ガラス状Na2O・SiO2-PbO・SiO2系の誘電率, 赤外吸収およびラマン効果
1974 年 82 巻 950 号 p. 558-563
詳細
1974 年 82 巻 950 号 p. 558-563
Dielectric constants and infrared and Raman spectra of Na2O⋅SiO2-PbO⋅SiO2 glassy system were measured with change in PbO content. The value of dielectric constant increased from 8.0 (Na2O⋅SiO2 glass) to 15.5 (PbO⋅SiO2 glass) with the increase in PbO content, but the value showed little variation in the ranges of 0-30mol% PbO and at about 35mol% PbO which corresponds to the composition of the congruently melting compound (C. M. C.), 2PbO⋅Na2O⋅3SiO2.
IR spectrum of Na2O⋅SiO2 glass showed two kinds of absorption bands at 9.5μ (1053cm-1) and 13.2μ (758cm-1) which correspond to the absorption bands of SiO2 glass at 9.1μ and 12.7μ, respectively. The band at 9.5μ shifted toward longer wavelength side with the increase in PbO content, but the shift of the band was not observed in the vicinity of C. M. C. composition.
Raman bands of Na2⋅SiO2 glass were observed at 530, 780cm-1, and 1095cm-1. The band at 1095cm-1 corresponds to that of SiO2 glass at 1060cm-1 and it would be assigned to the triply degenerated stretching vibration of SiO44--tetrahedral structure. This correspondence may be interpreted as follows: the strength of Si-O bond can be increased by releasing of oxygen edges of SiO44- network unit by O2- ions from Na2O, and then the wave number of SiO44- tetrahedral vibration shifts toward higher energy side, i.e. from 1060cm-1 to 1095cm-1. The band at 1095cm-1 also showed the chemical shift with the increase in PbO content and the trend of its shift is in agreement with that of IR band at 9.5μ.
From the fact that the value of D. C., the wavelength of IR band, and the wave number of Raman band keep approximately constant in the vicinity of C. M. C. composition, it can be said that the glass corresponding to C. M. C. holds a stable structure, though the arrangement of the unit (SiO44- etc.) of the network structure is in disorder.
It may be said from the polarization measurement of Raman spectra that the glassy state of the system holds the characteristic features of the liquid state fairly well.
