Titanium oxide (TiO2) thin films have been grown by thermal oxidation of sputtered Titanium (Ti) thin layers using ion beam-assisted deposition (IBAD). X-ray diffraction showed that prior to oxidation, the films are composed of hexagonal crystallites of Ti. After oxidation, a film structure transition occurs from monoclinic beta-TiO2 type to tetragonal anatase type as the annealing temperature of Ti layer is increased from 250 degrees C to 550 degrees C. The film thickness was about 230 nm. Visualization and scanning by atomic force microscope (AFM) revealed a low roughness of the samples, which increases when the annealing temperature is increased. The optical transmittances of the films in the visible spectrum were in the range of 85-95%. The values of optical band gap have been estimated to be 3.43 eV and 3.61 eV, for thin films annealed at 250 degrees C and 550 degrees C, respectively.

Titanium nitride nano-scale thin films have been prepared by ion beam assisted reactive DC magnetron sputtering. The films are characterized by XRD, SEM and TEM. The films are found to be amorphous. The effect of the ion beam during deposition was evident from smoothness of film surface (SEM and TEM images) and modifications in optical properties. Investigation of the optical constants shows stable refractive index dominating most of the visible range. The films are not highly absorptive in the visible range. An energy gap of 2.9±0.1eV is estimated for the IBAD amorphous titanium nitride nano-thin films. The stability of the films at normal room environment in addition to the golden color makes the nano-thin films suitable for hard and decorative coatings.

This paper reports on the synthesis and characterization of Fe-doped ZnO thin films deposited onto gold coated glass substrates, using electrochemical deposition (ECD) technique at room temperature and different concentrations of Fe. X-ray diffraction (XRD), scanning electron microscopy (SEM), photoluminescence (PL) and optical transmission measurements were used to characterize the films. The effect of iron doping on the structural, morphological and optical properties of the films was studied. The XRD spectra of the Fe-ZnO films indicate the polycrystalline nature having hexagonal crystal structure. From the XRD pattern, it is observed that peak positions shift toward lower angles with Fe doping. The change in the peak positions with increase in Fe content clearly indicates that Fe ions replace Zn ions in the ZnO films. The SEM images showed different surface morphologies of the grown structures on the gold layer according to the doping concentration. The shape and dimensions of the structures depend on the doping level. The PL spectra illustrate that there is an obvious red-shift for the emission centre from ultraviolet to blue region. The intensities of emissions from defects increase with the increase of Fe doping. The growth and doping mechanism was also briefly discussed.

Hydrogenated amorphous silicon-carbon thin-films deposited by rf plasma deposition from silane and propane are photo-oxidised by UV illumination at room temperature in air. The process has high spatial resolution and reduces the electrical conductivity of the alloys to the extent that they can be used as gate insulators in field effect transistors.

Five mudrock samples were collected at different stratigraphical positions within the rock column of Jordan. They represent the ages of the late Ordovician-lower Silurian (SIL sample), late Permian (UI sample), Lower Cretaceous (MAH sample), Lower Turonian (TAF sample) and Pleistocene (YAM sample). The results of X-ray diffraction (XRD) analysis of clay fraction (particle size < 2 μm) show that the amount of smectite decreases towards more ancient mudrock samples, i.e. towards an increase of burial depth. Smectite totally disappeared in the Silurian claystone (SIL sample) at a depth of 1.6 km more likely as a function of burial diagenesis. The change of smectite into illite, due to burial history, was through a mixed layer illite-smectite intermediate stage of alteration. The shape of crystallite thickness distributions (CTDs) for illite was asymptotic in all study samples. This means that the crystal growth mechanism of illite particles was similar regardless of the burial depth of sediments and was concurrent with nucleation. The XRD patterns showed that the degree of Kaolinite crystallinity increased generally with depth as the 001 reflection becomes sharper and narrower. The CTDs shapes for kaolinite were somewhat different. It was asymptotic in YAM and TAF samples, multimodal in MAH sample, and lognormal in UI and SIL samples. These variations in CTDs distributions reflect the fact that crystal growth mechanism of kaolinite differed with burial depth. Kaolinite crystal growth accompanied with nucleation was only at shallow-moderate depths. This changed to crystal growth without continued nucleation at greater depths.

A novel implementation of simultaneous use of ion beam assisted deposition (IBAD) and reactive dc magnetron sputtering of a metal copper target in pure nitrogen plasma to produce thin films of amorphous copper nitride (a-CuxN) is described. This technique produced amorphous thin films, very stable and optically comparable with crystalline copper nitride (Cu3N) films produced by several deposition methods. The work also reports on the optical characteristics and determination of the optical constants of this material following a recently introduced method of calculations, PUMA. The optical energy gap 2.03 ± 0.0342 eV deduced from the transmittances measurements is slightly higher than that reported for the Cu3N films over a range of 1.2–1.9 eV.

α–Fe2O3/TiO2 Composite powders have been prepared by high energy ball-milling for different times. The composites were studied using Mössbauer Spectroscopy (MS) and X-ray diffraction (XRD). The patterns of XRD show broadening in the diffraction peaks, indicating a decrease in the particle size of the composites with milling time. Also, the XRD patterns show an evolving new structural phase correlated with an evolving Titanium ferrite species with milling time. Mössbauer Spectroscopy shows the evolving titanium ferrite species characterized by a quadrupole doublet at the expense of the α–Fe2O3 represented by the magnetic sextet. The doublet corresponding to the Ti-ferrite phase dominates the Mössbauer spectra at long milling time (greater than 100 h of milling).

Preparation and characterization of NiBi nano- and micro-particles are presented. Firstly, predetermined compositions were obtained by simultaneous precipitation from solutions of Bi(NO(3))(3) and Ni(NO(3))(2). The precipitates were heated under oxygen flow and in air, and thereafter reduced to metals under hydrogen flow at 673 K. Correlation between the predetermined and the actual compositions of the products was found. Characterization of the precipitates was carried out employing X-ray diffraction, scanning and transmission electron microscopy. Nickel-bismuth intermetallic phase (NiBi) particles with nano- and micro-dimensions were observed in the samples after reduction. The other possible Ni-Bi intermediate phase (NiBi(3)) did not form at these conditions although its presence was expected according to the phase diagram. This finding might be useful for the implementation of Bi-based solders where the growth of the compound NiBi(3) in the solder joints must be prevented. (C) 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Abstract An attempt at the preparation and characterization of Co – Bi nano- and micro-particles is presented. Firstly, predetermined compositions were obtained by simultaneous precipitation from solutions containing Bi(NO3)3 · 5 H2O and Co(NO3)3 · × H2O. The precipitates were heated under oxygen flow and in air, and thereafter reduced to metals under hydrogen flow at 673 K. Correlation between the predetermined and the actual compositions of the products was found. Characterization of the precipitates was carried out employing X-ray diffraction, scanning and transmission electron microscopy. The dimensions of the particles vary from nano- to micro- scale sizes. It was found that face centered cubic cobalt (i. e. fcc-Co modification, that is metastable up to 695 K) is the predominant cobalt phase while the hexagonal close packed cobalt (hcp-Co) is only present in small amounts. Thermodynamic calculations have shown that the molar specific surface energy of the fcc-Co should be around 0.5 J m−2 less than that of the hcp-Co (3.2 J m−2), in order to make the small fcc-Co particles more stable than those of hcp-Co.

The crystal structure of an Alnico-5 Alloy during different annealing temperature up to 1050 °C for 1 hour has been monitored by measuring the magnetic hysteresis loop. X-ray diffraction and vibrating sample magnetometer (VSM) were used to characterize the phase composition and magnetic properties. The results found that, the effect of the annealing degree is the major parameter on particle size, phase transition and magnetic properties. The results also showed that grain size decreased with the increasing temperature from 18.3 nm at room temperature to 12.2 nm at 950°C. The maximum coercive force (He) with residual magnetization (Br) also increased with increasing temperatures above RT. The oxidation of the alloy with new crystalline phase leads to change the magnetic and structure properties at 1050 °C were found. A good correlation has been established between the structure and magnetic properties.

The effects of the presence of a uniform magnetic field on the growth rate and the threshold intensity of the two-plasmon decay in a homogeneous plasma have been investigated. Analytical expressions for the growth rate and threshold intensity have been obtained. It has been shown that the presence of a magnetic field affects significantly the growth rate and the threshold intensity for the two-plasmon decay.

A study is made of the two-plasmon decay when the pump laser beam has a finite bandwidth. Using the fluid theory, analytical expressions for the growth rates and threshold powers for homogeneous plasma and inhomogeneous plasma with linear ramp density were obtained; it has been shown that the bandwidth in the laser beam can significantly affect the growth rates and threshold powers for the two-plasmon decay process.

The effect of bandwidth on Raman backscattering is investigated and an expression for convective amplification is derived, where the effects of collision and phase mismatch were taken into consideration. We found that if we neglect the collision frequency, the dependence of the amplification factor on the bandwidth disappears. The growth rate was also investigated and it was found to decrease with bandwidth. We obtained a formula to estimate the threshold intensity of the pump wave.

Using a statistical mechanical method we have calculated the magnetization and the initial susceptibility for a ferrofluid composed of fine, uniform spherical particles, taking into account the magnetic dipole interactions in the dimer model under a reasonable condition. We have found that the initial susceptibility is consistent with a Curie law rather than a Curie-Weiss law. That means, for low fields and relatively high temperatures, the system of N particles, in the dimer model, behaves as a superparamagnetic gas of N /2 pairs.

The authors present the effect of intergrain interactions, at T=75 K, on the intragranular critical current density and on the susceptibility of a system consisting of small superconducting grains of GdBa2Cu3O7- delta embedded in solid epoxy. The critical current density in a single grain is unaffected by the intergrain interactions. They also found that the magnetic screening volume susceptibility, chi , varies linearly with the grain concentration epsilon , of the system. Non-interacting models can be used to describe the magnetic phenomena of such systems. Finally the variation of - chi with epsilon was found to be strong near the first critical field HCl and - chi becomes insensitive to epsilon in the neighbourhood of H0, which the authors call the cut-off field.

The isochronal thermal decomposition of polysilane, -(SiH2) n- , has been investigated at temperatures up to 335°C by in situ infrared spectroscopy. The studies were performed, in vacuo, on compressed discs of polysilane in a KBr matrix. Dehydrogenation was measured by the reduction of the infrared stretching ωs(2100 cm−1), bending ωb(910 cm−1), wagging ωw(865 cm−1) and rocking ωr(650 cm−1) integrated band intensities. The wavenumbers of the infrared-active modes of -(SiH2) n - given in parenthesis correspond to room temperature samples. Loss of hydrogen occurs at relatively low temperatures, ca. 140–200°C, and is essentially complete at 335°C. The integrated intensities of each band show an equal decrease with time. However, the peak position of the essentially degenerate symmetric and asymmetric stretching mode shifted systematically to lower wave-numbers in the region 2100 cm−1-2080 cm−1 on dehydrogenation. No shift was effected in the doublet of peaks in the range 800–950 cm−1 under the same conditions. The width (f.w.h.m.) of the 650 cm−1 band decreased with a reduction in the hydrogen content. This band exhibited a slight red shift of 10 cm−1 on dehydrogenation. Preliminary studies of the oxidized polysilane films demonstrated that rearrangement of [SiH2O] groupings to [SiH2O2] groupings takes place at elevated temperatures.

The d.c. electrical conductivity of polysilane, (SiH2)x, as compressed discs, has been measured at 298 K; values of the conductivity lie in the range 10–7–10–11Ω–1 cm–1 for pristine samples of polysilane.