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Zhbankov O.,Lesya Ukrainka Eastern European National University | Fedorchuk A.,Lviv National University of Veterinary Medicine and Biotechnologies | Kityk I.,Czestochowa Technological University | Olekseyuk I.,Lesya Ukrainka Eastern European National University | Parasyuk O.,Lesya Ukrainka Eastern European National University
Journal of Alloys and Compounds | Year: 2011

The crystal structure of the ternary compound Ag2SiS3 was determined on the basis of X-ray powder diffraction. The compound belongs to a new structure type, space group P21/c, a = 0.66709(1), b = 0.66567(2), c = 1.31748(3) nm, and β = 118.658(1)°. Ag 2SiS3 contains isolated [Si2S6] anionic units consisting of pairs of edge-shared tetrahedra. The Ag atoms are situated in the interstices formed by these fragments. © 2010 Elsevier B.V. All rights reserved. Source


Avram N.M.,West University of Timisoara | Avram N.M.,Academy of Romanian Scientists | Brik M.G.,University of Tartu | Kityk I.V.,Czestochowa Technological University
Optical Materials | Year: 2010

A detailed microscopic study of the crystal field strength 10Dq for different interionic distances in cubic ZnS:V2+ and MgO:Cr 3+ single crystals was performed. The exchange charge model of crystal field was used to calculate the 10Dq values for different distances between the impurity ions and ligands. The obtained results were extrapolated by the power laws 10Dq ∼ 1/Rn, with n = 4.4208 for ZnS:V 2+ and n = 6.4009 for MgO:Cr3+. With these 10Dq(R) dependencies, a number of important physical quantities describing the optical and dynamical properties of impurity centers (such as the constants of the electron-vibrational interaction, Huang-Rhys parameters, Stokes shifts, Jahn-Teller stabilization energies) were estimated and compared with available literature data. © 2010 Elsevier B.V. All rights reserved. Source


Lakshminarayana G.,Nagoya Institute of Technology | Nogami M.,Nagoya Institute of Technology | Kityk I.V.,Czestochowa Technological University
Journal of the Electrochemical Society | Year: 2010

In this paper, we report on inorganic-organic composite membranes with anhydrous proton conduction prepared by the sol-gel process with tetraethoxysilane/ethyl-triethoxysilane/trimethylphosphate and 1-butyl-3-methylimidazolium-bis(trifluoromethylsulfonyl)imide ([BMI][BTSI]) ionic liquid as precursors. The Fourier transform IR spectroscopy, 31P, 1H, and 13C NMR, and thermogravimetric and differential thermal analysis measurements confirmed that the membranes possess good chemical stability and are thermally stable up to 310°C. Thermal stability was considerably enhanced by the presence of the inorganic SiO 2 framework and the stability of [BTSI] anion. The conductivity of all the fabricated membranes was measured from -30 to 150°C, and a high conductivity of 5× 10-3 S/cm was measured for the 40 wt % [BMI][BTSI] ionic liquid doped membrane at 150°C under anhydrous conditions. The hydrogen permeability was decreased from 1.84× 10-11 to 2.7× 10-12 mol/cm s Pa for the 40 wt % [BMI][BTSI] ionic liquid doped hybrid membrane during temperature increment from 20 to 150°C. For 40 wt % ionic liquid doped hybrid membrane, membrane electrode assemblies were fabricated, and a maximum power density value of 0.17 mW/ cm2 at 0.42 mA/ cm2 as well as a current density of 0.67 mA/ cm2 were achieved at 150°C under nonhumidified conditions. © 2010 The Electrochemical Society. Source


Lakshminarayana G.,Nagoya Institute of Technology | Nogami M.,Nagoya Institute of Technology | Kityk I.V.,Czestochowa Technological University
Energy | Year: 2010

We report on anhydrous proton conducting inorganic-organic composite membranes synthesized from tetraethoxysilane/poly(-dimethylsiloxane)/trimethylphosphate and 1-ethyl-3 methylimidazolium-bis (trifluoromethanesulfonyl) imide ionic liquid as sol-gel precursors. The Fourier transform infrared spectroscopy, 31P, 1H, and 13C Nuclear magnetic resonance, thermo gravimetric and differential thermal analysis measurements confirmed that the prepared hybrid membranes possess good chemical stability and are thermally stable up to 350 °C. Conductivity of all the fabricated hybrid membranes was measured under anhydrous conditions within the temperature range -20-150 °C, and a value of 4.87 × 10-3 S/cm at 150 °C was achieved for 40 wt% [EMI][TFSI] ionic liquid doped 72TEOS-18PDMS-10PO (OCH3)3 (mol %) hybrid membrane. For 40 wt% ionic liquid doped composite membrane, the measured hydrogen permeability value at 150 °C was 4 × 10-12 mol/cm s Pa. © 2010 Elsevier Ltd. Source


Romanyuk Y.E.,Empa - Swiss Federal Laboratories for Materials Science and Technology | Marushko L.P.,European University at Kiev | Piskach L.V.,European University at Kiev | Kityk I.V.,European University at Kiev | And 4 more authors.
CrystEngComm | Year: 2013

While record solar cells based on Cu(In,Ga)Se2 (CIGS) absorbers exhibit the highest conversion efficiencies among all thin film photovoltaic technologies, the structural nature of the electronically favourable heterojunction CIGS-CdS is still debatable. Here, we present an investigation of the phase equilibria in the full Cu(In,Ga)(S,Se)2-2Cd(S,Se) quaternary exchange system at the selected annealing temperature of 870 K in order to reveal the formation of intermediate solid solutions. There are three single phase regions in the system: the chalcopyrite α-solid solution based on Cu(In,Ga)(S,Se)2, the wurtzite β-solid solution of Cd(S,Se), and the intermediate γ-solid solution existing in a zinc blende structure. The γ-phase has a broad homogeneity range and crystallizes in the cubic space group F43m with a statistical distribution of metal atoms in the cation sub-lattice. © 2013 The Royal Society of Chemistry. Source

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