硝子状より金属化したセレンについて

Abstract

In connection with the metallic selenium converted from the vitreous state by reheating at various temperatures,the examination was carried out by utilizing X-rays,as well by taking the microscopic structures and the differential thermal curves. The results thus obtained are summarized as follows:1. As can be seen in Table 2, the selenium metallized by reheating at a temperature 80°∼200°, was found to contain besides the hexagonal one an unknown variety, which had not been detected up to the present time. This variety shows the same crystal structure as the monoclinic selenium deposited at 20∼60° from CS2 solution of the vitreous selenium, as may be seen in Table 3, which it has hitherto been considered that is cannot be produced by the metallization from the vitreous state.2. The quantity of the monoclinic selenium co-existing with the hexagonal one was found to be much greater in the metallized specimens heated at the temperature nearest to the melting point than in those metallized at a lower temperature. It was also conceivable from some results of the thermal analysis reproduced in Fig. 2, the transition from the hexagonal selenium into the monoclinic one near the melting point might occur, though not so distinctly.3. The specimens of the vitreous and red amorphous selenium both tend to crystallize imperfectly at the room temperature after 2 or 3 weeks. Because in the diffraction patterns of X-rays taken with these specimens, (10\={1}0) line corresponding to the hexagonal crystal was only perceptible, accompanied by a very faint line corresponding to the monoclinic one specially in the case of the vitreous selenium, and the other lines reflected by these two kinds of crystals were hardly detectable. Furthermore, it must be postscribed that the aforesaid (10\={1}0) line reflected by the hexagonal forms was observed to be strengthened by heating at a temperature 50° for 48 hours, while the line coming to appear from the monoclinic one remain unaltered. This shows that the metallization of the vitreous selenium at the lower temperature is mainly due to the transformation into the hexagonal selenium and not into the monoclinic one.4. It was found by the microscopic examination that the nuclei grew in the course of the metallization of seleniun to a set of textures, each radiating out from a nucleus into the vitreous region as shown in Photos. 1, 2, 3 and 4. By the furtherance of the procedure of heating, this texture was observed to be broken down minutely as may be seen in Photos. 5, 6 and 7, and then augmentation of each grain took place, the more remarkably the more the temperature was high, by the recrystallization phenomenon as shown in Photo. 8.