47 research outputs found
Some Thermoelectrical Properties of Thiospinels Cu2B II Ti3 S 8 (B II –Cr, Mn, Fe, Co, Ni)
У роботі досліджено окремі електричні та термоелектричні властивості маловивчених складних шпінелей
Cu2B
II
Ti3
S
8 (B
II
–Cr, Mn, Fe, Co, Ni). Встановлено особливості їх електропровідностей і значення коефіцієнта
об’ємної термо-е.р.с. Згідно знаку термо-е.р.с., всі сполуки належать до напівпровідників n-типу провідності. ; Some electrical and thermoelectrical properties of poorly investigated complex
thiospinels Cu2B
II
Ti3
S
8 (B
II
–Cr, Mn, Fe, Co, Ni), such as peculiarities of their electroconductivity at 295 K, thermoE.M.P. factor, were determined. The sign of termo-E.M.P. indicates, that all compounds belong to the n-type
semiconductors
Optical and structural studies of phase transformations and composition fluctuations at annealing of Zn₁₋xCdxO films grown by dc magnetron sputtering
Ternary Zn₁₋xCdxO (x < 0.12) alloy crystalline films with highly preferred
orientation (002) have been successfully deposited on sapphire c-Al₂O₃ substrates using
the direct current (dc) reactive magnetron sputtering technique and annealed at
temperature 600 °C in air. The structural and optical properties of Zn₁₋xCdxO thin films
were systematically studied using X-ray photoelectron spectroscopy (XPS), X-ray
diffraction (XRD), micro-Raman and photoluminescent (PL) spectroscopy. XPS
measurements clearly confirmed Cd incorporation into ZnO lattice. XRD data revealed
that the growth of wurtzite Zn₁₋xCdxO films occurs preferentially in the (002) direction.
Also, when the Cd content is increased, the XRD peaks shift towards smaller angles and
the full width at half-maximum of the lines increases. When the Cd content increases,
LO A1 ( Zn₁₋CdxO )-like Raman modes show composition dependent frequency decrease
and asymmetrical broadening. The near band-edge PL emission at room temperature
shifts gradually to lower energies as the Cd content increases and reaches 2.68 eV for the
highest Cd content (x = 0.12). The analysis of NBE band emission and Raman LO A1 ( Zn₁₋xCdxO ) mode shows that at a higher Cd content the coexistence of
Zn₁₋xCdxO areas with different concentrations of Cd inside the same film occurs. The
presence of CdO in annealed Zn₁₋xCdxO films with the higher Cd content was
confirmed by Raman spectra of cubic CdO nanoinclusions. The XRD data also revealed
phase segregation of cubic CdO in annealed Zn₁₋xCdxO films (Tann = 600 °C) for
x ≥ 0.013
Controlled Growth of WO3Nanostructures with Three Different Morphologies and Their Structural, Optical, and Photodecomposition Studies
Tungsten trioxide (WO3) nanostructures were synthesized by hydrothermal method using sodium tungstate (Na2WO4·2H2O) alone as starting material, and sodium tungstate in presence of ferrous ammonium sulfate [(NH4)2Fe(SO4)2·6H2O] or cobalt chloride (CoCl2·6H2O) as structure-directing agents. Orthorhombic WO3having a rectangular slab-like morphology was obtained when Na2WO4·2H2O was used alone. When ferrous ammonium sulfate and cobalt chloride were added to sodium tungstate, hexagonal WO3nanowire clusters and hexagonal WO3nanorods were obtained, respectively. The crystal structure and orientation of the synthesized products were studied by X-ray diffraction (XRD), micro-Raman spectroscopy, and high-resolution transmission electron microscopy (HRTEM), and their chemical composition was analyzed by X-ray photoelectron spectroscopy (XPS). The optical properties of the synthesized products were verified by UV–Vis and photoluminescence studies. A photodegradation study on Procion Red MX 5B was also carried out, showing that the hexagonal WO3nanowire clusters had the highest photodegradation efficiency
Active removal of waste dye pollutants using Ta[sub]3N[sub]5/W[sub]18O[sub]49 nanocomposite fibres
A scalable solvothermal technique is reported for the synthesis of a photocatalytic composite material consisting of orthorhombic Ta3N5 nanoparticles and WOx≤3 nanowires. Through X-ray diffraction and X-ray photoelectron spectroscopy, the as-grown tungsten(VI) sub-oxide was identified as monoclinic W18O49. The composite material catalysed the degradation of Rhodamine B at over double the rate of the Ta3N5 nanoparticles alone under illumination by white light, and continued to exhibit superior catalytic properties following recycling of the catalysts. Moreover, strong molecular adsorption of the dye to the W18O49 component of the composite resulted in near-complete decolourisation of the solution prior to light exposure. The radical species involved within the photocatalytic mechanisms were also explored through use of scavenger reagents. Our research demonstrates the exciting potential of this novel photocatalyst for the degradation of organic contaminants, and to the authors’ knowledge the material has not been investigated previously. In addition, the simplicity of the synthesis process indicates that the material is a viable candidate for the scale-up and removal of dye pollutants on a wider scale
XPS and Raman Characterizations of Films Grown at the Different Growth Conditions
X-ray photoelectron spectroscopy was employed to characterize the surface chemistry and electronic properties of the semiconductor systems obtained at the different growth conditions. The effect of the growth conditions on the core and valence band spectra as well as room-temperature photoluminescence of the films was investigated and discussed. Behavior of the X-ray photoelectron spectroscopy peaks indicated an increase of the cadmium and a depletion of the oxygen concentrations upon changing the Ar/ gas ratio and dc power
X-Ray Photoelectron Spectroscopy Study of Nitrogen and Aluminum-Nitrogen Doped ZnO Films
Undoped, nitrogen-doped and aluminum-nitrogen co-doped ZnO films were deposited on Si substrates by magnetron sputtering using layer-by-layer method of growth. X-ray photoelectron spectroscopy was employed to characterize electronic properties of undoped and nitrogen doped ZnO films. The effects of N and N-Al incorporation into the ZnO matrix on the X-ray photoelectron spectroscopy core-level and valence-band spectra of the films were studied and discussed