V Bakul Institute For Superhard Materials

Kiev, Ukraine

V Bakul Institute For Superhard Materials

Kiev, Ukraine
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Ievtushenko A.I.,Frantsevich Institute for Problems of Materials Science | Lashkarev G.V.,Frantsevich Institute for Problems of Materials Science | Lazorenko V.I.,Frantsevich Institute for Problems of Materials Science | Karpyna V.A.,Frantsevich Institute for Problems of Materials Science | And 8 more authors.
Physica Status Solidi (A) Applications and Materials Science | Year: 2010

Investigations of photoelectrical properties of ZnO films are important scientific task for designing UV detectors for various applications. We report the positive role of nitrogen doping in increasing photoresponsivity of ZnO:N-based detectors. It is suggested that nitrogen slightly deteriorates the structural quality of ZnO films and compensates intrinsic defects that increase photoresponsivity. Also, the spectral response of Ni/ZnO:N/n+-Si structures at different biases were considered. (Graph presented). © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Ivashchenko V.I.,Ukrainian Academy of Sciences | Pogrebnjak A.D.,Sumy National University | Sobol' O.V.,Kharkiv Polytechnic Institute | Rogoz V.N.,Sumy National University | And 3 more authors.
Technical Physics Letters | Year: 2015

Nanocomposite films based on (Nb2Al)N intermetallic nitride have been obtained by the method of magnetron sputtering. X-ray diffraction analysis revealed two stable states of the crystalline structure: (i) NbN with low amount (within 5 at %) of dissolved Al in a composition close to (Nb2Al)N and (ii) an amorphous component related to aluminum nitride formed by reactive magnetron sputtering. The substructural characteristics (grain size and microdeformation level) are sensitive to the current via Al target and exhibit correlation with nanohardness and Knoop hardness of the film, which vary within 29–33.5 and 46–48 GPa, respectively. © 2015, Pleiades Publishing, Ltd.

Krivosheya A.,V Bakul Institute For Superhard Materials | Danilchenko J.,Kharkiv Polytechnic Institute | Storchak M.,University of Stuttgart | Pasternak S.,University of Stuttgart
Mechanisms and Machine Science | Year: 2016

The development and manufacturing of gear pairs is determined by a system combining the kinematic basis of the relative motions between workpiece and tool with the necessary production technology. This system unites the two subsystems of theory and technology. Via a multitude of parameters, gears can be assigned to different classes according to the range of existence. The paper describes a mathematical model for determining the range of existence for the general kinematic scheme of gear shaping. This model is based on an analysis of the existing kinematic schemes of theoretical and real shaping. Based on a morphological approach, individual kinematic shaping schemes are classified, and their mathematical models are developed. The shaping schemes, as well as the necessary translational and rotational motion matrices, are exemplarily presented for a gear manufacturing machine using the shaping principle. The modern approaches to the principles of designing equipment and instrumentation systems for gear manufacturing are presented. Methodical basics for selecting the optimal machine configuration depending on the technical and economic requirements for the machining and form of a gear’s tooth profile are stated. The system for theoretical and technological optimization synthesis of instrumentation systems for gear manufacturing is presented. © Springer International Publishing Switzerland 2016.

Shaternik V.,NASU G.V. Kurdyumov Institute For Metal Physics | Shapovalov A.,NASU G.V. Kurdyumov Institute For Metal Physics | Shapovalov A.,V Bakul Institute For Superhard Materials | Belogolovskii M.,Donetsk Institute for Physics and Engineering | And 4 more authors.
Materials Research Express | Year: 2014

We have fabricated trilayered sandwiches consisting of superconducting electrodes made of MoRe alloy with a critical temperature of about 10K and a silicon interlayer of thicknesses up to 20 nm doped by tungsten with atomic concentrations up to 10 at%. For concentrations below 5 at%, measurements of transport characteristics have revealed the presence of charging energy in ultrasmall dopant granules (the Coulomb-blockade effect) without any supercurrent through the junction. Unexpectedly, a persistent current at zero voltage bias has exposed itself at higher W concentrations and even for the thickest W:Si layers. Microwave-radiation experiments have proven that in this case we are dealing with a Josephson current. The observation is explained as the fingerprint of 'open' channels in the charge transmission due to resonance-percolating trajectories inside the strongly inhomogeneous silicon interlayer with metallic nanoclusters. We have calculated the ratio of super-and excess currents using a universal distribution function for randomly arranged localized states and found good agreement with our experimental data without any adjustable parameters. The novel functionalities due to the disorder in doped semiconducting films make it possible to fabricate trilayered junctions with enhanced conductance properties and, at the same time, with well separated metallic electrodes. © 2014 IOP Publishing Ltd.

Yao H.,Harbin Institute of Technology | Li Z.,Harbin Institute of Technology | Zhao X.,Harbin Institute of Technology | Sun T.,Harbin Institute of Technology | And 2 more authors.
International Journal of Advanced Manufacturing Technology | Year: 2016

Ultra-precision machining has been widely used in the manufacturing of optical components. Volumetric error analysis and error compensation are essential issues that must be considered to improve the accuracy of the machining process. However, analysis of the effects of kinematics errors on surface generation by ultra-precision machining using a swing arm ultra-precision diamond turning machine (SA-UDTM) and the alignment methods required have received little research attention to date. This paper presents the development of a kinematics error model of the SA-UDTM that accounts for geometric errors by simplifying the machining system and considering it as a rigid multi-body system. Then, the main error contributions to the processing precision can be derived from sensitivity analysis of error components. Finally, an alignment method is developed to reduce or eliminate the corresponding positioning errors of the mechanical system and thus improves the form accuracy of processed surface. To verify the theoretical kinematics model and the proposed alignment method, a series of contrast machining experiments have been performed, and the experimental results indicate that the proposed method is effective. © 2016 Springer-Verlag London

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