Engineering and Technology Journal

TiO2 nanocrystalline thin films are widely used as antireflection coating
in solar cell, in this paper, RF magnetron sputtering technique is used to prepare
TiO2 thin film on glass substrates, TiO2 thin films deposited under different
powers (75,100,125 and 150) Watt for (1.5) hour resulted in different layer
thickness (62.5,88,118 and 132.6) nm respectively. The optical properties
examined by UV-VIS spectroscopy. TiO2 thin films exhibit a high transparency in
the region from about 350 nm above, we suggest that these results indicate the
most suitable growing conditions for obtaining high quality sputtered TiO2 thin
films with higher transparence performance for solar cell application. the optical
absorbance coefficient for all films were genuinely high esteems coming to above
104 cm-1, which implies that there is allowed direct transitions, the energy gab
reach to the typical value of the bulk TiO2 (3.5) eV.

Synthesis of titanium dioxide (TiO2) Thin film on three microscope glasses using sol-gel method has been studied intensively. The starting materials were titanium(III)chloride, Ammonium Hydroxide. The components were mixed together to form the sol. Then, at 50℃ heating and ageing was applied to form stable sol-gel . Every glass substrate dipping in sol-gel beaker for period time (1,3,5)min respectively, for obtaining different thickness films. To evaluate the performance of films, After annealing at 500℃ , the crystallinity of the films was determined by using the x-ray diffractometer (XRD). The change on the surface morphology was observed using Atomic Force Microscope(AFM). Finally, Optical properties measurements Absorbance (A) and transmittance(T)) for (TiO2) films were studied by UV-Visible spectrometer.
analysis on the films. It has been successfully shown that the anatase crystalline phase was observed when the TiO2 thin film was annealing at 500°C. The roughness and the crystalline size of TiO2 thin film changed with the thickness. The minimum grain size( 6.92) nm for thickness 1.2µm UV-visible studying that absorption is maximum at UV spectrum (opaque) and the transmittance is maximum at the visible spectrum

TiO2 thin films have been deposited at room temperature with different concentration of CdO of x= (0.0, 0.05, 0.1, 0.15and 0.2) wt. % onto glass substrates by pulsed laser deposition (PLD) technique using Nd-YAG laser with λ=1064nm, energy=800mJ and number of shots=500. The structural, morphological and optical characterizations of as- deposited films were carried out using X-ray diffraction (XRD), atomic force microscopy (AFM), and UV–vis transmittance spectroscopy. The Effect of CdO content on these properties was investigated. Characterizations by X-ray diffraction show a polycrystalline film, with tetragonal structure and formation of Rutile phase and many peaks (110), (101), (111) and (211) were appear. In addition, AFM investigation shows no cracks in the formed layer. The optical properties concerning the absorption and transmission spectra were studied for the prepared thin films using an ultraviolet–visible near-infrared spectrophotometer. The results show that the transmittance of the TiO2 film in the visible domain reaches 75%.Optical band gaps were calculated and found to be (3.62, 3.54, 3.45, 3.3 and 3.21) eV for the concentration of CdO x= (0.0, 0.05, 0.1, 0.15 and 0.2) wt. % respectively. At 350 nm the refractive index,extinction coefficient and dielectric constant were determined.

Transparent conducting oxides thin films of copper aluminium oxide (CuA1O2) were prepared from mixture of CuCl2 and Al2Cl3 salts by spray pyrolysis technique on a glass substrate at temperature (500oC). The as-deposited film show pure delaffosite phase of CuAlO2 by XRD spectra, also many peaks of CuAlO2 were appeared after annealing at different energy fluence. The optical transmission of thin films was measured by UV-VIS spectrometer and reach to 74% in visible region. The direct and indirect optical band gaps of the films are found in the range of (3.4-3.1) eV, and (2.1-1.5) eV, respectively depending on the annealing energy fluence at (300, 600, 900, 1200) mJ/cm2.

This work involves study corrosion behavior of amalgam in presence of some vegetables including (Carrots, Onion, Parsley, and Red radish) which were chosen because they require mastication process by teeth and taking enough time that make them in a contact with amalgams filling in artificial saliva.
The corrosion parameters were interpreted in artificial saliva at pH (5.1) and (37±1oC) by adding (50 ml/l) of vegetable juice to artificial saliva, which involve corrosion potential (Ecorr), corrosion current density (icorr), Cathodic and anodic Tafel slopes (bc & ba ) and polarization resistance, the results of (Ecorr) and (icorr) indicate that the medium of saliva and (50 ml/l) onion is more corrosive than the other media. Cathodic and anodic tafel slopes were used to calculate the polarization resistance (Rp) to know which medium more effective on amalgam of dental filling, this study shows that the increasing in polarization resistance through the decreasing in corrosion rate values, the results of (Rp) take the sequence:
Rp:( saliva+ parsley) >( saliva+ red radish)> saliva>(saliva+ carrots) >(saliva+ onion).
While corrosion rates (CR ) take the sequence:
CR: (Saliva+Parsley) Keywords

Amalgam
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Corrosion in saliva
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Potentiostatic measurements

Titanium doxide (TiO2) thin films were deposited on quartz substrates by spray pyrolysis method using titanium tetrachloride as precursor solution. Thin films were deposited at temperature substrate 350 ◦C and annealed at 550 ◦C in air for 120 min. Polycrystalline thin films with anatas crystal structure, as evidenced from X-ray diffraction pattern. Optical study shows the optical band gap has been increased with increasing of dopant. Electrical properties have been studied by means of electrical resistivity and Hall measurement. The sensitivity of TiO2: 5% Cr to NH3 gas with concentration 5ppm at room temperature has been modified to (93) % as compared with a pure TiO2.

The present work was concerned with study of the methyl orange(MO) dye concentration effect on the optical properties ,and electrical properties of polystyrene(PS).
The samples were casted as films from the homopolymer(PS) stated above and the Dye/PS(MO/PS)composites at (3.44,6.7,and 12.5%) concentration. These prepared polymer systems were evaluated spectrophotometically. It was found increasing in absorption spectra with increasing of the dye concentration in Dye/PS composites above, which was attributed to the increasing in localized states. The results proved that the best absorption was of (12.5%MO/PS), and of the lowest energy gap was (3.15eV),The optical constant (α,k,n, εr, and εi)for the homopolymer (PS) , (Dye/PS) composites, and hybrid composites at different concentration were investigated at(λc,300nm). It was seen that there was nonlinear relationship between the optical constants and the concentration ratio, which was attributed to their incompatibility. These results were confirmed with optical micrographs. The (FTIR) spectra showed shifting, appearance ,and disappearance of new band, which was attributed to change in tacticity, geometry in the structure ,and overlapping of polymer composites band involved. The results proved that there was nonlinear relationship between the carrier concentration, mobility, fast increase in the (12.5%MO/PS, and became of order(10-6). The increase in the conductivity with dye concentration was attributed to increase of the localized states in the energy gap.

The optical reflection, transmission, and UV/VIS- absorption spectra had been recorded in the wavelength(200-500nm) for PM-355 before and after irradiation with γ-ray irradiation by using 60Co-dose within range of(30-160Mrad) at normal conditions. The absorption spectra of irradiated samples showed radiation induced absorption changes by photodegradation. There was an increment in absorption proportional with irradiation dose. The optical constants (α,Kex,n,εi,εr,Eg,) were calculated for all samples. The effect of irradiation on the optical constants of the PM-355 before and after irradiation had been investigated.

In the present Work, effect of substrate temperatures on the optical and morphological properties of In2O3 trioxide thin film has been carried out using Reactive Pulsed Laser as a Deposition technique (RPLD). 1.064µm, 7 nsec Q-switch Nd-YAG laser with 400 mJ/cm2 laser energy’s has been used to ablated pure Indium target and deposited on glass substrates . The resulted films show High transparency reached to about (85) % which found to decrease sharply with the substrate temperatures. The estimated optical band gap found to be about 3.6eV at optimum substrate temperatures (70 Co). The FTIR results insure the formation ofIn-O vibrational bond with different vibrational intensity depending on substrate temperatures.

This work includes the deposition of WO3 as a thin film on glass substrates by pulsed laser deposition method. The influence of Oxygen pressure on the structural and optical properties of tungsten trioxide films was investigated. The X-ray diffraction results show that the structure of the films changes from amorphous to crystalline at an Oxygen pressure higher than 10-2 mbar. The color of WO3 films formed at Oxygen pressure of 10-2 mbar is translucent white and it changes to pale blue with increasing the Oxygen pressure. From UV-visible spectroscopy the distinct variations in the transmission spectra and optical energy gap of the thin films were also observed. The optical band gap of the prepared films determined at different Oxygen pressures and it is found to be 3-3.1-3.12 eV at Oxygen pressures of 10-2 -2×10-1 -5×10-1 mbar respectively.

In this work, silver nanoparticles has been prepared via ablation of pure Ag metal target in distilled water was accomplished using Q-switched Nd:YAG laser at (1.06 µm) laser wavelength , with different laser energy and number of laser pulses. The effect of these parameters on the optical and surface morphology have been studied , UV-Visible show a red shift in the absorption spectra related to the shift in the energy gap due to increment of the grain of prepared particles size is increased as laser energy. Grain size of the obtained NPs are found to increase with laser energy with rang (20-112) nm as shown by the SEM result.

In this work, mixed oxide (TiO2-SnO2) thin films were grown on Si (111) and glass substrates by pulsed laser deposition (PLD) method. The influences of increasing amounts of SnO2 were investigated. The X-ray diffraction results show the peaks position of the plane was shifted towards higher angle values with increasing amounts of SnO2. The surface morphology of the deposits materials was also studied by using a scanning electron microscope(SEM) The results show that, the grain sizes decreases with increasing SnO2 content from the largest value (53.6)nm to smallest value (25.5) nm. From UV-visible spectroscopy, the distinct variations in the transmission spectra, and optical energy gap, of the thin films were also observed.

In this work, CuO thin films were prepared by spray pyrolysis method using different concentration of CuCl2 .2H2O. X- ray diffraction (XRD) and UV-VIS transmission spectroscopy were employed to characterize the structure and optical properties of prepared films.XRD patterns show that the films are polycrystalline and monoclinic with (-111) and (111) crystalline orientations. The optical band gaps (2.05 to2.42eV) ,with high absorption coefficient change from (3*105 - 1*105) cm-1 at 0.3M concentration , and excitation coefficient change from (0.85 – 0.7). These constants are found to be oscillatory in nature, which are attributed to the particular structure of films and their concentration.

Indium Selenide films were deposited by pulsed laser deposition (PLD) with a Nd-YAG laser under vacuum condition. During the deposition, the substrates were kept at room temperature. The typical thicknesses of films were 200nm, 800 nm. The films were analyzed by X-ray diffraction for the crystallographic, the surface morphology of the film were investigated by AFM. It has been observed that grain growth depend on film thickness. The optical properties were characterized in the ultraviolet–visible region employing optical transmission, absorption, band gap. The direct optical band gap value for the films was found to be of the order of (2.2, 2.1) eV for thickness (200,800) nm respectively at room temperature.

In this work, Nanostructured TiO2 thin films were grown by pulsed laser deposition (PLD) technique on glass substrates at 300 °C. TiO2 thin films were then annealed at 400-600 °C in air for a period of 2 hours. Effect of annealing on the structure, morphology and optical properties were studied. The X-ray diffraction (XRD) and Atomic Force Microscopy (AFM) measurements confirmed that the films grown by this technique have good crystalline tetragonal mixed anatase and rutile phase structure and homogeneous surface. The study also reveals that the RMS value of thin films roughness increased with increasing annealing temperature .The optical properties of the films were studied by UV-VIS spectrophotometer. The optical transmission results shows that the transmission over than ~65% which decrease with the increasing of annealing temperatures. The allowed indirect optical band gap of the films was estimated to be in the range from 3.49 to 3.1 eV. The allowed direct band gap was found to decrease from 3.74 to 3.55 eV with the increase of annealing temperature. The refractive index of the films was found from 2.27 -2.98 at 550nm. The extinction coefficient increase with annealing temperature.

Nanocrystalline PbS thin films have been deposited on glass substrates by Chemical Bath Deposition (CBD) technique using lead acetate ,KoH, thiourea and T.E.A. The films were btained in a reaction bath at times of (15 ,30 ,45 ,60 and 90)min. Structure and surface morphology of thin films were characterized by X-ray diffraction and scanning electron microscopy (SEM). XRD indicates that the films have cubic structure. The crystallite size of the films were found to vary from (4.9 to 11.3 nm).The band gaps of the nanocrystalline PbS were determined from UV-Vis spectrophotometer and were found to be in the range( 1.72 -2.4 eV).

Cadmium oxide thin film has been synthesized using spray pyrolysis method. The structural and optical properties of the film were study by usingX-ray diffraction (XRD), scanning electron microscopy (SEM), Atomic Force microscope (AFM), and UV- VIS spectroscopy. Result show that the film has spherical shape grain with size (460nm) and band gap (2.49eV). Moreover, the RMS equal to 58.7 nm.

In this work porous silicon where prepared by chemical etching assisted with laser. The structural and optical properties of porous silicon are investigated using atomic force microscopy (AFM) and FTIR spectroscope. FTIR spectrum exhibit the formation of SiHx (x=1,2) and Si-O bonds. The atomic force microscopy AFM investigation shows the surface roughness (RMS observed was 1.52nm with laser and 1. 86 nm without laser ) and pyramid like hillocks surface on entire surface which can be regarded as a condensation point to form small skeleton clusters which plays an important role for the strong visible luminescence.

In the present work, preparation of transparent conductive SnO2 thin films by
classical-oxidation technique of thermal evaporated tin metal films, on glass substrates
was carried out. The optical properties showed high transmission at visible and NIR
regions. The energy band gap was found to be (3.82eV). The structure properties
showed that the tin oxide peak appears at (2q =30.24) and (2ϴ=63.39°) . The atomic
force microscopy (AFM) results showed a nano-structured for the thin film with
particle size ranging (15-140)nm and its root mean square (RMS) value was found to
be (5.72 nm ).

The aim of the present work is concerned with the study of the optical
constants of the PMMA/PC blend at different concentrations.
The samples are casted as films from the PMMA and PC homopolymers and
blend. These polymer systems are evaluated spectrophotometically. The
absorption spectra of homopolymers and PMMA/PC blends at different
concertation showed absorption changes in the wavelength range, which depends
on the polymer type, and the concentration of the polymer blends. It was found
that 50% ratio from these polymers showed higher absorption values in
comparison with the homopolymers, besides, the absorption spectroscopy of the
polymer blends did not always effect the similar information obtained from the
spectroscopy of the homopolymers .A phenomenon was attributed to immiscibility
or phase separation as associated with the blends formation. The results of the
optical constant proved that 50%ratio was the best, which was attributed to the
lowest energy gap (2.5 eV). Morphological investigations for the
casted polymer systems were introduced.

The samples were cast as thin film from homopolymer (PMMA) before
and after doping with methyl orange at different concentration. The samples were
exposed to UV-radiation for exposure time within (10-50hr) range. These polymer
systems were evaluated spectrophotometrically for using the UV-detector. The
absorption spectra of UV-irradiated samples showed radiation induced absorption
changes in the wavelength range, which depends on the polymer type and polymer
composites. The increment depends dopant concentration, especially in ultra violet
region in exposed PMMA doped with methyl orange at 6.7×10-2wt/wt
concentration. Decreasing in absorption was found for the cases in which, photo
degradation caused surface damage, i.e. crazes or cracks formation, especially at
ultraviolet region. Calibration curves were drawn at peaks, selected wavelength in
the absorption spectra. The linear regions from the calibration curves were selected,
and dosimeter range was determined from the UV-irradiation sample response. It
was found that PMMA doped with methyl orange at 6.7×10 -2wt/wt concentration
can be use the UV-detector within range (10-40hr) at the wavelength of (300nm)
for its linear response at this range of irradiation.
Morphological investigations for the surface damages caused by thermal and photo
degradation are detected by optical microscope. It is found that the photo
degradation could easily lead to some mechanical surface degradation i. e (crazes
and cracks) formation.

In this work, ZnO thin films were grown on sapphire (0001) substrate by
Pulsed Laser Deposition using SHG with Q-switched Nd:YAG pulsed laser operation
at 532nm in O2 gas ambient 5×10-2 mbar at different substrate temperatures varying
from room temperature to 500°C. The influence of the substrate temperature on the
structural and morphological properties of the films were investigated using XRD and
SEM. As result, at substrate 400°C, a good quality and crystalline films were deposited
that exhibits an average grain size (XRD) of 22.42nm with an average grain size
(SEM) of 21.31nm.

An Ellipsometric experimental set up of SOPRA ES4G type with a powerful
WVASE software for the theoretical calculus of the Ellipsometry parameters. The
Ellipsometry Technique can determine amplitude and phase information Ψ( and Δ)
dependent on wavelength range 250 nm to 900 nm (1.5 - 5 eV), including original
practical solutions, were developed. Encouraging results of TiO2 were obtained in
applying the simple Ellipsometric method of azimuths to determine the optical
constants for TiO2 with this optoelectronic device.

In this study, the optical and structure properties of MgxZn1-xO thin films is reported. The MgxZn1-xO thin films were prepared on Glass substrates by Q-switch second harmonic Nd:YAG laser deposition technigue with wavelength of 532nm from a ZnO target mixed with Mg of (0-0.3) wt% , and the films deposited at temperature (250°C).
The optical properties were characterized by transmittance and absorption spectroscopy measurements. For all the films the average transmission in the U.V (200-900) nm wavelength region was over 85% and the absorption edge shifted to a shorter wavelength as the magnesium concentration increased. The optical energy gap of MgxZn1-xO thin films, measured from transmittance spectra could be controlled between (3.3eV and 4.2eV) by adjusting magnesium concentration. X-ray diffraction was used to investigate the structure of the film. The refractive index of hexagonal MgxZn1-xO thin films decreases with the Mg concentration increase, such as at the wavelength of (500nm) the refractive index decreases from 1.93 to 1.85 as x increase from 0.15 to 0.3. The extinction coefficient and the complex dielectric constant were also investigate.

Thin films of copper sulfide (CuxS) were deposited at room temperature on glass substrates from solution containing copper (II) chloride, triethanolamine, and thiourea at appropriate pH (10-11). Two types of doping salts were used (AlCl3 & FeCl3) in four different weights (1, 1.5, 2, and 2.5) mg. The effect of introducing impurities and post-annealing was studied .The as-deposited films were found to
be amorphous, while the post annealed were polycrystalline. The changes in optical and electrical properties of doped films were also studied. The electrical conductivity was found to be highly dependent on annealing conditions, the resistivity of doped films was between (0.022-8.75) Ω cm. Optical band gaps of doped films determined from absorption spectra were found to have values within the range of (2.17-2.33) eV.

The morphological properties of the freshly and oxidized porous silicon at
oxidation time (60, 90) sec were studied. A blue emission from PSi can be seen with
eyes after thermal oxidation because the increasing of energy gab due to decreased
silicon column (nano particles).Pore size and shape of n-type wafers are estimate and
correlated with optical properties before and after rapid thermal oxidation (RTO).