Print ISSN: 1681-6900

Online ISSN: 2412-0758

Keywords : Nano

Effect of laser Fluence Energy on Morphological, Structural and Optical Properties of Gold and Silver Thin Films Prepared by Pulse Laser Deposition Method

Maha Al-Kinany; Ghaleb A. Al-Dahash; Jasim Al-Shahban

Engineering and Technology Journal, 2015, Volume 33, Issue 9, Pages 1561-1570

We report the growth and characterization of (Ag, Au) nanoparticles thin films deposition on a glass substrate by pulse laser deposition (PLD) method. The (Ag, Au) thin films prepared through different laser fluence (0.4, 0.6 and 0.7) J/cm2. The effect of laser fluence energy on the morphological, structural and optical properties were studied by XRD, AFM and UV-Visible spectrophotometer.
X-ray diffraction showed nanostructure, with dominated peak at 2θ values 38.3182° corresponding to (111) for silver and peak observed at 2θ values 38.2° which can be indexed to the (111) of face-centered cubic (fcc) structure for Au. Surface topography studied by atomic force microscopy revealed narrowed size distributions, with grain sizes ranging from 21.81 to 37.06 nm for Ag, and grain sizes ranging from 12.63 to 15.01nm for Au thin films. The results showed the Average gran Size increased with increasing laser fluence energy and RMS roughness increased with increasing laser fluence energy. Optical properties measurements showed that(Ag, Au) thin films have two peak the first one related with interband transitions, and the second peak formation of a surface plasmon peak (SPR). Optical properties measurements showed transformation from metallic properties of bulk (Ag, Au) to semiconductor properties when formed by sort of nanostructure evidenced by the formation of optical energy gap about (0.8, 0.7 and 0.5) eV when laser fluence increased (0.4, 0.6 and 0.7) J/cm2 respectively for Ag thin films. when grain size become smaller the optical energy gap increased. Optical energy gap(Eg) decreased (1.4, 1.2 and 0.8) eV when laser fluence increased (0.4, 0.6 and 0.7) J/cm2 respectively for Au thin films.

Investigate and Comparison Effect add Amorphous and Crystalline - Nano SiO2 on Properties of Concrete

Rami Joseph Aghajan Sldozian

Engineering and Technology Journal, 2015, Volume 33, Issue 3, Pages 547-555

In this paper, the study included the comparison between amorphous silica and crystalline silica (quartz), and with nano scale size, two types of silicawere added to concrete by ratios (5%, 10%, 15%, and 20%) as a replacement by the weight of cement. Destructive and non-destructive tests wereconducted on the specimens, the results show in destructive test the compressive and tensile strength increase in 15%wt addition ratio in both types of silica, but in amorphous silica was high than in quartz.The results of non-destructive tests show in (Schmidt Hammer) the 15% ratio in both kinds of silica show high hardness than other ratios. Ultra sonic (pules velocity) test, noted the better quality was in 15% ratio in amorphous silica and also show fastest pules velocity.

Effects of Nano-Fluids Types, Volume Fraction of Nano-Particles, and Aspect Ratios on Natural Convection Heat Transfer in Right- Angle Triangular Enclosure

Israa Y. Daood

Engineering and Technology Journal, 2010, Volume 28, Issue 16, Pages 5365-5388

This study investigates natural convection heat transfer and fluid flow
characteristic of water based nano-fluids in a right-angle triangular enclosure, where the left vertical wall is insulated, the right inclined wall is cooled, and the horizontal wall is heated by spatially varying temperature. Governing equations are solved using treamvorticity
formulation in curvilinear coordinates. Streamlines, isotherms, local and average Nusselt number, moreover to NUR factor are used to present the corresponding flow and thermal fields inside the triangular enclosure. Calculation were performed for three aspect ratio of enclosure geometry (AR=0.5, 1, 2), solid volume fractions of nanoparticles ranging from PHI=0, to 4%, and Rayleigh number varying from 104 to 106. Three types of nano-particles are taken into consideration: Cu, Al 2O3, and TiO2. The results show that, the average heat transfer rate increases significantly as particle volume
fraction and Rayleigh number increase. Also, the type of nano-fluid is a key factor for heat transfer enhancement where the high values are obtained when using Cu, TiO2, and Al2O3 nano-particles respectively. Finally, it is observed that the aspect ratio of the enclosure is one of the most important on flow and heat transfer. Increasing the AR leads
that to increase the flow strength and heat transfer rate.