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 Zn1−xCdxOZn_{1-x}Cd_{x}O Films Grown at the Different Growth Conditions

X-ray photoelectron spectroscopy was employed to characterize the surface chemistry and electronic properties of the $Zn_{1-x}Cd_{x}O$ 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 $Zn_{1-x}Cd_{x}O$ 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/$O_2$ gas ratio and dc power

Raman Submicron Spatial Mapping of Individual Mn-doped ZnO Nanorods

ZnO nanorods (NRs) arrays doped with a large concentration of Mn synthesized by aqueous chemical growth and were characterized by SEM, photoluminescence, Raman scattering, magnetic force microscopy (MFM). By comparison of spectra taken on pure and Mn-doped ZnO NRs, a few new Raman impurity-related phonon modes, resulting from the presence of Mn in the investigated samples. We also present a vibrational and magnetic characterization of individual lying nanorods using Raman and MFM imaging. Confocal scanning micro-Raman mapping of the spatial distribution of intensity and frequency of phonon modes in single Mn-doped ZnO NRs nanorods is presented and analyzed for the first time. Mn-related local vibrational modes are also registered in Raman spectra of the single nanorod, confirming the incorporation of Mn into the ZnO host matrix. At higher Mn concentration the structural transformation toward the spinel phase ZnMn2O4 and Mn3O4 is observed mainly in 2D bottom layers. MFM images of Mn-doped ZnO NR arrays and single nanorod were studied in nanoscale at room temperature and demonstrate magnetic behavior. The circular domain magnetic pattern on top of single nanorod originated to superposition of some separate domains inside rod. This demonstrates that long-range ferromagnetic order is present at room temperature. Aligned Mn-doped ZnO NRs demonstrates that long-range ferromagnetic order and may be applied to future spintronic applications.Funding Agencies|NATO SfP Grant [984735]</p