B_2O_3-Sb_2O_3系ガラスの性質と構造

概要

論文の詳細を見る
Following the previous report on the system of B2O3-GeO2, we studied some properties of B2O3-Sb2O3 glasses, as a glass-forming system, with the interest of Sb2O3 glass. In the first the valence of Sb in those glasses was examined. Sb2O3 reacts with the oxygen in air to give Sb2O4 at the temperature range from 400° to 500°C, as shown in Fig. 1. The melting temperature of this glass-system is about 700°C, and this temperature is in the stable range of Sb2O4. By the chemical analysis of the glasses dissolved in HCl, it is concluded that the valency of Sb is almost trivalent (Table 1). It was difficult to prepare the glasses from Sb2O4, instead of Sb2O3, without a long melting process, and the resulting glasses contained a negligible amount of Sbv (Table 2). Now it is assumed that the trivalent Sb ion is stable in B2O3-Sb2O3 glasses.We then studied the expansion coefficient of these glasses. As the results are shown in Fig. 3, the curve of the thermal expansion has the minimum at 20mol% of Sb2O3. In Fig. 4 this curve is compared with those of B2O3-SiO2 and B2O3-CeO2 systems. The deviation of these experimental curves from the straight lines jointing both their ends, represents the structurl decrease in the thermal expansion. As the deviations in the above three systems are nearly same, we consider, the reason of the decrease in the B2O3-Sb2O3 system is the same as in other systems. Namely, 4-coordinated Sb, which may be formed by an additional coordination, interferes with the thermal vibrations of B2O3.The temperature of the deformation, temperature of the transition, the density and the refractive index in this system are shown in Figs. 5, 7 and 8. It is noted that in the Sb2O3 rich range the increase of Sb2O3 lowers the transition temperature of glasses and on the contrary raises their liquidus temperature. Accordingly, it is assumed, the viscosity of Sb2O3 melt is low at the melting point and therefore the Sb2O3 glass may have a chain structure. The infrared spectra of the vitreous state and two crystalline states of Sb2O3 are shown in Fig. 9 and these spectra of B2O3-Sb2O3 glasses are shown in Fig. 10.From the data of DTA and of the infrared spectra, it is considered that the structure of glassy Sb2O3 resembles the valentinite (see Fig. 2 b). In the DTA curves of Sb2O3 glasses containing B2O3 from 0 to 30mol%, shown in Fig. 11, the first endothermic peak A, the following exothermic peak B and the last endothermic peak E indicate the glass-transition, the crystalization and the melting, respectively.The small endothermic peak D, which appears about the transition temperature of 570°C from the senarmontite to the valentinite, means this transition, because the same peak is found in the crystalline Sb2O3. The other small endothermic peak C seems to correspond to the reverse transition. It is confirmed by the change in the infrared spectra of Sb2O3 glass treated at 400°C (Fig. 12). Namely, the peak of the valentinite decrease with time and simultaneously the peak of the senarmontite increase progressively. We concluded that the glassy Sb2O3 devitrifies into the valentinite and then transforms into the senarmontite, the stable phase.
社団法人日本セラミックス協会の論文
1969-08-01

B_2O_3-Sb_2O_3系ガラスの性質と構造

スポンサーリンク

概要

著者

関連論文

スポンサーリンク