Roles of Cobalt Doping on Structural and Optical of ZnO Thin Films by Ultrasonic Spray Pyrolysis

Here we report a systematic study of structural, optical, and magnetic measurements of Zn1-xCoxO (x = 0–0.22 at.%) by Ultrasound pyrolysis spray technique. The hexagonal wurtzite structure of our films is confirmed by X-ray diffraction with an average crystallite size estimated in the range of 18–30 nm. For the optical proprieties, using the Levenberg–Marquardt least squares rule, the experimental transmission measurements were perfectly adapted to the transmission data calculated by a combination of the Wemple-DiDomenico model, the absorption coefficient of an electronic transition and the Tauc-Urbach model. The concentration of the NCo absorption centers and the oscillator intensity f of the d-d transition of Co2+ ions are determined by the Smakula method. The presence of high concentrations of localized states in the thin films is responsible for the reduction in the width of optical bandgap

Rôle des transferts thermiques sur la corrosion des concentriques utilisés dans les puits producteurs d’eau albienne

L’eau de l’aquifère albien de la région de Haoud‑Berkaoui est utilisée à grande échelle et à des fins variées dans le Bas‑Sahara algérien, notamment dans le domaine de l’extraction pétrolière. Pour améliorer les conditions d’exploitation de l’eau souterraine, des concentriques ont été installés au sein des puits producteurs pour l’acheminement d’inhibiteurs de corrosion. La durée de vie de ces concentriques, prévue initialement pour cinq années, a été réduite à seulement deux ans, des fuites importantes d’eau ainsi que des dégradations au niveau des têtes de puits ayant été constatées.Les analyses chimiques des échantillons d’eau de plusieurs forages montrent que ces derniers sont de nature incrustante, chargés en sulfates, peu riches en gaz carbonique dissous et ne contiennent pas de H2S ni d’oxygène. Il a été possible, par thermométrie, de mettre en évidence l’existence d’un gradient de température, variable en fonction de la profondeur et pouvant atteindre 16 °C.La corrosion du concentrique sous transfert thermique a été examinée à l’aide des techniques électrochimiques. La vitesse de corrosion augmente considérablement en fonction du gradient de température croissant, quelle que soit la nature de l’eau (ayant ou non subi un traitement préalable par bactéricides et inhibiteurs). La meilleure efficacité des traitements employés a été obtenue pour un gradient nul et n’atteint que 30 %. L’absence totale de FeS élimine toute possibilité de corrosion d’origine bactérienne, le gradient de température semble favoriser l’accélération de la cinétique d’échange entre le métal et l’eau.The Haoud-Berkaoui region comprises three producing oil fields: Haoud-Berkaoui, Benkahla and Guellala, all located 100 km west of Hassi-Messaoud (Algéria). Oil is recovered from this heterogeneous medium sized layer by injecting water under pressure into the geological formations; the water is extracted from the Albien aquifer by 15 producing wells. To improve exploitation conditions and to increase injection capacities of this water, concentrics were installed within the producing wells to introduce anti-corrosion products. The life time of these facilities, initially predicted to be five years, has been reduced to only two years; important water leaks as well as deterioration of the wellheads have been noticed. The concentrics in the producing wells were in a very advanced state of corrosion, with apparent holes.Chemical analyses of water samples taken from several wells showed that their ion concentrations varied from 107 to 258 mg•L‑1 for calcium, 73 to 139 mg•L‑1 for magnesium, 24 to 36 mg•L‑1 for potassium, 282 to 304 mg•L‑1 for sodium, 459 to 648 mg•L‑1 for chlorides, while bicarbonate concentrations varied from 116  to 176 mg•L‑1. The water from these wells is generally hard, rich in sulphates, but poor in dissolved CO2 gas and lacking H2S and oxygen. The pH was neutral or slightly basic with values ranging between 7.02 and 7.58.A temperature gradient (∆T) was measured along the depth of the well, variable with depth, with a maximum gradient of 16 °C. The temperature gradient profile showed that ∆T was small at the surface of the well and then increased considerably at 584 m depth. For depths between 584 m and 984 m, ∆T was somewhat attenuated but remained high. It is in this zone that the concentric was most affected by corrosion.The corrosion of the concentric in an Albien medium under heat transfer was examined using electro-chemical techniques. The rate of corrosion increased sharply with increasing temperature, regardless of the water quality (i.e., treated with anti-bacterial or anti-corrosion agents, or not). These thermal effects are attributed to the acceleration of kinetic exchange reactions between the metal and the solution and are mainly linked to the energetic contribution associated with the heat flux crossing the concentric by conduction and convection.The efficiency of the anti-corrosion treatments was evaluated using the equation % E = 100 (Vcorr-V’corr)/Vcorr, where Vcorr and V’corr are the rates of corrosion with and without treatment, respectively. The best treatment efficiency of 30 % was obtained at a zero temperature gradient. The total absence of FeS eliminated the possibility of bacterial corrosion; the sulfato-reducing bacterium effect was eliminated by the bactericidal treatment

Air and Vacuum Annealing Effect on the Highly Conducting and Transparent Properties of the Undoped Zinc Oxide Thin Films Prepared by DC Magnetron Sputtering

In this study, we aim to investigate the effect of zinc interstitials (Zni) and oxygen vacancies (VO) on the ZnO electrical conductivity. ZnO films were synthesized via DC magnetron sputtering process using pure Zn target in gases mixture of Ar/O2 = 80/17.5 (sccm). In order to improve the optical and electrical prosperities, the obtained films were subjected to air and vacuum annealing treatment. Several techniques such as field emission scanning electron microscopy (FESEM), Grazing Incidence X-ray Diffraction (GIXRD), Raman spectroscopy, photoluminescence spectroscopy (PL) and UV-visible were used to study the influence of heat treatment on structural and physical properties of ZnO films. Electrical conductivity of ZnO thin films was determined by measuring the sheet resistance and thickness of the films.  XRD results confirm the synthesis of annealed ZnO films of the hexagonal structure with a preferential orientation along the (002) plane. The average crystallite size is altered between 22.6 to 28.4 nm dependent on the plan orientation of the ZnO film. Morphology and crystallinity of the ZnO structure could efficiently control the transmittance, electrical resistivity and optical band gap. As deposited ZnO film showed a lower electrical resistivity of 2.72×10-3 Ωcm due to the Zn-rich conditions. Under vacuum annealing, a combination of low resistivity (1.17×10-2 Ωcm) and better optical transmittance (87 %) are obtained. ZnO films developed in this study with high transmittance and low resistivity and good electro-optical quality supports their use in transparent and conductive electrode applications. The plan presentation was visualized using Vesta, with the lattice parameter set as follows: a = b = 3.249 Å; c = 5.207 Å; α = β = 90°; γ = 120°. Based on the construction and optimization of primitive cells, the supercells were constructed and then optimized. Finally, (002) and (103) planes were cut and the planar supercell structure was constructed. In order to make a plane representation for the solid bulk with 10 Å of thickness

The effectiveness of teaching according to Marzano's learning dimensions model in the development of mathematics achievement among primary school students

هدفت الدراسة للكشف عن فاعلية نموذج أبعاد التعلم لـ (مارزانو) في تنمية تحصيل الرياضيات لدى تلاميذ الطور الثالث من مرحلة التعليم الابتدائي. وللتحقق من هدف الدراسة اعتمد الباحث المنهج التجريبي بتصميم مجموعتين (تجريبية وضابطة) مع القياس القبلي و البعدي، طبقت الدراسة على عينة قوامها (199) تلميذا، منها (133) مجموعة تجريبية و (66) مجموعة ضابطة. و أُعِد دليلا للمعلم وعُرِض على مجموعة من الأساتذة في علوم التربية للتأكد من صدق المحتوى ومن خلال معادلة (Lawchi) اثبت صلاحيته. كما أعتمد نتائج الاختبارات الفصلية المعدة وفق النموذج المعتمد في امتحان نهاية مرحلة التعليم الابتدائي. توصلت الدراسة إلى. عدم وجود فروق ذات دلالة إحصائية بين المجموعتين(التجريبية والضابطة) في تحصيل الرياضيات في الاختبار القبلي. ووجود فروق ذات دلالة إحصائية بين القياسين (القبلي و البعدي) في تحصيل الرياضيات لدى المجموعة التجريبية لصالح الاختبار البعدي. كما تأكدت فاعلية التدريس وفق نموذج أبعاد التعلم لـ (مارزانو) من خلال اختبار ايتا.The study aimed at detecting the effectiveness of Marzano's learning dimensions model in the development of mathematics achievement among the third year primary school students .In order to achieve the objective of the study, the researcher adopted an experimental method by designing two groups (experimental and controlgroup) along with a pre-test and post-test measurement.The study was applied on a sample of (199) students; (133) experimental groups, (66) control group. A teacher's guide was prepared and presented to a group of education sciences teachers to ensure the validity of the content and through the (Lawchi) equation, which proved its validity.The results of the examinations were based on the model adopted at the end of primary education exam.The study indicated:. There were no statistically significant differences between the two groups (experimental and control) in the achievement of mathematics in the pre-test.. There were statistically significant differences between the two groups (experimental and control) in the achievement of mathematics in the post-test.-There were statistically significant differences between the two groups (experimental and control) in the achievement of mathematics in the post-test. There was statistically significant differences between (pre-test and post-test) in the achievement of mathematics in the experimental group in favor of the post-test.The effectiveness of teaching according to the Marzano dimensions of learning model has been confirmed by the ETA test

Interactions between the mississippi choctaw and european americans through the sport of toli

Pure and doped Zn1−xMgxO films were deposited onto glass substrate by ultrasonic spray pyrolysis technique. The variation of lattice constant and the blue shift of near-band-edge emission indicate that Zn2+ ions are successfully substituted by Mg2+ ions within ZnO lattice. At higher Mg content (x ≥ 0.21), a drastic change appears in the morphology, as a result of structural changes from wurtzite (ZnO) structure into a mixture of wurtzite and cubic (MgO) phases. FTIR study indicated the existence of distinct characteristic absorption peaks at ~442 cm−1 for Zn–O stretching mode that shifted toward the red region with the increase in Mg content. In addition to the host phonons of ZnO, one additional band was observed around 523 cm−1, presumably attributed to the Mg-related vibrational mode. The optical constants and thickness of thin films have been determined using experimental transmittance data. The luminescence intensity at 2.63 eV of Zn0.85Mg0.15O thin films was found to be approximately 13 times higher than that of pure ZnO film measured under the same excitation condition

Electrical and Structural properties of Cu2O thin films deposited at different temperatures by magnetron sputtering

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Effect of Solution Concentration on ZnO/ZnAl₂O₄ Nanocomposite Thin Films Formation Deposited by Ultrasonic Spray Pyrolysis on Glass and Si(111) Substrates

International audienceA complex ZnO/ZnAl2O4 heterostructures thin films on glass and Si (111) substrates have been successively obtained by a soft ultrasonic spray pyrolysis (USP) method deposition using the Zn/Al molar ratios concentrations of 0.07/0.13 and 0.1/0.1, respectively. According to (XRD) an ordered zinc oxide (ZnO) and zinc aluminate (ZnAl2O4) structures deposited onto glass from the air annealing at 500 °C during 2 hours was observed and confirmed by the (EDX), (FTIR) and Raman spectroscopy techniques. The estimated crystallites size and stress values of ZnO and ZnAl2O4 in the ZnO/ZnAl2O4 /glass film were 19 nm/0.469 GPa and 11 nm/-0.292 GPa, respectively. The lower Zn/Al molar ratio around 0.035/0.06 produced only ZnO as a single phase, suggesting the Al insufficient quantity. The Si (100) substrate with 0.07 Zn molarity conducted to the Zn2SiO4/ZnO/ZnAl2O4 composite. The Raman integrated intensity bands of ZnO and ZnAl2O4 increases with increasing Zn to Al molar ratio (0.1/0.1 comparatively to 0.07/0.13). The ZnO&ZnAl2O4 crystallinity enhances as Zn molarity increases. The ZnO films in the composites grow with (002) texture. The TC( hkl ) value indicated that ZnAl2O4 in the ZnO/ZnAl2O4/glass layer is polycrystalline preferentially oriented along the (311) plane. Spinel ZnAl2O4 oxide onto Si (111) substrate grown according to the (220) orientation. Crystallites are larger in ZnO/ZnAl2O4 /Si than in ZnO/ZnAl2O4 /glass. The ZnO/ZnAl2O4 film onto glass substrate is transparent in the visible and near infrared regions and sensitive to UV absorption, as characterized by UV-Vis spectroscopy. The ZnO and ZnAl2O4 E g values in the ZnO/ZnAl2O4 /glass composite were 3.25 and 3.88 eV, respectively

A New Automated Trigger Circuit for a Pulsed Nd: YAG Laser

Abstract. The power supply of flash lamp-pumped a Nd: YAG solid-state laser basically consists of a trigger circuit which initiate the ionization of the gas into the lamp, a simmer circuit that keeps the ionized gas with a low-level dc current and a main discharge circuit where a storage capacitor is discharged into a flash lamp to pump the Nd:YAG laser. The impedance of the flash lamp presents a nonlinear variation and the gas deionization which can occur between two pulses laser, leading to another manual triggering operation. To overcome this operation, we give in this paper a new automated trigger circuit activated by a delivered signal from the simmer circuit. This circuit is simple for implementation and need just few components. It has been simulated by PSpice software and validated by experimental results

Effect of Cement on the Drying–Wetting Paths and on Some Engineering Properties of a Compacted Natural Clay from Oran, Algeria

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