Several growth experiments were performed to clearify the process of inclusion of small carbon particle which is often observed in the crystals grown by Lely's sublimation procedure. In this study, special attention was called to the effect of the cavity wall, temperature of recrystallization and the initial increasing rate of temperature. The features of inclusion were observed with the technique of dark field photomicrography. The crystals obtained in these experiments are often showed certain orientation and zonal structure of the concentration of these inclusion. From the relation between observed results and the condition of growth, it is concluded that the most important factor related to this phenomenon is the composition of vapour phase in growth cavity shifted to carbon side than the equilibrium condition. The orientation and zonal structure of inclusion are explained by microscopic temperature distribution and fluctuation of temperature in a crystal.
Though the results obtained are not sufficient yet, it is shown that the great improvement is performed when recystallize at low temperature; e.g. 2300°C using the thin graphite cylinder by Kroko as a cavity wall and the proper, not so high, initial increasing rate of temperature. The background of these action are discussed in this paper.
Another experiments were also tried to prevent positively the inclusion by effusing silicon vapour from graphite clucible coupled with Lely's growth cavity. These trials, however, were always unsuccessful because the graphite clucible containing molten silicon was broken down by the reaction with silicon.
It is suggested, based on these results, that the better results would be obtained to recrystallize under high atomospheric pressure and to take care of the losses of silicon vapour from the growth cavity.

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In order to obtain the knowledge of the bond energy relations in alkali silicate glasses and crystals, a series of thermochemical calculations was carried out.
The experimental data used for the calculation were the previously reported values of the heat of solution of silicates in high alkali region and the present values in low alkali region. From the reexamination of the data the previous discussion on the Si-O-Si bond strength was partly amended. On the basis of the present results the heats of formation of the glasses and crystals were calculated, and the equations for calculating the O-R bond energy were derived from the heats of formation and other thermochemical data.
The calculated values of O-R bond energy of glasses and crystals in the systems Li₂O-SiO₂, Na₂O-SiO₂ and K₂O-SiO₂ were listed and discussed in comparison with the coulombic energies. The Si-O-R and Si-O bond energies were also calculated from the total energy and the O-R bond energy by applying the thermochemical cycle. It was shown that the differences between the bond energies of Si-O-Si and of Si-O were generally small.

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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 Beall's 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.

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Brown aluminous abrasive grains #36 to #120 in size, of corundum containing Ti³⁺, were heated at fixed temperatures between 1200° and 1400°C for various time periods and then the lattice spacing, d_0·4·10 of corundum was measured. The following results were obtained.
1) Differences in d_0·4·10 between abrasive corundum and pure alumina corundum before heating were between 0.00048 and 0.00070Å.
2) The relation between heating time, t, and exolution ratio of the titanium, X, could be approximately expressed by the following equation:
X=1-6/π^2∞Σ_n=1 1/n²exp(-n²π²Kt)
where K is a constant depending on heating temperature and natures of abrasive grains.
3) Linear relationship existed between log K and the reciprocal of heating temperature in °K. Apparent activation energies were between 92 and 117kcal/mol.
4) Grain size dependency of the exolution rate was investigated by heating at 1350°C. K was approximately proportional to D^-1.3. D is grain diameter.

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Sapphire is the single crystal of alumina, having high corrosion resistance, high thermal resistance, special hardness, superior electrical properties and transmittivity.
Sapphire has been utilized for nozzle, bearing, window for microwave tube and also in laser field.
This substance-to-metal sealing is very difficult. The author sealed the sapphire to Ti metal by reactive alloying method utilizing Ti-Ni for requirements on utilizing sapphire and expanding the sapphire's use, and author observed and examined the sealed part by the photomicroscope, the electron microscope and X-ray microanalyzer.
These results are as follows:
(1) By reactive alloying method utilizing Ti-Ni, it is possible to seal in vacuum-tight the sapphire to Ti metal.
(2) Sealing surface which is flat and slightly rough, is good to obtain the vacuum tightness and high seal strength.
(3) In the sealed part of the sapphire to Ti metal, five boundary layers are observed. These layers have characteristic distributions of concentration of Al, O, Ti and Ni elements.
In particular, Ti is absorbed selectively at the interface between sapphire and metal, and Ti concentration is higher than Ni concentration at this place.
(4) At the interface between sapphire and metal, the layer of solid solution or compound of Ti-Al-O system is formed mainly, and the bond between this substance and metal seems to be completed.

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