gd₂Te₃ system, the authors synthesized alloys starting from the PbTe side at 1300-1500 K. To establish the equilibrium conditions, alloys were heated in evacuated quartz ampuls at 770 K for 600 h and then quenched in ice water. Investigation of the mmcrostructure indicated that alloys of up to 4 mole % Gd₂Te₃ are single-phase. With increase of Gd₂Te₃ content, two-phase alloys form

[en] The authors determined the melting point of dueterated cesium hydrogen arsenate of composition CsH /SUB 0.1/ D /SUB 1.9/ AsO₄ melts. Specimens for investigation of the system were prepared by fusion of appropriate amounts of CsH₂AsO₄ and CsH /SUB 0.1/ D /SUB 1.9/ AsO₄ in sealed quartz ampuls. In addition, the unit-cell parameters of the phases of the specimens practically did not differ from the corresponding parameters of the starting products over the entire range of concentrations

[en] The compound HoUTe_2.9 was obtained from the elements by the thermal evacuation method in a graphitized ampule at ∼1330 K for 2 h. Then it was homogenized and melted at ∼1900 K in a hermetically sealed molybdenum crucible in a DTA instrument. After synthesis, X-ray phase and microstructural analysis were carried out. The compound HoUTe_2.9 crystallizes in a rhombic structure of the type Sb₂S₃, space group Pbnm. The unit cell parameters are: a = 1.202; b = 1.157; c = 0.429 nm. The compound YbUTe_5.8 was obtained from the element by the thermal evacuation method in a graphitized quartz ampule at ∼1400 K with subsequent annealing at ∼800 K for 25 h. After synthesis, the authors carried out X-ray phase and microstructural analysis. The compound YbUTe_5.9 crystallizes in a rhombic structure of the type NdTe₃. The unit cell parameters are: a = b = 0.432; c = 2.495 nm. The authors studied the magnetic properties of the compounds on a magnetic balance in the interval 80-300 K for a magnetic field strength of 38·10⁴ A/m. 2 refs., 2 figs

[en] The incorporation of IV-Group elements into silicon single crystals slightly increases the stability of their electric resistance to the effect of radioactive radiation. In this work, the authors studied the effect of irradiation by fast electrons of 8-MeV energy on the resistivity and lifetime of minority charge carriers in titanium-, zirconium-, and hafnium-doped silicon single crystals