Vasily I Lutsyk; Vera P Vorob’eva; Anna E Zelenaya
Abstract
The T-x-y-z diagrams of quaternary Na2MoO4-Na2CrO4-Na2WO4-Na2SO4, Fe-Ni-Co-Cu, Pb-Cd-Bi-Sn systems and their four-dimension (4D) computer models are considered. Geometric constructions of these diagrams are described by special di-, uni- and invariant states schemes. Assumed liquidus of the Fe-Ni-CoFeS-NiS-CoS ...
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The T-x-y-z diagrams of quaternary Na2MoO4-Na2CrO4-Na2WO4-Na2SO4, Fe-Ni-Co-Cu, Pb-Cd-Bi-Sn systems and their four-dimension (4D) computer models are considered. Geometric constructions of these diagrams are described by special di-, uni- and invariant states schemes. Assumed liquidus of the Fe-Ni-CoFeS-NiS-CoS subsystem T-x-y-z diagram on the basis of the data about the structure of the border systems is predicted and the 4D computer model is designed. The possibilities of calculating of three- (3D) and two-dimensional (2D) iso- and polythermal sections are shown.
Kalawati Saini; Pravin P. Ingole; Smriti Sharma Bhatia; Nutan Rani
Abstract
Copper and copper oxide (Cu2O) nanoparticles (NPs) were synthesized by electrochemical route using 2.55 mM tri-sodium citrate (TSC) as a capping and reducing agent. Synthesis was conducted at 15 V and 373 K in the presence of pH 4.22 using a copper rod as a working electrode and a platinum wire as a ...
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Copper and copper oxide (Cu2O) nanoparticles (NPs) were synthesized by electrochemical route using 2.55 mM tri-sodium citrate (TSC) as a capping and reducing agent. Synthesis was conducted at 15 V and 373 K in the presence of pH 4.22 using a copper rod as a working electrode and a platinum wire as a reference electrode. The electrochemical set-up was kept in the air, as well as under inert nitrogen-purged conditions. Cu NPs were synthesized for the first time by the direct dissolution of Cu 2+ into the solution of the capping agent from the copper electrode in to the electrochemical cell. This means salt of copper was not used. NPs were characterized using UV–visible absorption spectroscopy, transmission electron microscopy (TEM), and X-ray diffraction (XRD) techniques. High-resolution TEM pictures showed the formation of a rod-shaped nanostructure. The lengths of copper rods were from 56.9 nm to 61.9 nm and the widths of nano-rods were, from 8.11 nm to 9.57 nm. Furthermore, the rod-shaped Cu2O NPs were tested for their catalytic applications in the electro-oxidation of methanol, where they showed excellent activity in terms of higher efficiency as well as kinetically low over-potential values.
Yasaman Kolvandi; Mohammad Aghagholizadeh; Saeed Sheibani
Abstract
In this paper, the possibility of production of Cu matrix nano-composite powder containing 10, 37 and 54 wt.% NiO using mechano-chemical reduction of different copper oxides (CuO and Cu2O) was studied. Structural evolutions were characterized by X-ray diffraction. Also, the microstructure was characterized ...
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In this paper, the possibility of production of Cu matrix nano-composite powder containing 10, 37 and 54 wt.% NiO using mechano-chemical reduction of different copper oxides (CuO and Cu2O) was studied. Structural evolutions were characterized by X-ray diffraction. Also, the microstructure was characterized by scanning electron microscopy and transmission electron microscopy. Particular attention has been paid to the reaction mechanism and kinetics using differential scanning calorimetry. It was found that the reactions completed gradually between 5 to 22h of milling. Formation of Cu2O and Cu(Ni) solid solution, as intermediate phases, were observed during the reaction. It was found that, the initial excess Cu delayed reduction reaction and decreased the final crystallite size up to 18nm. Microstructural results showed that relatively large nano-composite agglomerates powder composed of uniform dispersion of NiO nano-particles in nano-crystalline Cu matrix were obtained. Kinetic study revealed that CuO reduction to Cu through two-steps reaction with lower activation energies in each step had higher rate, compared to one-step reduction of Cu2O.
Tetsuo Umegaki; Yoshiyuki Kojima; Kohji Omata
Abstract
He present study investigated the effect of silica coating on catalytic activity of copper-zinc oxide based catalyst for methanol synthesis. Silica coated catalysts prepared using ammonia and L(+)-lysine as promoters of silica coating shows almost same specific surface area and pore size distribution ...
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He present study investigated the effect of silica coating on catalytic activity of copper-zinc oxide based catalyst for methanol synthesis. Silica coated catalysts prepared using ammonia and L(+)-lysine as promoters of silica coating shows almost same specific surface area and pore size distribution compared with pristine commercial copper-zinc oxide based catalyst, while silica coated catalyst prepared using L(+)-arginine shows significantly lower specific surface area than the pristine catalyst and its mesopores and macropores disappear. Silica coated using ammonia and L(+)-lysine weakly bonds to the commercial catalyst without loading into pores of the catalyst, while silica using L(+)-arginine strongly bonds to the catalyst with loading into the pores of the catalyst. Reduction temperature of fine copper species of the silica coated catalysts shifts to the higher temperature than that of the pristine catalyst, and shift temperatures of the silica coated samples prepared using ammonia and L(+)-lysine are lower than that of the sample prepared using L(+)-arginine, indicating that strongly bonding silica prevents reduction of fine copper species in the commercial catalyst. Among the silica coated catalysts, the coated catalyst prepared with ammonia shows highest COx conversion, and the catalytic activity increase with the decrease of weight ratios of silica to catalyst.
J. A. Wani; N. S. Dhoble; S. J. Dhoble
Abstract
Very little data on copper co-doped CaSO4: Dy and CaSO4: Dy, P phosphors seems to have been reported so far. In the present study the influence of copper and rare earths co-doping on thermoluminescence intensity of CaSO4: Dy, P phosphor has been investigated. Acid evaporation re-crystallization method ...
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Very little data on copper co-doped CaSO4: Dy and CaSO4: Dy, P phosphors seems to have been reported so far. In the present study the influence of copper and rare earths co-doping on thermoluminescence intensity of CaSO4: Dy, P phosphor has been investigated. Acid evaporation re-crystallization method was adopted for the synthesis purpose. Phosphors were characterized by scanning electron microscopy (SEM), photoluminescence (PL) and thermoluminescence (TL) techniques. Results obtained through this study are of mixed nature. In some cases, TL intensity is either greater or nearly equal to standard CaSO4: Dy while in other cases it is half or rather weak in comparison to standard CaSO4: Dy phosphor. Copper was found to suppress temperature peak structure above 300 o C. SEM micrographs of CaSO4: P, Dy, Cu, RE phosphors show that the particle size is in the micrometer range, 1 to 5 µm approximately. The systematic study carried out in this work is solely novel as no such report existed before. From this study it is clear now that by co-doping multi-impurities simultaneously to enhance TL characteristics of CaSO4: Dy phosphor is no longer useful because it proved otherwise.
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