Wyniki wyszukiwania - Biblioteka Nauki

1

Structural properties of Sb- and Te-based binary compounds: Spin-orbit effect

100%

Al-Douri Y.

Materials Science Poland

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2013

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tom Vol. 31, No. 1

133-138

EN

The band structure of AlSb, GaSb, ZnTe and CdTe is calculated using the empirical pseudopotential method (EPM) coupled with spin-orbit (SO) splitting. We applied our empirical model of bulk modulus with SO effect. It has been noticed that SO has a crucial effect on the band structure of these compounds but does not in?uence the structural phase transition. The calculated results are in good agreement with the experimental data.

2

Structural and optical properties of nanostructured bismuth oxide

100%

Ali R. S.

International Letters of Chemistry, Physics and Astronomy

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2014

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tom Vol. 15

64--72

EN

Thin films of bismuth oxide have been prepared utilizing vacuum evaporation. XRD anyalysis reveal that all the films were tetragonal polycrystalline structure with a preferred orientation along (002) plane. SEM images indicate that the grain size fall in the category of nanosize. AFM results assure that the nanonstructure behavior of thin films. Optical studies show that these films have a direct transition with optical energy gap equal to 2.5 eV.

3

Structural and electrical properties of barium titanate (BaTiO3) thin films obtained by spray pyrolysis method

100%

Kumbhar S. S. , Mahadik M. A. , Chougule P. K. , Mohite V. S. , Hunge Y. M. , Rajpure K. Y. , Moholkar A. V. , Bhosale C. H.

Materials Science Poland

|

2015

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tom Vol. 33, No. 4

852--861

EN

Barium titanate (BaTiO3) thin films have been prepared using the spray pyrolysis method. The films were deposited onto a glass substrate at varying substrate temperature ranging from 250 to 350 degrees C with the interval of 50 degrees C. The structural, morphological, electrical and dielectric properties of the deposited films have been studied. The X-ray diffraction pattern confirmed the polycrystalline nature of the films with a cubic crystal structure. X-ray photoelectron spectroscopy (XPS) showed a good agreement of the thin films stoichiometry with (BaTiO3). A presence of Ba, Ti and O in the BaTiO3 thin films was observed by energy dispersive X-ray analysis. The scanning electron microscopy (SEM) showed the heterogeneous distribution of cubical grains all over the substrate. The grain size decreased with an increase in substrate temperature. The dielectric constant and dielectric loss showed the dispersion behaviour as a function of frequency, measured in the frequency range of 20 Hz to 1 MHz. The AC conductivity (sigma(ac)) measurement showed the linear nature of obtained films, which confirms conduction mechanism due to small polarons. Impedance spectroscopy has been used to study the electrical behaviour of BaTiO3 ferroelectric thin films. The ferroelectric hysteresis loop has been recorded at room temperature.

4

Structural and Electrical Properties of SnO₂:F Thin Films Prepared by Chemical Vapor Deposition Method

100%

Najafi N. , Rozati S.

Acta Physica Polonica A

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2017

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tom 131

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nr 2

222-225

EN

Fluorine doped tin oxide (FTO) thin films were deposited onto glass substrate at different substrate temperatures by a simple and inexpensive method of air pressure chemical vapor deposition. The substrate temperature was kept constant at about 500°C as the optimum temperature, and air was used as both a carrier gas and the oxidizing agent. A very simple method of characterization were carried on to investigate the electrical and structural properties of the prepared thin films. The electrical parameters variations showed that these parameters vary with substrate temperature ranging from an insulator thin film to a highly conductive layer. X-ray diffraction also revealed the structure to be polycrystalline at higher temperatures compared to amorphous structure for lower temperatures.

5

Structural and Optical Properties of Fe2O3 - NiO mixed Thin Films Prepared by Chemical Spray Pyrolysis

100%

Mohmmed N. J. , Habubi M. N.

International Letters of Chemistry, Physics and Astronomy

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2014

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tom Vol. 14, iss. 1

65--85

EN

Mixed Fe2O3 - NiO thin films have been prepared by chemical Spray pyrolysis technique onto glass substrate preheated to 450 °C. The thickness of thin films was found to be (400 ±20) nm. XRD measurements reveal that all the film exhibit polycrystalline hexagonal wrutzite with a preferred orientation along (104) plane for pure and 10 % and 20 % Ni, while for the rest the structure was amorphous. AFM analysis indicate a nanostructure for all the films. The optical energy gap was found to be increased from optical transitions seems to be direct and the optical energy gap seems to be increased from 2.5 to 2.69 eV as the percentage of NiO increase.

6

First-principles study of the elastic and mechanical properties of Ni3Al under high pressure

100%

Boucetta S. , Chihi T. , Ghebouli B. , Fatmi M.

Materials Science Poland

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2010

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tom Vol. 28, No. 1

347--355

EN

A first-principles study of the structural and elastic properties of the intermetallic compound Ni3Al was undertaken, exploiting density-functional theory and generalized gradient approximation (GGA). The elastic constantsC11, C12, and C44 were shown to be sufficiently close to the density of the k-point mesh in the deformed Brillouin zone to conclude that the elastic anisotropy of the coefficient A increases as the pressure increases. Young´s modulus of Ni3Al along {100} is approximately two times higher than that along {111}. The computed elastic constants from first principles satisfy C11 › C12 › C44, which are in good agreement with the experiment data. The cubic Ni3Al possesses a bulk modulus of 312 GPa, comparable to that of cubic hafnium nitride. Theoretical calculations for Ni3Al show that all elastic moduli increase monotonically as the pressure increases. These results suggest there are potential technological applications of such materials in extreme environments.

7

Study of structural and optical properties of TiO2:Tb thin films prepared by high energy reactive magnetron sputtering method

100%

Domaradzki J. , Kaczmarek D. , Prociow E. L. , Wojcieszak D. , Sieradzka K. , Mazur M. , Lapinski M.

Optica Applicata

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2009

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tom Vol. 39, nr 4

815-823

EN

This work is focused on structural and optical properties of TiO2 thin films doped with different amount of terbium. The thin films have been prepared by high energy reactive magnetron sputtering (HE RMS) and by low pressure hot target reactive magnetron sputtering (LP HTRS) processes. Thin films were deposited from mosaic, metallic Ti-Tb target sputtered under oxygen plasma (without argon) at a pressure below 10-1 Pa. Structural examinations show nanocrystalline nature of prepared thin films with either anatase or rutile phases depending on concentration of Tb 0.4 at.% and 2.6 at.%, respectively. The phase transformation from the anatase to the rutile has not been observed after additional post-deposition annealing even at the temperature up to 1000 K. Based on investigations performed with the help of atomic force microscope high nanocrystalline, close-packed structure has been found. Studies of refraction index revealed higher value for the thin films prepared by the HE RMS than by the LP HTRS methods.

8

Effect of Ba addition on the structural, dielectric and ferroelectric properties of Na0.5Bi0.5TiO3 ceramics

100%

Suchanicz J. , Lewczuk R. , Konieczny K. , Dutkiewicz E. M.

Materials Science Poland

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2015

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tom Vol. 33, No. 2

414--417

EN

Lead-free (Na0.5Bi0.5)(1-x)BaxTiO3 (x = 0, 0.04 and 0.06) ceramics were fabricated by conventional solid phase sintering process. X-ray diffraction analysis shows that obtained specimens possess the perovskite structure. The microstructure study shows a dense structure, in good agreement with the relative density determined by the Archimedes method (above 95 %). Electric permittivity anomaly is shifted to low temperature after Ba doping of NBT. The pyroelectric and hysteresis loops measurements show that polarization and coercive field increases and decreases, respectively, after Ba doping of NBT. The obtained results are discussed in terms of ions/lattice imperfections, which create local electromechanical fields. The investigated ceramics are considered to be promising candidates for lead-free electronic materials.

9

A computational approach to structural properties of glycoside hydrolase family 4 from bacteria

100%

Craciun D. , Vlad-Oros B. , Filimon N. , Ostafe V. , Isvoran A.

Acta Biochimica Polonica

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2013

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tom 60

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nr 4

553-564

EN

Structural bioinformatics approaches applied to the alpha- and beta-glycosidases from the GH4 enzyme family reveal that, despite low sequence identity, these enzymes possess quite similar global structural characteristics reflecting a common reaction mechanism. Locally, there are a few distinctive structural characteristics of GH4 alpha- and beta-glycosidases, namely, surface cavities with different geometric characteristics and two regions with highly dissimilar structural organizations and distinct physicochemical properties in the alpha- and beta-glucosidases from Thermotoga maritima. We suggest that these structurally dissimilar regions may be involved in specific protein-protein interactions and this hypothesis is sustained by the predicted distinct functional partners of the investigated proteins. Also, we predict that alpha- and beta-glycosidases from the GH4 enzyme family interact with difenoconazole, a fungicide, but there are different features of these interactions especially concerning the identified structurally distinct regions of the investigated proteins.

10

STRUCTURAL CHARACTERISTICS OF THERMOSENSITIVE CHITOSAN GLUTAMINATE HYDROGELS

100%

Modrzejewska Z. , Nawrotek K. , Zarzycki R. , Douglas T.

Progress on Chemistry and Application of Chitin and its Derivatives

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2013

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tom 18

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nr 18

93-105

EN

Hydrogels that possess the ability of gelling in response to changes in the local environment, such as pH or temperature, have been examined extensively recently. In this paper the properties of thermosensitive chitosan hydrogels prepared with the use of chitosan glutaminate and -glycerophosphate are presented. The sol/gel transition point was determined based on the rheological properties. The structure of gels was observed under the Scanning Electron Microscopy (SEM) and was investigated by thermogravimetric (TG) and differential themogravimetric (DTG) analy¬sis and infrared (IR) spectroscopy. The crystallinity of gel structure was determined by X-ray Diffraction analysis (XRD).

11

Role of pH and current density in electrodeposited soft magnetic Co-Ni-Fe alloy thin films

100%

Sundaram K. , Raja M. , Thanikaikarasan S. , Chu J. P. , Mahalingam T.

Materials Science Poland

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2011

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tom Vol. 29, No. 3

165--170

EN

The influence of pH and current density on the structural and magnetic behavior of soft magnetic Co-Ni-Fe alloy thin films has been studied. The effect of pH and current density on the compositional, structural, and magnetic properties of the as-obtained films was investigated by EDX (energy dispersive analysis by X-rays), XRD (X-ray diffractometer) and VSM (vibrating sample magnetometer). The EDX results revealed that at the optimized deposition conditions, nickel content was low compared with cobalt and ferrous content. X-ray diffraction patterns revealed that the deposited films have polycrystalline nature with mixed (fcc-bcc) cubic structure and small crystallite size (<20 nm). The films prepared in optimized conditions exhibit high saturation magnetization (4pMs value above 2T) and low coercivity (below 160 A/m), which may be due to the reduced crystallite size.

12

Synthesis and characterization of Ag-chalcogenide nanoparticles for possible applications in photovoltaics

100%

Chand S. , Sharma P.

Materials Science Poland

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2018

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tom Vol. 36, No. 3

375--380

EN

Bottom-up technique has been used to synthesize Ag-chalcogenide nanoparticles. This work reports on the synthesis of Ag2Se by varying the molar ratio of capping agent and pH of the solution. The synthesized nanoparticles have been characterized in terms of structural parameters using X-ray diffraction. By this technique, various parameters such as crystallite size, dislocation density and strain of the nanoparticles were calculated. The crystallite size decreased with the increase in pH of the solution. The optical characterization was carried out by UV-Vis-NIR spectrophotometer. With the decrease in the crystallite size, a blue shift in the absorption peak of the nanoparticles was observed. These properties are suitable for energy harvesting with the help of photovoltaics.

13

Influence of substrate type and its placement on structural properties of TiO2 thin films prepared by the high energy reactive magnetron sputtering method

100%

Kaczmarek D. , Prociow E. L. , Domaradzki J. , Borkowska A. , Mielcarek W. , Wojcieszak D.

Materials Science Poland

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2008

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tom Vol. 26, No. 1

113--117

EN

The paper presents studies of the influence of substrate type and its placement on structural properties of TiO2 thin films prepared by the high energy reactive magnetron sputtering method. During the deposition, conditions of the magnetron powering have been especially selected to enhance the nucleation energy. Thin films were deposited on Si(100) and SiO2. Substrates were placed on a plate at three distances from the centre of the target. Selected substrates were also placed under various angles with respect to the plate. Thin films were examined using X-ray diffraction (XRD) and atomic force microscopy (AFM). XRD analysis showed existence of TiO2-rutile phase with preferred (110) orientation and AFM measurements revealed nanocrystalline structure of the films.

14

Structural, morphological, optical and diode properties of chemical bath deposited nano-structured CdS thin films using EDTA as a complexing agent

100%

Vidhya S. N. , Karunakaran R. T.

Materials Science Poland

|

2019

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tom Vol. 37, No. 3

317--323

EN

CdS thin films with (1 1 1) orientation were prepared by chemical bath deposition technique at 80±5 °C using the reaction between NH4OH, CdCl2 and CS(NH2)2. The influence of annealing temperature varying from 150 °C to 250 °C was studied. X-ray diffraction studies revealed that the films are polycrystalline in nature with cubic structure. Various parameters, such as dislocation density, stress and strain, were also evaluated. SEM analysis indicated uniformly distributed nano-structured spherically shaped grains and net like morphology. Optical transmittance study showed the wide transmittance band and absence of absorption in the entire visible region. I-V characterization of p-Si/n-CdS diode and photoluminescence studies were also carried out for the CdS films.

15

Structural, Mechanical and Thermodynamic Properties Under Pressure Effect of Rubidium Telluride: First Principle Calculations

100%

Bidai K. , Ameri M. , Ameri I. , Bensaid D. , Slamani A. , Zaoui A. , Al-Douri Y.

Archives of Metallurgy and Materials

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2017

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tom Vol. 62, iss. 2A

865--871

EN

First-principles density functional theory calculations have been performed to investigate the structural, elastic and thermodynamic properties of rubidium telluride in cubic anti-fluorite (anti-CaF2-type) structure. The calculated ground-state properties of Rb2Te compound such as equilibrium lattice parameter and bulk moduli are investigated by generalized gradient approximation (GGA-PBE) that are based on the optimization of total energy. The elastic constants, Young’s and shear modulus, Poisson ratio, have also been calculated. Our results are in reasonable agreement with the available theoretical and experimental data. The pressure dependence of elastic constant and thermodynamic quantities under high pressure are also calculated and discussed.

16

Structural and dynamic properties of water confined inside a single-walled carbon nanotube - Molecular dynamics study

88%

Kosmider M. , Sokol M. , Dendzik Z. , Gburski Z.

Materials Science Poland

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2005

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tom Vol. 23, No. 2

475--481

EN

Atomically detailed molecular dynamics simulation has been performed to study structural and dynamical properties of the cluster of water molecules (H2O)(80) confined inside an open-ended single-walled (10,10) carbon nanotube (SWNT). The structural and dynamical properties of the confined cluster have been compared with the analogous results for an unconfined cluster of water molecules.

17

Structural and textural characterisation of NiMo catalysts supported on various zeolites

88%

Sarbak Z. , Fabiś G. , Binkowski S.

Polish Journal of Chemical Technology

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2007

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tom 9

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nr 1

27-32

EN

Structural and textural properties of nickel-molybdenum catalysts supported on four various type of zeolites of different chemical composition and porous structure have been studied by the methods of IR, XRD and the low-temperature sorption of nitrogen. The catalysts have been obtained by the two-stage impregnation of the supports with the solutions of nickel and molybdenum salts by the method of incipient wetness. The catalysts have been shown to preserve the structure characteristic of the appropriate zeolite supports.

18

FP-LMTO study of structural, electronic, thermodynamic and optical properties of Mg x Cd1−x Se alloys

88%

Bensaid D. , Ameri M. , El H. M. D. , Azaz Y. , Bendouma D. , Al-Douri Y. , Ameri I.

Materials Science Poland

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2014

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tom Vol. 32, No. 4

719--728

EN

Structural, electronic and optical properties of MgxCd1−xSe (0 6 x 6 1) are calculated for the first time using density functional theory. Our results show that these properties are strongly dependent on molar fraction of particular components – x. The bond between Cd and Se is partially covalent and the covalent nature of the bond decreases as the concentration of Mg increases from 0 % to 100 %. It is found that MgxCd1−xSe has a direct band gap in the entire range of x and the band gap of the alloy increases from 0.43 to 2.46 eV with the increase in Mg concentration. Frequency dependent dielectric constants ε1(ω),ε2(ω) refractive index n(ω) are also calculated and discussed in detail. The peak value of refractive indices shifts to higher energy regions with the increase in Mg. The larger value of the extraordinary refractive index confirms that the material is a positive birefringence crystal. The present comprehensive theoretical study of the optoelectronic properties of the material predicts that it can be effectively used in optoelectronic applications in the wide range of spectra: IR, visible and UV. In addition, we have also predicted the heat capacities (CV ), the entropy (S), the internal energy (U) and the Helmholtz free energy (F) of MgxCd1−xSe ternary alloys.

19

Adsorption behavior of Zn(II) onto natural minerals in wastewater. A comparative study of bentonite and kaolinite

88%

Chai W. , Huang Y. , Su S. , Han G. , Liu J. , Cao Y.

Physicochemical Problems of Mineral Processing

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2017

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tom Vol. 53, iss. 1

264--278

EN

In order to remove the harmful metal ions in lead-zinc mineral processing wastewater, two natural clay minerals (bentonite and kaolin) were used as adsorbents and Zn(II) ions were the emphasis in this work. The adsorption behaviors including kinetics and isotherms were investigated by batch experiments. In addition, the adsorption mechanisms were studied by means of zeta potential testing, optical microscope and XRD analysis. The results show that the adsorption process can be best described as the pseudo-second order kinetic model. The adsorption equilibrium data of bentonite and kaolinite can be respectively fitted best by Langmuir and Freundlich models. Thermodynamic studies display that the adsorption of Zn(II) onto clays is non-spontaneous and endothermic. The maximum capacity of Zn(II) adsorbed on bentonite and kaolinite respectively reaches to 79.2 mg·g-1 and 6.35 mg·g-1 at 25 °C. The structural differences of bentonite and kaolinite result in the differences in adsorption behavior and mechanism. The interaction mechanisms of Zn(II) with bentonite and kaolinite involve electrostatic attraction, cation exchange, surface complex and precipitation. Bentonite as adsorbent has the potential to remove Zn2+ better than kaolinite.

20

Investigations of structural, elastic, electronic and thermodynamic properties of lutetium filled skutterudite LuFe4P12 under pressure effect: FP-LMTO method

88%

Boudia K. , Ameri M. , Al-Douri Y. , Ameri I. , Bouafia H.

Materials Science Poland

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2015

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tom Vol. 33, No. 4

867--878

EN

Structural, elastic, electronic and thermodynamic properties of ternary cubic filled skutterudite compound were calculated. We have computed the elastic modulus and its pressure dependence. From the elastic parameter behavior, it is inferred that this compound is elastically stable and ductile in nature. Through the quasi-harmonic Debye model, in which phononic effects are considered, the effect of pressure P (0 to 50 GPa) and temperature T (0 to 3000 degrees C) on the lattice constant, elastic parameters, bulk modulus B, heat capacity, thermal expansion coefficient alpha, internal energy U, entropy S, Debye temperature theta(D), Helmholtz free energy A, and Gibbs free energy G are investigated.