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  • Dielectric and polarization properties of SrTiO3-based quantum paraelectrics

    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

  • Preparation and study of the optical properties of arrays of Au nanoparticles on the surface of thin films of ZnO

    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

  • UV photodetector based on nanorods and zinc oxide films

    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

  • Investigation of ZnO nanorods by photoluminescence technique for optimization characteristics of sensitive element SAW of CO sensor

      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

  • Investigation of influence of adsorbtion of CO on characteristics of hold-up line on SAW with ZnO nanorods sensitive element

    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