Analysis of the transition zone in combined metal/reinforced-plastic shells

The bending stresses in the conical joint zone of cylindrical shells composed of two different materials are determined for the case of internal pressure. The effect of the length of the joint on these stresses is investigated using parameters typical of steel and glass-reinforced plastic.Institute of Polymer Mechanics, Academy of Sciences of the Latvian SSR, Riga. Translated from Mekhanika Polimerov, No. 3, pp. 465–475, May–June, 1971.     

Ablation replacement of iron with Co,Mn, Ni,and Cu during growth of iron-based superconductor films in the Fe0.9 M 0.1Se0.92 system

Thin films of iron-based chalcogenide superconductors FeSe_0.92, with iron partially replaced (at least up to 10 at %) by elements such as cobalt, nickel, manganese, or copper, have been grown on the surface of \((10\bar 12)\) LaAlO₃ crystals. Growth is performed by the laser ablation of a target prepared in the form of a ceramic pellet by high-temperature synthesis and the sintering of preliminarily pressed stoichiometric mixture of powders. Iron in these ceramics is replaced with an alloying metal by no more than 3 at %. The rest (7 at %) of the metal is in the form of precipitates of other phases. X-ray diffraction analysis of the grown films has shown that they are single-crystal and free of any precipitates of other crystallographic orientations and phases. This is evidence of the complete (10 at %) replacement of iron with a doping metal in the film structure. This circumstance indicates that the synthesis of components occurs more actively and completely during laser ablation (than in solid-phase chemical reactions) as a result of the transformation of multicomponent target material into plasma. Thus, one can fabricate film materials in a wider range of chemical compositions than in the form of solid-phase synthesized ceramics.     

Plastic Creep Features of Sapphire at Near-Melting Point Temperatures

Crystallography Reports - The anomalous plastic creep of sapphire crystals in the temperature range of 1890–2050°С, which includes their melting point, has been studied. A method...     

Subharmonic Shapiro steps and noise in high-T c superconductor Josephson junctions

An experimental investigation is made of the subharmonic Shapiro steps observed on the I-V curves of high-T _c superconductor Josephson junctions and on the bias-voltage dependences of the rf noise and detector response when the junctions are subjected to external submillimeter radiation. Structures of this type are ordinarily described by a nonsinusoidal current-phase relation, which is why subharmonic steps appear. Numerical modeling of the processes occurring in a Josephson junction by means of a simple current-phase relation, as in the case of an SNS junction, gives good agreement with experiment. The width of the characteristic Josephson generation line of the junction was estimated on the basis of the noise dependences and the selective detector response. The width can be explained by taking into account the shot noise of the tunneling component of the conductivity. A model of the conductivity of a high-T _c superconductor Josephson junction, consisting of a tunnel junction with microshorts possessing metallic conductivity, is discussed. Pis’ma Zh. éksp. Teor. Fiz. 68, No. 5, 426–430 (10 September 1998)     

Growth of YBa2Cu3O7 Films with [100] Tilt of CuO Planes with Respect to the Surface on MgO Crystals

Crystallography Reports - Epitaxial YBa2Cu3O7 films with CuO plane tilted with respect to the surface have been grown on crystalline MgO substrates by pulsed laser deposition. Directly before...     

Anisotropy of High-Temperature Superconductivity in the (100) Plane of YBa2Cu3O7 Film

Crystallography Reports - A film of high-temperature superconductor (HTSC) YBa2Cu3O7 has been grown on the (100) crystallographic plane of SrLaGaO4 crystal using pulse laser deposition. An...     

Temperature sensitivity and noise of an HTSC Josephson detector on a sapphire bicrystal substrate at 77 K

In YBa₂Cu₃O_{7 ? x} films grown on sapphire bicrystal substrates, the Josephson junctions are prepared based on artificial grain boundaries formed by the turn of the crystal lattices about the [100] axis. The films are deposited by the laser ablation method on the buffer CeO₂ layer. The critical film temperature reaches 88.5 K with a transition width of 1.5 K. Junctions from 2 to 3-μ m wide are integrated into the planar log-periodic antennas and their characteristics are measured at 77 K. The characteristic voltage I _c R _n reaches 570 μV. With exposure to external radiation at a frequency of 113 GHz, the Shapiro steps were observed on the current-voltage characteristic. The temperature sensitivity of this detector placed in a quasi-optical receiving unit is measured. At the modulation of the input radiation temperature 77 K/300 K, a response of more than 200 nV is observed at the detector output. At the modulation frequency, intrinsic noise is about 1 nV/Hz^1/2, which corresponds to a temperature resolution of 1 K.     

Resonance states of superheavy hydrogen nuclei obtained in transfer reactions with exotic beams

A resonance state situated at 1.8±0.1 and, most likely, another state positioned at 2.7±0.1 MeV above the t+n+n decay threshold were observed in the missing mass energy spectrum of the ⁵H nucleus produced in the reaction ³H(t,p)⁵H. The peak located close to $E_{^5 H} = 1.8$ MeV also was seen in the ⁵H spectrum obtained from the energy distributions of ³H nuclei emitted in the reaction ²H(⁶He,⁵H)³He. The width (Γ_obs ≤ 0.5 MeV) obtained for the two ⁵H resonance states is surprisingly small. A state of ⁴H with E _res = 3.3 MeV and γ² = 2.3 MeV was obtained in the reaction ²H(t,p)⁴H from the proton spectrum.