Study Of Electrophysical Properties Research Articles

"IMPROVING THE ELECTROPHYSICAL PROPERTIES OF NANOCOMPOSITE MATERIALS BASED ON GRAPHENE OXIDE AND TIO2"

"This article shows the results related to the study of the effect of graphene oxide on the photoelectric properties of nanostructured titanium dioxide films. A TiO2–GO nanocomposite material with a graphene oxide concentration of 3 wt% was synthesized by hydrothermal method. The Raman and IR spectra of nanocomposite materials have been studied and show the presence of peaks characteristic of graphene oxide and titanium dioxide. In the IR spectra, the so-called Ti-O-C bond is observed, which is responsible for fluctuations between TiO2 and graphene oxide. Studies of absorption spectra show that in a nanocomposite material, the absorption spectrum is shifted to the long-wavelength region of light. Studies of electrophysical properties were carried out using electrochemical impedance spectroscopy. The impedance spectrum of this material shows that there is an improvement when graphene oxide is added to TiO2 films. Photovoltaic parameters also show an increase in the photoinduced current in a nanocomposite material with the addition of graphene oxide by 3 wt%. It is shown that when graphene oxide is added 3 wt% to TiO2, an increase in photocatalytic properties is observed due to an increase in the photoinduced current of the nanocomposite material. "

Протонпроводящая керамика на основе гафната и церата бария, легированных оксидами циркония, иттрия и иттербия для электролитов топливных элементов

Nanopowders of the compositions BaHf1 – xYbxO3 – δ (x = 0.04; 0.08; 0.10) and BaCe0.9 – xZrxY0.1O3 – δ (x = 0; 0.5; 0.6; 0.7 and 0.8) were synthesized by the combined crystallization and nitric acid salts using the citrate-nitrate method. Those nanopowders were used to produce ceramic materials with a cubic crystal structure of the perovskite type, with a grain size of ~ 20 – 70 nm. The study of electrophysical properties revealed that they have a proton type of conductivity in the temperature range of 500 – 700 °C; σ = 10–2 – 10–5 Cm/cm. Type and mechanism of electrical conductivity of ceramics of the composition BaHf1 – xYbxO3 – δ (x = 0.04; 0.08; 0.10) have been studied both experimentally and using theoretical calculations-by computer modeling using the electron density functional method; the results are in good agreement. The research shows the prospects of using the obtained ceramic materials as proton-conducting electrolytes of solid-oxide fuel cells.

Concentration and Size Effects in Electrophysical Properties of Thin Films Based on Permalloy and Silver

Complex study of electrophysical properties (the electrical resistivity r and the temperature coefficient of resistance (TCR) b) of thin-film samples based on ferromagnetic alloy Ni80Fe20 (permalloy) and noble metal Ag in a wide composition range and within the range of thickness 20-100 nm done. Thin films were obtained by the method of electron-beam co-evaporation technique at room temperature. Their composition was investigated using the method of X-ray spectrometry. The phase state was analyzed by the electron diffraction method. It was demonstrated that the crystal structure of thin films stays unchanged during the annealing process to 500 K. The size and concentration dependences of r and b values were obtained. The corresponding maximum and minimum at the concentration of Ag atoms of 50-60 at.% observed at the dependences r(cAg) and b(cAg). Size dependences r(d) and b(d) associated with the size effects in thin-film materials.

THE STUDY OF THE ELECTROPHYSICAL PROPERTIES OF A COMPOSITE MEMRISTOR-DIODE CROSSBAR AS A BASIS OF THE NEUROPROCESSOR HARDWARE IMPLEMENTATION

The aim of this article lies in checking the efficiency of memory and logic matrices. Achieving this has required producing a composite memristor-diode crossbar and studying its electrophysical properties. For these purposes, the authors have made a measuring bench, which consists of a composite memristor-diode crossbar, control peripheral circuitry, based on discrete elements with CMOS logic, and Keithley SourceMeter 2400. The silicon junction p-Si/n-Si has been chosen because its electrical properties better suit the Zenner diode’s requirements compared to the p-Si/ZnO junction. The memristor-diode crossbar with the TiN/Ti0,93Al0,07Ox/p-Si/n-Si/W structure was made with implementation of a new diode. The results show that the crossbar cell with a p-Si/n-Si diode has better rectifying properties in comparison with a p-Si/ZnOx diode, because the current in the crossbar cell with positive voltage bias is much higher than with negative voltage bias. Strong rectifying properties of the cell are necessary for the functioning of diode logic in the logic matrix and for memristor state recording in the logic and memory matrices. The study of electrophysical properties of the composite memristor-diode crossbar, measurement of current-voltage characteristics of the diode and composite memristor-diode crossbar cell and signal processing were performed. The signal processing was performed in the following modes: addition of output impulses of neurons and their routing to synapses of other neurons; multiplication of number matrix by vector, performed in the memory matrix with weighing and totalling of signals; and associative self-learning. For the first time, the generation of a new association (new knowledge) in the composite memristor-diode crossbar has been shown, as opposed to associative self-learning in existing hardware neural networks with discrete-memristors-based synapses. The change of crossbar cell’s output current caused by parasitic currents through adjacent cells has been determined. The results show that the control over Zenner diode characteristics allows reducing the power consumption of the composite crossbar. Obtained electrophysical characteristics prove the efficiency of the composite memristor-diode crossbar, intended for production of the memory and logic matrices.

Electrophysical properties of granular film alloys

The results of experimental researches of the structure and phase state and electrophysical properties of the double-component film systems based on Co and Cu or Ag, Fe and Cu, in which the granular solid solutions (s.s.) are presented. The formation of granular films was carried out as a layer condensation of superfine layers (d ≈ 0.5–3 nm) with subsequent annealing up to 850 K, and simultaneous condensation of separate components. With a total thickness of films up to 60 nm, the average size of Co magnetic granules is 3–7 nm. Parameters of the fcc lattice of a granular s.s. is a = 0.408–0.409 nm (based on Ag and Co) and a = 0.358 nm (based on Cu and Co). In multilayer films based on α-Fe and Cu formed s.s. based on α-Fe (at 1.5<dFe<2 nm) or s.s. based on Cu (at dFe<1.5 nm) with lattice parameters which are very close to the α-Fe or Cu parameter. Studies of electrophysical properties indicate that the resistivity depends to a large extent on the total concentration of the magnetic component and the temperature of the measurement. The value ρ in thermostabilized films is (1–4) × 10−7 Ω × m, and the value of the thermal coefficient of resistance β≈(0.5–1.5) × 10−3 K−1 does not depend from the samples thickness, temperature and the concentration of the magnetic component.

Electromagnetic and mechanical properties of nanocomposites polyacrylonitrile/carbon nanotubes

The films of carbon-polymer nanocomposite PAN/SWCNT with different filler concentrations, varying from 0.5 to 30 wt.%, are synthesized. It found that the use of fillers in the polymer composite on the basis of PAN, in the form of SWNTs, significantly affects the mechanical properties of the polymer, in particular, the tensile strength increases. The study of electrophysical properties showed that when SWNT fillers are introduced from 0.5 to 30 wt.%, the electrical conductivity increases by 2 orders of magnitude due to the increase in the percolation degree and by 7 orders of magnitude in comparison with pure PAN. The dielectric constant and reflectance (R), transmission (T), absorption (A) in the terahertz range are measured. It found that the reflection coefficient is nonlinearly dependent on the concentration of carbon nanotubes, and the minimum reflection coefficient is 0.55 a.u. is observed at a concentration of 0.5 wt.%, while materials with a SWNT concentration of more than 5 wt.% show almost identical reflection coefficient at a sufficiently low transmission factor.

The physical basis of the fabrication of the third generation of high-temperature superconducting wires on quartz substrates

The problem of the fabrication of third-generation high-temperature superconductors (HTSCs) that are designed for the transmission of electric energy and the creation of nanoelectronic devices is studied in this work. The issues of the fabrication of dielectric substrates for the third generation wires are considered. The technology of HTSC film deposition on the quartz substrates is presented. Complex studies of sputtering of the buffer and superconducting YBa2Cu3O7 − δ (YBCO) layers were performed. The results of studies of electrophysical properties of the HTSC films on the quartz substrates are discussed.

Growth of KTiOPO4 crystals doped with zinc and studies of their physical properties and specific structural features

A series of potassium titanyl phosphate single crystals doped with zinc (KTP: Zn) is grown by spontaneous flux crystallization. Their properties and the way the additive is implanted in the crystal lattice are studied. The inclusion of zinc atoms in the KTP structure is evidenced by the data of chemical analysis and the results of studies of electrophysical properties (the growth of conductivity and increase of relaxation anomalies). Precision X-ray diffraction studies of KTP: Zn single crystals reveal changes in the channel of the structure which correlate with the physical properties of this crystal series. No substitution of zinc atoms for titanium, phosphorus, or potassium atoms is found in the structure. Zinc atoms can be located at structural defects, domain walls, and the crystal surface.

Effect of electron irradiation on InSb microcrystals

The results of experimental studies of electrophysical properties of heavily doped n-InSb whiskers exposed to electron irradiation (13 MeV, 300 K) are reported. The limiting electrophysical parameters and the problem of the Fermi-level pinning in irradiated InSb are discussed.