Eastern Ukrainian University

Luts’k, Ukraine

Eastern Ukrainian University

Luts’k, Ukraine

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Ozga K.,Czestochowa University of Technology | Lakshminarayana G.,Los Alamos National Laboratory | Szota M.,Czestochowa University of Technology | Nabialek M.,ugosh University Czestochowa | And 6 more authors.
Optical and Quantum Electronics | Year: 2013

The occurrence of linear electrooptics and optical anisotropy is observed in the ferroic crystals [ NH2(C2H5) 2]2CuCl4 embedded into polymethylmethacrylate polymer matrix. The studies were performed for the optically treated bulk crystals and the large-size nanocrystals (with sizes higher than 50 nm) embedded into the polymer matrix. The specimens were both in a form of bulk as well as in the form of the composite films. To understand the mechanisms giving the principal role to the effect we have performed polarized absorption measurements for the samples treated in the external dc-electric field and bicolour 532 nm/1,064 nm laser treatments. The behaviour of the birefringence and of the linear electrooptics coefficients were studied within a temperature range covering the incommensurate phase existence. © 2013 Springer Science+Business Media New York.


Rao M.S.,Acharya Nagarjuna University | Sudarsan V.,Bhabha Atomic Research Center | Brik M.G.,University of Tartu | Gandhi Y.,Kakani Venkata Ratnam College | And 5 more authors.
Journal of Alloys and Compounds | Year: 2013

Emission features of Dy3+ ions were characterized as a function of Al2O3 concentration in lead silicate glasses. The emission spectra exhibited conventional blue, yellow, orange and red emission bands due to 4F9/2?6H15/2, 6H13/2, 6H11/2 and 6H9/2 transitions of Dy3+ ions, respectively. The intensity of all these bands exhibited increasing trend with increase in the concentration of Al2O3 and this increase was attributed to decrease of luminescence quenching due to declusterization of Dy3+ ions by Al3+ ions in the glass network. From the emission spectra, the radiative parameters viz., spontaneous emission probability A, the total emission probability AT, the radiative lifetime τρ, the fluorescent branching ratio b, of different transitions originated from 4F9/2 level of Dy3+ ions were evaluated. The Y (I4F9=2→6H11/2)=B(I4F9/2→6H15/2) integral emission intensity ratio of Dy3+ ions evaluated from the luminescence spectra, showed decreasing trend with increase in the concentration of Al2O3. The decrease of this ratio is explained basing on structural modifications taking place in the vicinity of the Dy3+ ion in the glass matrix. The CIE color coordinates for three glasses were evaluated and found to be in the yellow region. © 2013 Elsevier B.V. All rights reserved.


Kassab L.P.R.,São Paulo State Technological College | Camilo M.E.,University of Sao Paulo | De Assumpcao T.A.A.,University of Sao Paulo | Myronchuk G.L.,Eastern Ukrainian University
Journal of Non-Crystalline Solids | Year: 2013

A novel method of preparation of the Si nanoparticles (NPs) incorporated in tellurite TeO2-WO3-Bi2O3 (TWB) thin films is proposed. This mew method applies RF magnetron sputtering technique at room temperature. The incorporation of Si NP was confirmed by transmission electron microscopy (TEM); isolated Si NPs with diameters of around 6 nm are observed. Energy dispersive X-ray spectroscopy (EDS) was performed during TEM analysis in order to confirm the presence of Si NP and also the other elements of the thin film. The thin films are explored with respect to the photoinduced changes of the reflectivity within the 400-65 nm spectra range using a 10 ns pulsed Nd:YAG with power densities varying up to 400 MW/cm2 and beam diameter within the 3-5 mm range. The observed processes are analyzed within a framework of trapping level conceptions for the Si NP. The possible application of the discovered materials as optical sensitive sensors is proposed. © 2013 Elsevier B.V.

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