A spinel phase which contains fluorine as an anion in the formula, (Li_64/11, Al_192/11, Vac_8/11) (F_64/11, O_288/11), has been obtained, where Vac means vacancies on cation sites. Hydrothermal treatments of mixture of LiF and Al₂O₃⋅3H₂O at the molar ratio of 40:60 at the temperature above 450°C under the water vapor pressure of 400-800 atm. give the spinel phase without any contamination by other phases. This method is better than that in air in order to beep fluorine in the spinel structure. A part of fluorine is substituted by oxygen on heating the spinel in air.
The cation deficient spinel with the composition of (Li_64/11, Al_192/11, Vac_8/11) (F_64/11, O_288/11) in the unit cell is of the cubic cell dimension a=7.926 Å and belongs to the space group of Fd3m, where Vac means cation vacancies. The specific gravity was measured as 3.43, while the theoretical value was 3.48.

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Discussions are made on the mechanisms of stress build-up in glass, that is, the contraction of glass network caused by ultra-violet light with special regards to alkali borate glass. The processes of the contraction or configuration change of the network are presumed from some fundamentals, namely; photochemical effects of ultra-violet light on materials, characteristics of chemical bonds in the network of borate glasses and many experimental results obtained in the previous studies. Assumed processes are as follows:
1) Translation of alkali ions caused by elongation of excited >B-O^- bonds
2) Rotation of BO₃ or BO₄ groups caused by twisting or change of bond angle of excited B-O-B bonds,
3) Formation of new bonds between non-bridg-ing oxygen ion in a BO₃ triangle and B ion in the neighbouring BO₃ triangle: This reaction is initiated by elongation of the excited >B-O^- bond and as a result, transition of BO₃ group into BO₄ tetrahedron occurs.
4) Formation of new bonds similar to that described in 3., but caused by charge transfer in a >B-O^- unit,
5) Formation of new bonds similar to that described in 3., but caused by photoinization of non-bridging oxygen ions.
Special attention is paid on the double bond character of >B-O- or >B-O^- bonds, unstability of the network of glass after ultra-violet irradiation and stabilization effect of alkali ions which incorporate in the processes.
Those assumed processes are well accord to the experimental results.
Similarities between the photochemical processes in glass and in organic materials and differences between the photochemical reaction in solid glass and the glassf orming reactions in borate melt are mentioned.
At conclusion, the authours of the present paper intend to establish tae theory on the phenomenon by ascertaining or modifying the presumption with further experiments.

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Generally, opacity of leadless porcelain enamel for aluminum alloys is inferior than lead-bearing porcelain enamel. Previously, enamel of the system PbO-SiO₂-V₂O₅ was studied and good opaque enamels could be made by deposition of lead silico-vanadate having a vanadinite structure in it. The present investigation was undertaken to establish a good opaque leadless enamel of the system BaO-CdO-SiO₂-V₂O₅, in which some vanadate crystalline phases would be depositted.
The results obtained are summerized as follows:
(1) Crystalline phases depositted in these enamels were α-K₂SO₄ type hexagonal xBa₂SiO₄-(1-x)NaBaVO₄ solid solution and monoclinic 8BaO⋅R₂O⋅3V₂O₅ crystal (R represents alkali ion). The other minor crystalline phases in these enamels were tetragonal BaTiSiO₅, perovskite type cubic SrTiO₃ and ilmenite type unknown hexagonal crystal.
(2) The amount of BaO and CdO in frit was governing factor determining which phase would be crystallized in enamel. From the frits containing both BaO and CdO, α-K₂SO₄ type crystalline phase was depositted, but another frits contained only BaO, 8BaO⋅R₂O⋅3V₂O₅ phase was depositted. It was assumed that this phenomena attributed to viscosity-depression of frit by addition of CdO.
(3) From many synthetic experiments with substitution of each cation in α-K₂SO₄ type R⁺Ba(R⁵⁺O₄) compound, it is concluded that the most stable phase in which the cations are exactly fit this structure is NaBa(PO₄).
(4) Chemical durability, particularly acid resistance, of these enamels were inferior to other enamels, e.g. lead silico-vanadate enamels. It was assumed that besides the kind of crystal depositted, diffusion and segregation of a certain ions as alkalis was a factor determining the chemical durability of the enamel.
(5) Good opaque enamels were established by using a higher content of V₂O₅ in frit. Colored enamels were made by addition of Co₂O₃ or CuO in frits. But external appearance of these enamels were, generally, not very satisfactory.
(6) As a result of displacement of BaO by CdO in frit, an increase of thermal expansion, a lowering of softening point and an improvement of chemical durability were observed, but enamels slightly tinged with red were obtained.

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SbSI is a ferroelectric material with the c-axis as ferroelectric axis and the most strongly piezoelectric material known. The permittivity of SbSI single crystal of the c-direction is about 25000 whereas that of the a-direction is 25. Till now, due to the difficulties in obtaining large crystal, it is very hard to use this material for practical applications. Specimens used in piezoelectric measurement reported by RCA group consisted of thin discs cut from bundles of SbSI needles embedded in Araldite.
SbSI single crystal tends to grow in form of thin needles along the c-axis. In this report, the hot-pressing technique was applied to the powder of SbSI crystals in order to obtain the hard polycrystalline ingot having the oriented c-axis and systematic experiments were carried out on the effects of the hot-pressing temperature (T_m), the pressure (P_h) and the time (t_p) influencing upon the orientation of the c-axis in the hot-pressed specimens.
The results obtained are summarized as follows.
(1) When P_h was applied to the z-direction of the press mould, the c-axis of SbSI microcrystals were oriented in the x-y plane of the press mould. In this case, the permittivity of the x-direction (ε_x) is 1400 at the Curie point whereas that of the z-direction (ε_z) is 160.
(2) When the pre-forming pressure to the y-direction and the hot-pressing pressure to the z-direction were applied, the c-axis were oriented to the x-direction of the pressed specimens. In this case, the permittivity of x, y, and z-directions at the Curie point are 3000, 1000, and 240 respectively.
(3) The orientation of the c-axis in the hot-pressed specimens was also ascertained by the observation of the etched surface by mean of a microscope.
(4) The piezoelectric constants such as k₃₃, s₃₃^E, s₃₃^D, d₃₃, f_R⋅t were measured for the hot-pressed specimens prepared under a condition of T_m=370°C, P_h=250kg/cm², and t_p=1hr. This specimens showed an electromechanical coupling coefficient k₃₃ of 35%.
(5) The Curie temperature of the hot-pressed SbSI of 30°C is higher by 10°C than that of the SbSI single crystal If the phase transition of SbSI is order-disorder type, it may be considered that the rise of the Curie point by the hot-pressing is the effect of the residual strain generated while hot-pressing.

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