Papers by Keyword: X-Ray Diffraction (XRD)

Abstract: The civil engineering projects that includes soft clay within its activities has a serious concern of hazards, such hazards can be overcame by treating the existing soils by certain materials which are named as "stabilizers". The common materials that are highly used in this field are ordinary Portland cement, fly ash, lime and rice husk ash, etc. Each one of these stabilizers has its known shortcomings. The alkali activation of any alumina silicate source produces some kind of cost effective primary binding gel which is known as "Geopolymers". This study is devoted to investigate the role of liquid over fly ash ratio to some soil – FA based Geopolymers geotechnical properties. Such ratio is taken as 2.71, 3.167, 3.8 and 4.75 respectively within the experimental program and the investigated geotechnical properties are the specific gravity, liquid and plastic limit, compaction characteristics and California bearing ratio. The tests results showed that the maximum dry density decreased about 42 % at 2.71 liq/FA whereas this the specific gravity decreased 27 % at the same this ratio. In addition, the 3.8 and 4.75 of such limits revealed no plastic behavior due to the high presence of liquid.

Abstract: In this study, Zinc oxide (ZnO) undoped and Lanthanum doped (ZnO: La) thin films were deposited on 400°C heated glass using spray pyrolysis technique with moving nozzle. The components (Zn (CH₃COO)2, 2H₂O) and (LaCl₃, 7H₂O) were used as sources to produce ZnO thin film and doped Lanthanum, respectively. Effects of dopant on the optical and structural properties of undoped and 0, 2 and 4 wt. % Lanthanum doped ZnO thin films were studied. Optical transmittance spectra of the films showed high transparency of about 98% in visible region. The optical gap for ZnO and 0, 2 and 4 wt. % La doped ZnO thin films were found to be in 3.25-3.28 [eV] range. The X-ray diffraction showed that the thin films have hexagonal wurtzite structure with a strong (002) as preferred orientation, whereas the crystalline size was ranged in 15.89-33.45 nm. The ZnO thin films are promising to be used a light emitting diodes, gas sensor and UV detectors applications.

Abstract: In this study, we report structural, morphological and optical properties of Fe-doped SnO₂ thin layers. Fe doping concentration has evaluated from 0 to 0.6 wt.%. XRD and SEM results revealed a polycrystalline structure for Fe-doped SnO₂ thin layers. The optical transmittance of all thin layers displayed high transparency reach to 80% in the visible region. The optical gap of these layers decreases from 3.87 to 3.58 eV. The grain sizes decrease from 35 to 30 nm. The electrical resistivity of layers increases from 1.2×10^-2 to 6.8×10^-2 Ω.cm.

Abstract: This article presents the elaboration of tin oxide (SnO₂) thin films on glass substrates by spray pyrolysis technique. Our interest is on the investigation of Effect solution concentration on the structural, optical and morphological properties of the films. Structural analysis by X-ray diffraction showed that the deposited films are polycrystalline in nature with a tetragonal structure having a preferential orientation along with (1 1 0) plane. SEM micrograph proved the existence of small cracks on the film surface, EDS confirmed the composition percentage ratio of Sn and O₂ and no trace of impurities could be detected. The spectrophotometer UV-Visible confirms that it is possible to get good transparent SnO₂ films with a transmission of 80 to 90% in the visible. The values of optical band gaps vary between 3.6 and 4.0 eV depending on the spraying solution concentration.

Abstract: The lead sulfur (PbS) as thin films were deposited on ordinary glass slides, for different deposition times ranging from 30 to 90 min, and for different molar concentrations of lead nitrate (0.01, 0.05, 0.075 and 0.1) mol / l, at ambient temperature of 55 ° C, using thiourea and lead nitrate as source of S2- and Pb2+ ions respectively and TEA as complexing agent. For different deposition times, the films grow preferentially along (200) direction. With increase in deposition time, and at fixed molar concentration the transmittance remained less than 30% and the optical band gap value decreases from 1.8 to 1.6 eV, while the crystallite size increases from 21.9 to 27.8 nm. For various molar concentrations of lead nitrate and with time deposition equal to 60 min, it was observed that the films grow preferentially along (111) or (200) directions, which depend on the molar concentration. Increasing the concentration of lead nitrate leads to decrease the energy gap from 1.58 to 1.37 eV and increase the crystallite sizes from 28.0 to 32.6 nm.

Abstract: The precipitation of two 6xxx (Al-Mg-Si) alloys with and without copper (Cu) and excess silicon (Si) has been investigated by using the differential scanning calorimetry (DSC), transmission electron microscopic (TEM) and X ray diffraction (XRD) analysis. The analysis of the DSC curves found that the excess Si accelerate the precipitation. The values of activation energies for each peak of DSC curves were determined by using Kissinger–Akahira–Sunose (KAS) and Boswell isoconversional methods. The alloy which has an excess Si and copper require larger activation energy for precipitation despite the acceleration of the precipitation by the excess Si. TEM observation result shows there is smaller size and higher density of precipitate in excess Si alloy than those of excess-free.

Abstract: In this work Zinc oxide thin films prepared by spray pyrolysis technique. A set of ZnO thin films were deposited with various deposition times, on glass substrate at 350 °C. The precursor solution is formed with zinc acetate in distilled methanol with 0.1 molarity. The deposition time was ranged from 2 to 8 min. The structural and optical properties of those films were examined by X-ray diffraction (XRD) and ultraviolet-visible spectrometer (UV). X-ray diffraction patterns of the ZnO thin films showed polycrystalline hexagonal wurtzite structure and the preferred orientation was along (002) plane when the grain size varied between 9.66 and 16.67nm. ZnO thin films were highly transparent in the visible with the maximum transmittance of 85% and the optical band gap was found between 3.25 and 3.28 eV.

Abstract: In this manuscript, the structural properties such as the distance inter-reticular of samples is studied, In the fact, four samples were used symbolized as follows: E tAg(Å), the only difference is the thickness of the Silver buffer layer (tAg= 0, 50, 100 and 150 Å) to find out how the thickness of this layer depends on the structural characteristics of the Iron thin layer, all samples are deposited using molecular beam epitaxy (MBE) at room temperature onto Si (100) substrate. The structural properties of all samples examined using X-ray diffraction method at small and high angles. The small angles X-Ray diffraction curves confirmed to us that there is a clear difference between the surface structure of the samples by varying the number of Kiessig Fringes, Also high angles X-Ray diffraction curves assured us this difference through the clear variation in the angular positions of the peaks of Bragg and the distances inter-reticular values from a sample to the other.

Abstract: The aim of this work is to study the difference between the crystalline phases of used fluxes and obtained slags after Shielded Metal Arc Welding (SMAW). It is well known that The weld pool solidifies into the weld metal while the lighter molten flux floats on the top surface and solidifies as a slag layer that can be easily removed .The effects of individual flux ingredients as well as their interaction effects on weld metal composition have been investigated in this paper. The mass concentrations between fluxes (FA, FB and FC) and slags (SA, SB and SC) summarize the physico-chemical behavior of elements transfer between base metal, filler metal, flux and slag forming during welding of pipelines by SMAW process. The analysis of different fluxes phases and slags by X-ray diffraction allowed to detect the presence of different crystalline phases, which were formed at low temperature (T <1000°C) heat treatments, and during fluxes confection. As for the slags, the presence of new crystalline phases which have been formed at high temperatures.

Abstract: The synthesis of Fe₂TiO₅ powders has been successfully performed by making use of Fe₂O₃ and TiO₂ powders. The Fe₂O₃ powder was obtained from local ironstone in Tanah Laut, South Kalimantan, while the TiO₂ powder was a commercial product. The Fe₂O₃ powder was obtained from the local ironstone through coprecipitation method on pH 5, followed by calcination at 800 °C for 1 hour. The synthesis of Fe₂TiO₅ powder was done by mixing the raw powders using Planetary Ball Mill method for 5 hours. Thermogravimetric dan Differential Thermal Analysis (TG-DTA) was performed to estimate the calcination temperature. The milled mixtures were then calcined at temperatures of 700 – 1100 °C. X-Ray Diffraction (XRD) data showed that Fe₂TiO₅ formation started at 800 °C with a weight fraction of 3.60 wt%. The XRD data also showed that at 1100 °C the Fe₂TiO₅ formation has completed. The crystallite size of Fe₂TiO₅ powders was 50 and 66 nm after calcination at 900 and 1100 °C, respectively.