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  • Author or Editor: Y. Kato x
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Abstract  

The behavior of (UO2)2(OH) 2 2+ has been investigated in solid-liquid equilibria under 100%, 8%, 1%, 0.3% and 0.03% CO2 partial pressure as well as in undersaturated systems in equilibrium with air at 24±2°C in 0.1M NaClO4 solutions. From spectroscopic investigations by UV-Vis-and time-resolved laser-induced fluorescence (TRLF) spectroscopies, single component absorption and emission spectra are suggested for the (UO2)2 (OH) 2 2+ species. The lifetime 22 of the fluorescence emitting electronically excited state of (UO2)2(OH) 2 2+ was determined as 22 = 2.9 ± 0.9 s. The formation constant of (UO2)2(OH) 2 2+ was found to be log K22=–5.97 ± 0.06. Interpretation of the experimental data was also made assuming the species (UO2)2(OH) 2 2+ , but unsatisfactory results have been obtained.

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Abstract  

Luminescence lifetime of Eu(III) in polyacrylate and polymaleate complexes has been measured to evaluate the number of water molecules bound to the ion. The number of residual water molecules hydrated to Eu(III) in the polyacrylate and polymaleate complexes ranged from 3.5 to 4.5 when the supporting electrolyte concentration was 0.01. The residual hydration number decreased with the addition of supporting electrolyte. These results indicate that Eu(III) is surrounded by polymolecular ligands in these complexes.

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Abstract  

Laser-induced fluorescence spectroscopy was applied to obtaining hydration structure of Eu(III) complexes with synthetic polycarboxylates of poly(acrylic acid), poly(maleic acid), poly(methacrylic acid), and poly(a-hydroxyacrylic acid). Dependence of
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(the number of water molecules in the first coordination sphere of Eu(III) ion) on pH and supporting electrolyte concentration was obtained for these complexes. The spectroscopic results show that Eu(III) is surrounded by the “cage” of polycarboxylate ligands. The pH-induced transition in conformation of poly(methacrylic acid) ligand was clearly observed in the
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plot vs. pH.
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Abstract  

We have focused on the poly(ethylene glycol) (PEG)-borate ester as a new type plasticizer for solid polymer electrolyte for lithium ion secondary battery. Adding the PEG-borate ester into the electrolyte shows the increase in the ionic conductivity of the polymer electrolyte. By measuring the glass-transition temperature of the polymer electrolytes with DSC, it is found that the increase in ionic conductivity of the polymer electrolyte is due to the increase in ionic mobility. By investigating the temperature dependence of the ionic conductivity of the polymer electrolytes using William-Landel-Ferry type equation, we considered that the PEG-borate ester does not have any influence for dissociation of Li-salt.

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Abstract  

The complex phase transitions involving dielectricity and magnetism on distorted triangular lattice antiferromagnets, "KNiCl3-family" crystals, which have the crystal structures derived from the prototype CsNiCl3, were studied through the heat capacity measurements. These crystals are classified into characteristic three groups from the viewpoint of magnetic and structural properties clarified so far. The results of the dielectric constant measurement as a function of temperature are also presented in detail. The present calorimetric study reveaed that the structural successive phase transitions rather than the magnetic transitions in these crystals are recognized more distinctly as the presence of specific heat anomalies at the respective phase transition points.

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