Browsing by Author "Ataalla M."

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    Determination of the sensing characteristics of SiO2-Bi2O3-TiO2 system towards relative humidity
    (2018-01-01) Afify A.S.; Slavov S.S.; Mahmoud A.E.R.; Hassan M.; Ataalla M.; Staneva A.; Mohamed A.
    The aim of the present study is to determine the relative humidity (RH) sensing characteristics of the glass and glasscrystalline materials based on SiO2-Bi2O3-TiO2 system prepared by the melt quenching and controlled glass crystallization methods. Sensors were obtained by screen-printing of the prepared compositions onto alumina substrates with Pt electrodes. The sensors were tested in the range (0.0 - 96%) of the relative humidity at room temperature. The results have shown that most of the obtained glass ceramic materials had a lower sensitivity towards RH. The composition 20SiO2.30Bi2O3.50TiO2 has possessed the highest permittivity value (3000 F.m-1) and the lowest value of dielectric loss (0.0002) at room temperature which make it a promising candidate for some industrial applications such as energy storage, electronic capacitors as well as memory devices.
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    Glass formation and structure of glasses in the ZnO-WO3-La2O3-Al2O3 system
    (2015-01-01) Ataalla M.; Milanova M.; Aleksandrov L.; Iordanova R.; Staneva A.; Dimitriev Y.
    The glass formation region in the section 90(xZnO.yWO3.zLa2O3).10Al2O3 of a constant Al2O3 content of 10 mol % and varying amounts of WO3, ZnO and Nd2O3 from ZnO-WO3-La2O3-Al2O3 system is determined by the melt quenching technique (with cooling rates of 10 Ks-1 - 102 Ks-1). The glasses are obtained from compositions of a high WO3 content (60 mol % - 75 mol %). The amorphous state of the samples is verified by X-ray diffraction (XRD). The thermal parameters of the investigated glasses are obtained by differential thermal analysis (DTA). The glass transition temperature (Tx) is in the range 440°C - 510°C, while the crystallization temperature (Tg) varies from 520°C to 650°C. The glasses are characterized by a good thermal stability in respect to crystallization. ΔT varies in the range of 60°C - 135°C (ΔT = Tx-Tg). The glasses structure is studied by IR spectroscopy. It is established that the amorphous network is built up mainly by WO6 octahedra connected through W-O-W bridges.
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    Preparation and characterization of a zinc oxide nanopowder supported onto inorganic clay
    (2016-01-01) Hassan M.; Afify A.S.; Ataalla M.; Mohammed A.; Staneva A.; Dimitriev Y.; Tulliani J.M.
    Zinc oxide nanoparticles are obtained by a wet chemical method using zinc sulphate as a raw material. Doping sepiolite, micro-fibrous inorganic clay, with ZnO after precipitation under basic conditions and subsequent thermal treatment is investigated as both materials are abundant. They are used for the development of humidity and gas sensors of great environmental importance. The particle size distribution, the morphology and the composition of the powder samples are characterized by X-Ray diffraction accompanied by Field Emission Scanning Electron Microscopy and High Resolution-Transmission Electron Microscopy techniques. The data obtained confirm the formation of zinc oxide nanoparticles of a size of 10 nm on the modified sepiolite grains.
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    STRUCTURE, THERMAL, AND PHYSIC-CHEMICAL PROPERTIES OF SOME CHALCOGENIDE ALLOYS
    (2023-01-01) Adam A.M.; Abdel-Rehim W.M.F.; Petkov P.; El-Qahtani Z.M.H.; Alqannas H.S.; Alruqi A.B.; Hakamy A.; Ataalla M.
    Bulk products of crystalline Bi2Se3-xTex alloys (x =0.0, 0.1, 0.3, 0.5) were pre-pared using simple melting synthesis. Crystalline features, microstructure, and surface morphologies of the synthesized samples were examined via X-ray dif-fraction, scanning electron microscope, and energy dispersive X-ray spectrome-ter. Elemental distribution was studied by energy dispersive analysis of X-ray spectroscopy. Polycrystalline of rhombohedral crystal structure was observed for the concerned samples. Perfect crystallinity and micro-scalability of the prepared were also reflected by the physic-chemical properties of each sample. Thermal behavior was studied throughout differential scanning calorimetry and thermo-gravimetric analysis showing that the samples are of high stability over high temperature range. Physic-chemical properties were determined in terms of ex-perimental density. These properties were compactness value, molar volume and the percentage of free volume. Density of Bi2Se3 alloy was obtained at 7.37 gm/cm3. The Te doping enhanced the density of the Bi2Se3-xTex system. The most Te doped alloy showed density of 9.018 gm/cm3. All other physic-chemical prop-erties showed strong dependence on the Tea amounts in the system.