- Optical properties of nanocrystalline magnesium aluminate spinel synthesized from industrial wastes
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In this work, magnesium aluminate spinel (MA) nanoparticles were synthesized via co-precipitation method using industrial wastes of magnesium and aluminum. The obtained powders were calcined at a temperature range of 650-1500°C. The calcined powders were characterized by XRD, FT-IR, DTA, FE-SEM and HR-TEM. XRD data illustrated that the spinel MA with a crystallite size of ～3.8 nm was formed at 650°C. Optical properties of the MA spinel revealed that the optical reflectance is highly dependent on calcination temperature. Photoluminescence analysis revealed intrinsic emission bands with high intensity centered at 390, 370 and 485 nm, when the samples are excited by a 350 nm light from a Xe lamp at room temperature. Results suggest that co-precipitation method of aluminum and magnesium wastes at low temperatures is a promising way for the production of highly pure and active nanocrystalline MA spinel with expected unique properties.
- Ewais, Emad M.M.,Besisa, Dina H.A.,El-Amir, Ahmed A.M.,El-Sheikh, Said M.,Rayan, Diaa E.
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- Synthesis and characterization of nanocrystalline Nd3+-doped gadolinium scandium aluminum garnet powders by a gel-combustion method
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Nd3+-doped gadolinium scandium aluminum garnet (Nd:GSAG) precursor was synthesized by a gel combustion method using metal nitrates and citric acid as raw materials. The structure and morphology of the precursor and the sintered powders were studied by means of X-ray diffraction (XRD), infrared spectroscopy (IR) and transmission electron microscopy (TEM). The results showed that the precursor transformed into pure GSAG polycrystalline phase at about 800 °C, and the powders sintered at 800-1000 °C were well-dispersed with average particle sizes in the range of 30-80 nm. Optical properties of Nd:GSAG nano-powders were characterized by using photoluminescence spectroscopy. The highest photoluminescence intensity was achieved for the powder sintered at 900 °C.
- Su, Jing,Miao, Ju-Hong,Xu, Lin-Hua,Ji, Yu-Qing,Wang, Chu-Qin
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p. 1709 - 1712
(2012/06/30)
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- Block Coordination Copolymers
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The present invention provides compositions of crystalline coordination copolymers wherein multiple organic molecules are assembled to produce porous framework materials with layered or core-shell structures. These materials are synthesized by sequential growth techniques such as the seed growth technique. In addition, the invention provides a simple procedure for controlling functionality.
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- Catalyst compositions and the use thereof in the hydrogenation of carboxylic acid esters
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Disclosed are catalyst compositions comprised of the oxides of copper, zinc, and a third element selected from the group consisting of aluminum, magnesium, zirconium, and mixtures thereof, and the use of such catalyst compositions in the hydrogenation of carbonyl compounds such as carboxylate esters to obtain the alcohol corresponding to the acid residue of the ester.
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