Piasecki M.,ugosh University |
Myronchuk G.,Lesya Ukrainka Eastern European National University |
Lakshminarayana G.,Los Alamos National Laboratory |
Reshak A.H.,University of South Bohemia |
And 4 more authors.
Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy | Year: 2012
Complex spectral studies of near-band gap and photoconductive spectra for novel Ag 2In 2SiS 6 and Ag 2In 2GeS 6 single crystals are presented. The spectral dependences of photoconductivity clearly show an existence of spectral maxima within the 450 nm-540 nm and 780 nm-920 nm. The fundamental absorption edge is analyzed by Urbach rule. The origin of the spectral photoconductivity spectral maxima is discussed. Temperature dependences of the spectra were done. The obtained spectral features allow to propose the titled crystals as photosensors. An analysis of the absorption and photoconductivity spectra is given within a framework of oversimplified spectroscopic model of complex chalcogenide crystals. © 2012 Elsevier B.V. All rights reserved.
Parasyuk O.V.,Lesya Ukrainka Eastern European National University |
Myronchuk G.L.,Lesya Ukrainka Eastern European National University |
Fedorchuk A.O.,Lesya Ukrainka Eastern European National University |
El-Naggar A.M.,Ain Shams University |
And 5 more authors.
Crystals | Year: 2016
We have discovered a substantial enhancement of the piezoelectric coefficients (from 10 to 78 pm/V) in the chalcogenide Ag2Ga2SiS6 single crystals. The piezoelectric studies were done under the influence of a CO2 laser (wavelength 10.6 µm, time duration 200 ns, lasers with power densities varying up to 700 MW/cm2). Contrary to the earlier studies where the photoinduced piezoelectricity was done under the influence of the near IR lasers, the effect is higher by at least one order, which is a consequence of the phonon anharmonic contributions and photopolarizations. Such a discovery allows one to build infrared piezotronic devices, which may be used for the production of the IR laser tunable optoelectronic triggers and memories. This is additionally confirmed by the fact that analogous photoillumination by the near IR laser (Nd:YAG (1064 nm) and Er:glass laser (1540 nm)) gives the obtained values of the effective piezoelectricity at of least one order less. The effect is completely reversible with a relaxation time up to several milliseconds. In order to clarify the role of free carriers, additional studies of photoelectrical spectra were done. © 2016 by the authors; licensee MDPI, Basel, Switzerland.
Krishnakumar V.,Periyar University |
Nagalakshmi R.,National Institute of Technology Tiruchirappalli |
Manohar S.,Periyar University |
Piasecki M.,ugosh University |
And 2 more authors.
Physica B: Condensed Matter | Year: 2010
Good quality single crystals of a complex between urea and resorcinol (UR-C 6H 5O 2 -:(NH 2)CO(NH 3) +) in the ratio (1:1) have been grown by low temperature solution growth technique using acetone and a mixture of acetone and water (1:1). The solubility studies have been carried out in both the solvents at various temperatures. The X-ray diffraction studies show that the complex crystallized in orthorhombic space group P2 12 12 1. The linear electro optical, piezooptical and second harmonic generation measurements were performed. The results obtained in these studies were discussed in detail. The optical transparency window observed in the visible and near IR regions recommends the crystal for nonlinear optical applications. Dependence of the effective second order optical susceptibility on time of simultaneously applied dc-electric field and UV-treatment were performed and discussed. © 2009 Elsevier B.V. All rights reserved.
Douayar A.,Mohammed V University |
Belayachi A.,Mohammed V University |
Abd-Lefdil M.,Mohammed V University |
Nouneh K.,Innovation and Research Foundation |
And 5 more authors.
Journal of Alloys and Compounds | Year: 2013
The photoinduced linear electrooptical effect was measured using the bicolor laser light between the fundamental 10 ns Nd:YAG laser beam and its green doubled frequency. The optimal ratio of intensities between these two beams was equal to 5:1. As a probing beam, it was used cw 12 mW He-Ne laser beam and Senarmont method was used for detection of the birefringence with accuracy of 10-6. The studies were done on zinc oxide nanocrystalline films doped by Tm3+ ions. Maximal linear EO changes were obtained at minimal Tm3+ content equal to about 0.1% in weight units. With the further increase of the photoinducing beam the observed EO effect enhancement is not so evident and for the 0.5% of Tm3+ the effect disappears at all times during the illumination. The obtained results show that a principal role of localization of the rare earths in the observed effects may be a consequence of formation of the charge density non-centrosymmetry which is crucially dependent on the Tm3+ content in ZnO films. © 2012 Elsevier B.V. All rights reserved.