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[en] The role of polyol, precursor and reaction promoting agents in the synthesis of metal and alloy nanoparticles using polyol process has been investigated by analyzing the reaction steps involved in the synthesis of cobalt in Co ion-polyol-[OH-] ion system in detail. The reducing potential of polyols and the easiness with which any metal salt can react to form reducible complexes has been evaluated using the orbital molecular theory and the results were experimentally verified. The reduction limit of polyol and their extension using reaction promoting agents such as [OH-] ions is also explained. The reduction of cobalt is preceded by various reaction stages of complex/compound formation, which has been fully identified. Furthermore, the reducing form of cobalt has been identified as either cobalt alkoxide or cobalt hydroxide. The results confirmed that the complex forming reactions that take place prior to the formation of the precursor, which finally get reduced to metal, play a decisive role in determining the physical properties of the nanoparticles. The approach can be extended to reduce any metals or alloys using polyol process. - Graphical abstract: The role of polyol, precursor and reaction promoting agents in the synthesis of metal and alloy nanoparticles using polyol process has been investigated by analyzing the reaction steps involved in the synthesis of cobalt in Co ion-polyol-[OH-] system. Figure explains the entire reaction scheme in the formation of Co metal in ethylene glycol
[en] The angular distributions of cross sections and analyzing powers have been measured for the 58Fe(p, γ0)59Co reactions throughout the giant dipole resonance regions of 55,57,59Co. In addition, the 90degree yield curve has been measured for the 58Fe(p, γ0)59Co reaction for E/subp/ from 5.0 to 16.0 MeV in 100 keV steps. The data are analyzed to deduce the amplitudes and phases of the T matrix elements involved. The preferred solution indicates that the major change occurring in crossing the giant dipole resonance occurs in the relative phase between the d5/2 and g9/2 amplitudes. The implications of these results are discussed vis a vis the isospin splitting of the giant dipole resonance
[en] Effect of the presence of n-octanol in the extraction of traces of cobalt in HCl-TOA system was studied. In the extraction, both synergistic and antagonistic effects, depending on the volume of alcohol present, were observed. Extraction behaviour of the element was studied radiometrically using 57,58Co, produced by α- particle bombardment of cobalt, as radiotracer for the element. (author). 1 fig
[en] Chemical shift, differences of full width at half maximum (ΔFWHM) and full width at half maximum (FWHM) of Kα and Kβ1,3 x-ray emission lines were measured for the following Co compounds: Co, CoO, Co2O3, CoSO4.7H2O, Co(NO3)2.6H2O, CoCr2O4, Co(ClO4)2.6H2O, Co(C2H3O2), CoCl2.6H2O, CoCl2, CoF2, CoF2.4H2O and CoF3. The measurements were performed with wavelength-dispersive x-ray fluorescence spectrometry (WDXRF). It was found that the calculated results for Co compounds are strongly correlated with the oxidation state. At the same time, chemical shift for F compounds is generally more than that for Cl compounds. Larger chemical shifts and FWHM were also found for Kβ1,3 lines than Kα ones. It should be noted that the magnitude of chemical shifts increases with the increasing number of ligand atoms.
[en] Coordinations of poly(vinylene-arsine)s (1) towards transition metal ions were carried out to estimate the coordination ability of phenyl-substituted poly(vinylene-arsine) (1a) and methyl-substituted poly(vinylene-arsine) (1b). No 1a-Co complex was obtained upon addition of an acetone solution of 1a to an acetone solution of cobalt (II) chloride hexahydrate. On the other hand, 1b-Co complexes were obtained in the reactions at different cobalt salt-1b feed ratios. As in the usual case, the bivalent complexes of the reaction run corresponding to the feed ratio of 1:1 [CoCl2]/[repeating unit of 1b] oxidized readily in air to give very stable complexes of trivalent cobalt. On the other hand, the bivalent complexes of the reaction runs corresponding to the feed ratios of 1:4 and 1:10 both exhibited unusual stability against air oxidation owing to the higher concentration of 1b in the reaction mixture. Reactions of 1 and bis(2,2'-bipyridyl)ruthenium(II) dichloride also provided polymer complexes. In all the cases, 1b had higher coordination property than 1a due to its lower steric hindrance.
[en] The obstruction effect in the electrolyte diffusion of cobalt halides and in tracer diffusion of Co2+ ions in the presence of different supporting electrolytes at various concentrations was studied at 25 deg C using the zone diffusion technique. It was observed that obstruction effect expressed in terms of α increased with concentration and was higher for electrolyte diffusion than in tracer diffusion, however, for a given concentration it was found to descrease with increasing charge density of an anion. These observations are explained on the basis of competitive hydration between ions and agar molecules. (author) 8 refs.; 3 figs