The doelectric and polarization studies of the system of solid solutions PbxSr1-xTiO3 with x = 0.005, 0.02, 0.04 in a broad frequency and temperature range are performed. The temperature of the ferroelectric phase transition in the solid solutions is determined. The temperature behaviour of the remanent polarization at the phase transition is established.

Keywords: quantum paraelectric, strontium titanate, dielectric permittivity, remanent poalrization, superparaelectric state, phase transition

The structure of synthesized ferroelectric samples of PbSc0.5Ta0.5O3 after mechanoactivation were studied by means of X-ray absorption spectroscopy(XANES), X-ray diffraction (XRD) and scanning electron microscopy (SEM). Based on the combination of effective experimental methods and computer modeling of theoretical X-ray absorption spectra near the L3 - edge of tantalum and lead was studied character of structural distortions for investigated samples after mechanoactivation.

Keywords: Ferroelectrics materials, mechanoactivation, XANES, defects

Research of possibility of management of morphological parameters of arrays nanoparticles Au (form, the size, density of superficial distribution) of the thin films of ZnO received on a surface by method of the pulse laser deposition (PLD) with subsequent annealing in the inert atmosphere was conducted. It was experimentally established that increase of the average size of Au nanoparticles leads to the plasmon peak broadening and its shifting to the red region. Nanoparticles with diameters 17, 25, 31, 37 and 40 nm have plasmon absorption maximums at wavelengths 570, 590, 605, 610 and 620 nm, respectively. With the increase of the average nanoparticle size nm to a certain value rise of maximum in absorbtion spectra at wavelengths 570, 590, 605 and 610 followed by its decrease at 620 nm is observed. The highest value of the intensity at/in the absorption maximum corresponds to the average diameter of the nanoparticles of 37 nm. Optimal conditions for synthesis of isolated arrays of Au nanoparticles on the surface of ZnO thin films with high maximum of plasmon absorption were experimentally found. Obtained results can be used to increase the sensitivity of the photodetectors and solar cells based on zinc oxide or chemosensors based on Raman amplification effect near the gold nanoparticles.

Keywords: nanoparticles of Au, arrays of isolated nanoparticles, plasmon resonance, a photodetector, photosensitivity, ZnO film

In the present study, platinum was electrodeposited onto rotating disc electrode coated with Vulcan XC-72R Nafion suspension and uncoated smooth glassy carbon electrode from acidic solution of 5mМ H2PtCl6. The electrochemically active surface area of platinum particles obtained was determined by cyclic voltammetry and the structural characteristic of the particles was studied by scanning electron microscopy. The impact of current and time on the electrochemically active surface area of platinum particles electrodeposited on the carbon supports was also investigated and described in this paper. The present work is expected to be utilized and contribute to the improvement of electrochemically active surface area of platinum catalysts for low temperature fuel cells.

Keywords: galvanostatic electrodeposition, chronopotentiometric curves, chloroplatinic acid, vulcan XC-72R, fuel cells

With the use of pulsed laser deposition and carbothermal synthesis а photosensitive structure on the basis of the Schottky barrier Au/ZnO(nanorods)/ZnO(film)/ZnO(nanorods)/Au was obtained. The parameters of the carbothermal method of synthesis of nanorods ZnO were optimized. Under directly applied bias of 7V current sensitivity of luminous flux for this photodetector is observed in the UV and visible regions of the spectrum, and is 0.14 A/W - for 325 nm and 0.18 A/W - to 405 nm, which means that this structure has the ability of potential applications in various fields for the control of UV radiation (for example, for the monitoring of solar UV radiation, control of UV radiation in air and disinfecting water devices).

Keywords: ZnO nanorods, Schottky barrier, photodetector, photosensitivity

ZnO nanorod arrays have been synthesized on silicon wafers by chemical vapor deposition (CVD) technique with different  temperature modes, without metal catalyst.  With this method   vertically aligned ZnO nanostructures  were grown at the quite low temperatures.  Modification of the method allowed to place silicon substrates in areas with different  ratios of concentrations of the molecules in the vapor phase. Photoluminescence spectroscopy and electron microscopy studies have shown that morphologies and optical properties of nanorods depends on different ratios of concentrations of the molecules in the vapor phase.

Keywords: ZnO nanorods,chemical vapor deposition (CVD), photoluminescence

The arrays of ZnO nanorods were obtained on the sapphire substrates by means of pulsed laser deposition under the high pressure of argon. The conditions of synthesis were optimized, and their influence on the morphology of  ZnO nanostructures were revealed. It is shown that the concentration of oxygen vacancies in ZnO nanorods can be changed by regulation of the synthesis temperature from 850 to 915 °. This process can be controlled by the ratio of intensities of the photoluminescence emission in the visible and ultraviolet regions. So, it allows to create nanostructures for UV photodetectors or chemosensors depending on the temperature choice.

Keywords: ZnO nanorods, laser deposition, PLD, photoluminescence

Information about authors of issue №4 (2013)

Keywords: authors

  Sensitive element of CO sensor was created by pulsed laser deposition and it was integrated in device of surface acoustic waves (SAW). Photoluminescence was used to control of oxygen-related defects of ZnO nanorod arrays. It is shown that the deficiency of oxygen in zinc oxide nanorods can be increased by change in temperature synthesis of nanorods of 850 to 915 ° C with a high argon pressure, and control of the deficiency of oxygen by increasing the ratio of the intensity of radiation in the visible region of the luminescence intensity in the ultraviolet region of the spectrum can help to increase the sensitivity of CO.

Keywords: ZnO nanorods, photoluminescence, CO sensor

Structure of  surface acoustic waves(SAW) of CO sensor was developed. SAW sensor include transceiving IDT and catoptric IDT, which is loaded on the impedance of ZnO nanorods. Peak of reflection SAW from IDT clearly observed as result Fourier transformation of time function of pulsed response. IDT loaded on resistance paralleled ZnO nanorods, which depends on the concentration of CO.

Keywords: ZnO nanorods, device on SAW, CO sensor

The sensor design on surface acoustic waves (SAW), representing the delay line with unidirectional inter-digital transducers (IDT) is considered. The factor of reflection of SAW from the unidirectional IDT loaded on impedance depending on value of resistance connected to it is investigated. On dependence of factor of reflection on size of resistance there is almost linear site at values of resistance more than 50 Ohm. The new design of the connected lattices of nanowire of zinc oxide, having the general resistance in a range of 50-250 Ohm which is connected to reflective IDT as loading is developed.

Keywords: passive sensors, ZnO nanowire, surface acoustic waves, interdigital transducer.

Information about authors of issue №4 p.1 (2012)

Keywords: authors

Carbothermal synthesis method on substrates of a-Al2O3 thin film with sublayers ZnO: Ga, using copper as a catalyst for the arrays obtained by varying the zinc oxide rod morphology. It was established that growth of the rods occurs direction perpendicular to the substrate using a thin (~ 1 nm) layers of the catalyst. With increasing thickness of the catalyst layer to 3 nm rods growth occurs at an angle to the surface of the rod with a mutual orientation in the plane of the substrate surface at angles that are multiples of 60 °. Also, the selectivity demonstrated growth ZnO rods arrays on portions of the substrate coated with the catalyst.
Keywords: zinc oxide, micro - and nanorods carbothermic synthesis method, film sublayer growth catalyst.

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In the present work we have carried out studies of the processes of growth of zinc oxide nanorods by hydrothermal method on silicon substrates. As sublayer catalyst used growth caused by laser deposition of zinc oxide, various thicknesses. Studied selective growth of nanorods on the microstructure of thin-film sub-layers of zinc oxide obtained by laser deposition. The optimal conditions for the synthesis of: the concentration of Zn (NO3) 2 - 0.4 mol / l, hexamethylenetetramine - 0.4 mol / l, the concentration of NH3 · H2O - 0,01 mol / L -0.01, process time 4:00, the process temperature is 80 ° C. Sublayer thickness of zinc oxide, as shown by experiment, the growth of the rods has no noticeable effect. Oriented arrays of nanorods were obtained up to 500 nm and a diameter of 60-150 nm.
Keywords: zinc oxide nanorods and micro-oriented arrays of nanorods, hydrothermal synthesis method, selective growth, thin film underlayer.

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