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Abdel Alsmadi

Bio: Abdel Alsmadi is an academic researcher from Kuwait University. The author has contributed to research in topics: Magnetization & Magnetoresistance. The author has an hindex of 10, co-authored 46 publications receiving 446 citations. Previous affiliations of Abdel Alsmadi include Argonne National Laboratory & New Mexico State University.

Papers
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TL;DR: In this paper, the magnetic properties and their temperature dependencies of Co-Ti and Ru-Ti substituted barium ferrite nanocrystalline particles with ball milling method were studied.
Abstract: Co-Ti and Ru-Ti substituted barium ferrite nanocrystalline particles BaFe12−2xCoxTixO19 with (0≤x≤1) and BaFe12−2xRuxTixO19 with (0≤x≤0.6) were prepared by ball milling method, and their magnetic properties and their temperature dependencies were studied. The zero-field-cooled (ZFC) and field-cooled (FC) processes were recorded at low magnetic fields and the ZFC curves displayed a broad peak at a temperature TM. In all samples under investigation, a clear irreversibility between the ZFC and FC curves was observed below room temperature, and this irreversibility disappeared above room temperature. These results were discussed within the framework of random particle assembly model and associated with the magnetic domain wall motion. The resistivity data showed some kind of a transition from insulator to perfect insulator around TM. At 2 K, the saturation magnetization slightly decreased and the coercivity dropped dramatically with increasing the Co-Ti concentration x. With Ru-Ti substitution, the saturation...

103 citations

Journal ArticleDOI
TL;DR: In this article, the effect of Co doping on the structural, magnetic and optical properties of ZnO nanocrystalline particles, using X-ray diffraction, x-ray photoelectron spectroscopy (XPS), Quantum Design PPMS-9 magnetometry, and Ultra Violet-Visible (UVVisible) spectroglobalization, was carried out.

87 citations

Journal ArticleDOI
TL;DR: The structural, optical and magnetic properties of Mn doped ZnO nanocrystalline particles, Zn1-xMnxO, with different percentages of Mn content have been studied in this paper.
Abstract: The structural, optical and magnetic properties of Mn doped ZnO nanocrystalline particles, Zn1-xMnxO, with different percentages of Mn content have been studied. XRD and XPS measurements showed that all samples with Mn doping up to x = 0.1 possess typical wurtzite structure and have no other impurity phases. The incorporation of Mn ions into the ZnO lattice was also confirmed by FTIR and UV–Vis. spectroscopy results. Both XRD and SEM results indicated a slight decrease in the grain size with increasing the Mn doping level. The XPS results indicated an increase in the oxygen vacancies concentration with increasing the Mn doping level. The magnetization measurements revealed a weak ferromagnetic behavior at room temperature and a clear ferromagnetic behavior with relatively large coercive fields at low temperature. The ferromagnetic order is improved by increasing the Mn doping. In addition, we observed an increase in the concentration of oxygen vacancies, which is also induced by increasing the Mn doping level. A ferromagnetic coupling of the local moment of Mn dopants through the sp-d exchange interaction and oxygen vacancies, in addition to different magnetic contributions due to different forms of Mn ions that coexist in the Mn doped nanoparticles were presented in order to interpret the observed magnetic behavior. We observed a clear red shift in the direct band gap and an increase in the coercive field and saturation magnetization values with increasing the Mn doping level.

82 citations

Journal ArticleDOI
TL;DR: In this article, the effect of substitution of Ti2 and Ru4+ ions for Fe3+ ions on the structural and magnetic properties of strontium ferrite nanoparticles with ( 0 ≤ x ≤ 0.3 ), using x-ray diffraction, Quantum Design PPMS-9 magnetometry, and electrical resistivity.

54 citations

Journal ArticleDOI
TL;DR: In this article, the authors synthesized Ni doped ZnO thin films, ZnxNi1-xO ( 0.0 ≤ x ≤ 0.1 ), using spray pyrolysis deposition and performed a systematic study on their crystal structure, electronic, photoluminescent properties, and magnetic order.

43 citations


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01 Sep 1955
TL;DR: In this paper, the authors restrict their attention to the ferrites and a few other closely related materials, which are more closely related to anti-ferromagnetic substances than they are to ferromagnetics in which the magnetization results from the parallel alignment of all the magnetic moments present.
Abstract: In this chapter, we will restrict our attention to the ferrites and a few other closely related materials. The great interest in ferrites stems from their unique combination of a spontaneous magnetization and a high electrical resistivity. The observed magnetization results from the difference in the magnetizations of two non-equivalent sub-lattices of the magnetic ions in the crystal structure. Materials of this type should strictly be designated as “ferrimagnetic” and in some respects are more closely related to anti-ferromagnetic substances than they are to ferromagnetics in which the magnetization results from the parallel alignment of all the magnetic moments present. We shall not adhere to this special nomenclature except to emphasize effects, which are due to the existence of the sub-lattices.

2,659 citations

Journal ArticleDOI
TL;DR: In this paper, facile cobalt-doping based on Co-modified MoOx-amine precursors is developed to optimize the electrochemical hydrogen evolution reaction (HER) over Mo2C nanowires.
Abstract: Efficient hydrogen evolution reaction (HER) over noble-metal-free electrocatalysts provides one of the most promising pathways to face the energy crisis Herein, facile cobalt-doping based on Co-modified MoOx–amine precursors is developed to optimize the electrochemical HER over Mo2C nanowires The effective Co-doping into Mo2C crystal structure increases the electron density around Fermi level, resulting in the reduced strength of Mo–H for facilitated HER kinetics As expected, the Co-Mo2C nanowires with an optimal Co/Mo ratio of 0020 display a low overpotential (η10 = 140 and 118 mV for reaching a current density of –10 mA cm−2; η100 = 200 and 195 mV for reaching a current density of –100 mA cm−2), a small Tafel slope (39 and 44 mV dec−1), and a low onset overpotential (40 and 25 mV) in 05 m H2SO4 and 10 m KOH, respectively This work highlights a feasible strategy to explore efficient electrocatalysts via engineering on composition and nanostructure

382 citations

01 Jan 2013
TL;DR: In this article, the authors discuss p-type ZnO materials: theory, growth, properties and devices, comprehensively, and summarize the growth techniques for p- type ZnOs.
Abstract: Abstract In the past 10 years, ZnO as a semiconductor has attracted considerable attention due to its unique properties, such as high electron mobility, wide and direct band gap and large exciton binding energy. ZnO has been considered a promising material for optoelectronic device applications, and the fabrications of high quality p-type ZnO and p–n junction are the key steps to realize these applications. However, the reliable p-type doping of the material remains a major challenge because of the self-compensation from native donor defects (V O and Zn i ) and/or hydrogen incorporation. Considerable efforts have been made to obtain p-type ZnO by doping different elements with various techniques. Remarkable progresses have been achieved, both theoretically and experimentally. In this paper, we discuss p-type ZnO materials: theory, growth, properties and devices, comprehensively. We first discuss the native defects in ZnO. Among the native defects in ZnO, V Zn and O i act as acceptors. We then present the theory of p-type doping in ZnO, and summarize the growth techniques for p-type ZnO and the properties of p-type ZnO materials. Theoretically, the principles of selection of p-type dopant, codoping method and X Zn –2V Zn acceptor model are introduced. Experimentally, besides the intrinsic p-type ZnO grown at O-rich ambient, p-type ZnO (MgZnO) materials have been prepared by various techniques using Group-I, IV and V elements. We pay a special attention to the band gap of p-type ZnO by band-gap engineering and room temperature ferromagnetism observed in p-type ZnO. Finally, we summarize the devices based on p-type ZnO materials.

308 citations

Posted Content
TL;DR: In this article, the enhancement of ferromagnetism in pure ZnO upon thermal annealing with the ferromagnetic transition temperature Tc above room temperature has been reported.
Abstract: We report here enhancement of ferromagnetism in pure ZnO upon thermal annealing with the ferromagnetic transition temperature Tc above room temperature. We observe a finite coercive field upto 300K and a finite thermoremanent magnetization upto 340K for the annealed sample. We propose that magnetic moments can form at anionic vacancy clusters. Ferromagnetism can occur due to either superexchange between vacancy clusters via isolated F+ centers, or through a limited electron delocalization between vacancy clusters. Isolated vacancy clusters or isolated F+ centers give rise to a strong paramagnetic like behaviour below 10K.

274 citations

Journal ArticleDOI
TL;DR: In this article, the authors evaluate the development of TiO2-and ZnO-based photocatalysts made through hydrothermal, sol-gel and flame spray pyrolysis processes.

169 citations