Microwave binstability in a planar ferrite-piezoelectric resonator

Bistability in a planar resonator containing an iron-yttrium garnet ferrite film and a lead zirconate titanate (PZT) plate is studied. The characteristics of the bistable resonator are measured in a frequency band of 0.8–16 GHz at an excitation power level ranging from 1 to 20 mW. Magnetic and electric tuning of the resonator frequency and switching of the resonator between stable states with the use of weak magnetic (∼0.5 Oe) and electric (0.75 kV/cm) fields are demonstrated. It is shown that, as the excitation power increases, the resonator’s switching time decreases from ∼1.7 to ∼0.3 μs.     

Optical properties and structure of laser crystals Cr: Mg2SiO4 after irradiation

At the present time the ionizing radiation is broadly used for modification ofproperties various materials, including elements of the quantum electronics.     

Pulsed laser reshaping and fragmentation of upconversion nanoparticles — from hexagonal prisms to 1D nanorods through “Medusa”-like structures

One dimensional (1D) nanostructures attract considerable attention, enabling a broad application owing to their unique properties. However, the precise mechanism of 1D morphology attainment remains a matter of debate. In this study, ultrafast picosecond (ps) laser-induced treatment on upconversion nanoparticles (UCNPs) is offered as a tool for 1D-nanostructures formation. Fragmentation, reshaping through recrystallization process and bioadaptation of initially hydrophobic (β-Na_1.5Y_1.5F₆: Yb³⁺, Tm³⁺/β-Na_1.5Y_1.5F₆) core/shell nanoparticles by means of one-step laser treatment in water are demonstrated. “True” 1D nanostructures through “Medusa”-like structures can be obtained, maintaining anti-Stokes luminescence functionalities. A matter of the one-dimensional UCNPs based on direction of energy migration processes is debated. The proposed laser treatment approach is suitable for fast UCNP surface modification and nano-to-nano transformation, that open unique opportunities to expand UCNP applications in industry and biomedicine.

     

The Influence of Equal Channel Angular Pressing on Structure and Mechanical Properties of New β-Ti Alloy Ti–10Mo–8Nb–6Zr

Russian Journal of Non-Ferrous Metals - This work presents comparative studies of structural and mechanical properties of a new β-Ti alloy Ti–10Mo–8Nb–6Zr exposed to...     

Effect of low temperature on plastic deformation in structural materials in a complex state of stress

The results of experimental studies of elastoplastic deformation in structural materials of different grades in a complex state of stress at low temperatures are analyzed. It is shown that the degree of the effect of temperature and force conditions on the character of materials’ strain hardening at low temperature depends on their nature and structural state. The principal hypotheses and postulates that form the basis of the modern plasticity theories are examined for low temperatures. Two new models are introduced to describe the elastoplastic deformation of quasi-brittle and metastable materials under the simple loading with consideration for the effect of low temperatures on their structural state and mechanical properties.     

Pulsed ARC heat treatment of metal surfaces

The treatment of a metal surface by an arc discharge of a capacitor bank is characterized by low relative cost of the equipment, the possibility of alloying the surface from a gas medium, low consumption of power, and environmental safety, which makes the method advantageous for industrial use. It provides cooling of the heated surface at the same rate as in beam surface treatment. The present paper concerns the role of the process factors in optimization of the results of pulsed arc treatment, i.e., in decreasing the damage to the surface, increasing the depth of the structural changes, and obtaining maximum hardness for the surface layer. Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 6, pp. 8–12, June, 1998.     

Growth of GaN by molecular-beam epitaxy with activation of the nitrogen by a capacitive rf magnetron discharge

It is shown that GaN films can be grown by molecular-beam epitaxy with plasma activation of the nitrogen by a magnetron rf discharge in a specially constructed coaxial source with capacitive coupling. A growth rate of ∼0.1 μm/h is obtained on GaAs and sapphire substrates, and ways are found for optimizing the design of the plasma source in order to increase the growth rate. The electrophysical and luminescence properties of undoped epitaxial films are investigated at temperatures ranging all the way to room temperature. Pis’ma Zh. Tekh. Fiz. 24, 30–35 (June 26, 1998)     

Studying the Sensitivity of Graphene for Biosensor Applications

Technical Physics Letters - We have studied the response of graphene-film-based chips on SiC substrates (the relative change in the chip resistance) to coming into contact with fluorescein...