Gabriel O. Egharevba

Preparation and characterization of pyrolytically deposited (Co–V–O and Cr–V–O) thin films

The metal acetylacetonates of vanadium, cobalt and chromium were prepared from commercial reagents. The corresponding metal acetylacetonates were mixed in desired ratio and deposited on soda lime glass substrate by metal organic chemical vapor deposition technique. Mixed oxides thin films with atomic composition Co VO and Cr V O were obtained. A combination 0.31 1.37 5 0.5 2 5 of Rutherford backscattering spectroscopy and energy-dispersive X-ray fluorescence was used for the transition element identification and atomic compositional study of the thin films. The thickness of the Co – V– O and Cr – V– O thin films was 166 and 127 nm, respectively. The optical spectra of the films were obtained using a Pye Unicam SP8-400 spectrophotometer in the ultraviolet yvisible region. The result of the spectral analyses gave the optical bandgap energy of the materials. The temperature dependence of the electrical resistivity measured using the Van der Pauw method indicated that the materials are semiconducting. Their activation energy was obtained from plots of the natural logarithm of conductivity vs. the reciprocal of temperature. The sign of the thermopower shows that both materials are p-type semiconductors. � 2002 Elsevier Science B.V. All rights reserved.

Synthesis and Some Properties of Metal Organic Chemical Vapour Deposited Molybdenum Oxysulphide Thin Films

of oxygen. The large amount of oxygen was attributed to the large abundance of oxygen in the starting material. A direct optical energy gap of 3.31 eV was obtained from the analysis of the absorption spectrum. The scanning electron microscopy (SEM) micrographs of the fllms showed that the fllms were continuous and porous. An estimated average size of the grains was below 5 „m. X-ray difiraction (XRD) showed that the deposited fllms were crystalline in nature.

Preparation and characterization of undoped zinc oxide and uranium doped zinc oxide thin films

Doped and undoped zinc oxide thin films were deposited by metallorganic chemical vapour deposition technique, which has been reported previously. The undoped zinc oxide thin films were deposited from the pyrolysis of zinc acetate while those of uranium-doped zinc oxide were deposited from uranyl zinc acetate. The scanning electron microscope micrograph shows that the ZnO thin film has polycrystalline structure. The band gaps of the undoped ZnO and uranium doped ZnO thin films were determined using optical technique and found to be 3.24 and 3.16 eV respectively.

Preparation and characterization of metallorganic chemical vapour deposited LixMoyOz using a single source solid precursor

Thin films of LixMoyOz have been deposited on glass substrate in a one step chemical vapour deposition using a single source solid precursor. The films were characterized using Rutherford Backscattering Spectroscopy (RBS), X-Ray Diffractometry, Scanning Electron Microscopy (SEM), Impedance Spectroscopy (IS), van der Pauw conductivity measurement and Ultraviolet-Visible Spectroscopy. Results of the characterization showed that the films are dendritic, polycrystalline and semiconducting with an optical transition energy of 3.0 eV. IS characterization gave a semicircle in the complex impedance plot. The conductivity vs. temperature plot showed a transition at 450 °C and also a hysteresis. Analysis showed the film to be mixture of phases.

1-Benzyl-3-[(4-methyl­phen­yl)imino]­indolin-2-one

In the title compound, C22H18N2O, the phenyl and tolyl rings make dihedral angles of 84.71 (7) and 65.11 (6)°, respectively, with the isatin group. The aromatic rings make a dihedral angle of 60.90 (8)°. The imino C=N double bond, exists in an E conformation. In the crystal, molecules are linked by weak π–π stacking interactions [centroid–centroid distance = 3.6598 (13) Å].

Crystal structure of tricarbon­yltris(pyri­dine-κN)rhenium(I) tetra­fluorido­borate

In the title compound, [Re(C6H5N)3(CO)3]BF4, the ReI ion is six-coordinated by three pyridine N atoms and three carbonyl C atoms. In each case, the carbonyl C atom lies trans to a pyridine N atom. In the crystal, the ions are linked via C—H⋯F hydrogen bonds and C—H⋯π interactions, forming a three-dimensional framework. The F atoms of the BF4 anion are disordered over two positions and gave a final refined occupancy ratio of 0.705 (11):0.295 (11).

Novel adducts of ethanedialdioxime with halides of nickel(II) and cobalt(II)

SummaryEthanedialdioxime (glyoxime, gH2) readily combines with dry CoCl2, NiCl2, and NiBr2 in non-aqueous medium to yield the novel adducts CoCl2(gH2), NiCl2(gH2), and NiBr2(gH2). Synthesis, conventional characterization and magnetic moment data collected in the temperature range 95–293 K are reported for these diamagnetic adducts.