Li_2O-MgO-CaO-Al_2O_3-SiO_2-F系ガラスからの析出結晶について

概要

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Studies were carried out for the purpose of obtaining the information about the crystallization of the glasses having the compositions of Li2Ca(Mg3Al2) (Al2Si6)O22F2 and of added 0.5, 0.75, 1.0, 2.5mol excess Li2O to this composition. After the glasses were heat treated from 550°C to 1150°C for 1-92 hours, the precipitated crystals were examined by X-ray diffract method.The results obtained were summarized as follows:(1) β-quartz (ss) crystallized primarily in the glasses except the glass containing 2.5mol excess lithia, which could not expected to precipitate from the phase diagram of the system Li2O-Al2O3-SiO2 and MgO-Al2O3-SiO2.(2) β-quartz (ss) phases precipitated at comparatively lower temperature, except precipitated in the glass containning no excess lithia, were richer in SiO2 contents than precipitated at higher temperature.(3) Considering the Bealls equilibrium diagram at 1230°C in the system SiO2-LiAlO2-MgAl2O4, it was considered that the metastable region was present in the system SiO2-LiAlO2-MgAl2O4, where the metastable “Silica O” which was proposed by R. Roy in the system Li2O-Al2O3-SiO2 was existed with MgAl2O4 in the form of solid solution. In this study, the β-quartz (ss) precipitated at 900°C seemed to have only small fraction of MgAl2O4.
社団法人日本セラミックス協会の論文
1970-10-01