Raman Spectra of Glassy PhO-GeO2 and PbO-B2O3 Systems

OYAMADA Ryozo, HAGIWARA Hisao

doi:10.2109/jcersj1950.86.992_151

Raman spectra of glassy PbO-GeO₂ and PbO-B₂O₃ systems were measured and analyzed. For pure glassy GeO₂, several bands were observed at 300-600 (peak position: 410), 760, 860 and 970cm^-1. The bands at 410, 760 and 860cm^-1 were assigned respectively to ν₄, ν₁ and ν₃ mode of the vibration of the tetrahedral GeO₄ which has T_d symmetry. For PbO-GeO₂ system a new band appeared at 750-850cm^-1 and it could be separated into two bands by the polarization. analysis. One of these new bands, the band of higher energy, corresponding to the band at 860cm^-1 of glassy GeO₂, was found to shift toward a lower wavenumber with increasing PbO content. The wavenumber of this band showed a nearly constant value in the neighbourhood of PbO⋅GeO₂ composition. The similar shift of another band of lower energy was also found. The fact might be related to the 6-folded coordination of Ge in tetragonal GeO₂ (rutile type). Such a trend of band shifting found in Raman spectra is similar to that of the infrared absorption spectra previously reported by the authors. For pure glassy B₂O₃, several bands were also observed at 450, 650, 806, 1260 and 1470cm^-1. The bands at 650, 806, 1260 and 1470cm^-1 were assigned respectively to ν₄′, ν₁′, ν₃′, and ν₃′ mode of the vibration of the triangular BO₃ which is D_3h symmetry. For PbO-B₂O₃ system, the bands at 1260 and 1470cm^-1 were united into a broad band and showed the shift toward a lower wavenumber with increasing PbO content, e.g. 1350cm^-1 for PbO 30mol% and 1245cm^-1 for PbO 70mol%, suggesting the effect of the interaction between Pb²⁺ ion and BO₃ group. A new band appeared at 1000-1150cm^-1, and could be assigned to ν₃ mode of BO₄ tetrahedral structure (T_d symmetry). The intensity of this band increased up to about PbO 50mol%, and then decreased with further increase of PbO. The fact might be related to the number of BO₄ structural units which are found in the system. Based on the above assignments, we estimated the force constants in GeO₄ and BO₃ structural units by GF matrix method. The values of f_r, f_φ and f_rφ for GeO₄ were 5.45, 0.55 and 0.13 (mdyn/Å) and for BO₃ were 6.13, 0.80 and 0.76 (mdyn/Å), respectively.

Raman Spectra of Glassy PhO-GeO<sub>2</sub> and PbO-B<sub>2</sub>O<sub>3</sub> Systems

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