Ryozo Oyamada

Raman Spectra of the Fused PbCl2-KCl System

The Raman spectra of PbCl 2 -KCl system are investigated in the fused state. The spectrum of the fused PbCl 2 at 505°C exhibits two Raman lines at 120 cm -1 (depolarized) and 205 cm -1 (polarized). These lines can be assigned to Cl-Pb-Cl deformation mode (ν 4 , E 1 ) and Pb-Cl stretching mode (ν 1 , A 1 ) respectively, because we can expect that [PbCl 3 ] - ion-like local structure is predominant in the fused state considering the crystal structure of the pure PbCl 2 . The chemical shift of the 205 cm -1 line up to 230 cm -1 is observed with increasing KCl concentration, indicating that the chain structure of the [PbCl 3 ] - ions is broken into individual [PbCl 3 ] - ions due to the addition of KCl.

Characteristics of Glassy PbO-GeO2 Binary System by X-Ray Diffraction, Infrared Absorption, Dielectric Constant, and Intrinsic Absorption

Four characteristics of the glassy PbO-GeO 2 system were examined. X-ray diffraction pattern of the sample of 50 mol % PbO showed the maximum intensity at d -value 2.885 A which was in accordance with that of the compound PbO·GeO 2 (relative intensity 60 %). Infrared absorption band of the glassy GeO 2 at 11.5 µ, which would be assigned as ν 3 mode of tetrahedral GeO 4 unit, shifted toward longer wavelength side with increasing PbO content and the shift showed a plateau at 47-50 mol % PbO. Dielectric constant also kept neatly constant value at 47-50 mol % PbO The wavelengths corresponding to the intrinsic absorption coefficients per PbO mole fraction ( e. g. 70 cm -1 /m.f.) increase linearly with increasing PbO content, having the inflection point at 45 and 55 mol % PbO. The ionic character of the bond GeO 4 -Pb is discussed on the basis of the results.

Thermodynamische Betrachtung über die Bildung der Komplex-Ionen in des geschmolzenen ThCl4-NaCl Systems

The electromotive force and its temperature-dependence of fused salts of the ThCl 4 –NaCl system were measured with a Th(s)/ThCl 4 –NaCl(l)/Cl 2 (g) cell using highly purified ThCl 4 (ThCl 4 0.22–0.70 mole fraction, 600°–750°C). To discuss the formation and existence of complex ion in the melts, the equation of excess stability d\bar F 1 E /d(1- N 1 ) 2 , where N 1 is the mole fraction of ThCl 4 and \bar F 1 E the excess partial molar free energy of ThCl 4 , derived by Darken was adopted. Curves of the excess stability plotted against N 1 show a maximum at around N 1 =0.35 corresponding to the congruently melting compound Na 2 ThCl 6 . Meanwhile, plots of the equivalent conductivity and the isotherms, calculated from the previously reported values against N 1 revealed a large negative deviation from the additivity at N 1 =0.33(550°C–750°C). From these both results the existence of the anionic complex ion [ThCl 6 ] 2- in the fused state was inferred.

Polarization Power Parameter in Binary Fused Salt Systems

In order to show the limit of the congruently melting compound formation in binary fused salt systems introduction of a parameter is proposed in this paper. The parameter is defined by I 1 = n 1 P 1 /( n 1 P 1 + n 2 P 2 ) where P i and n i are the polarization power of cation ( P 1 > P 2 ) and the mole fraction of the i -th salt respectively. When the congruently melting compound is formed in the binary system of alkali chlorides the values of I 1 are found to fall into the range 0.5–0.95. Further, a linear relation is found between the equivalent conductivity of the binary fused salt system and the parameter I 1 . A discontinuous change in the slope is observed at the point where the congruently melting compound is formed.