Hahn first investigated the emanation method which used radioactive radon nuclides as tracers.
In the present work, the use of radioactive fission product rare gas for the emanation method in place of radon was proposed. The crystal structure change of γ-hematite to α-hematite was studied by this method and high temperature X-ray diffraction method was employed for the identification of the crystal.
The usefullness of this emanation method for the studies in the field of physical chemistry is also discussed.

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To get the sound heat element chiefly composed of MoSi ₂, at first we tested tap density, compressibility and compactibility of mixed powder itself of MoSi ₂, SiO₂, and Al₂O₃.
As the result of above powder tests, we could clear the compacting condition.
Furthermore, we measured electrical and mechanical properties of the cold-pressed specimens to get the best sintering condition in various gases.
Results were as follows :
(1) The tap density was 1.89g/cm³.
(2) The compactibility was proved successful without lubricant, its value being 3.2kg/mm².
(3) The optimum pressure of cold-pressing was 20kg/mm².
(4) Shrinkage percent was about 35-39%, with the sintering condition, at 1600-1650°C, in vacuum, argon gas and H₂ gas atmosphere.
(5) In vacuum, Ar gas and H₂ gas atmosphere, the optimum sintering temperature was 1600-1650°C. The density of the specimens sintered was 4.1-4.3g/cm³.
(6) Electrical resistance values of specimens sintered at 1600-1650°C in various atmo-spheres were in the range of 2.35-2.96×10^-4Ω-cm at room temperature.
Its values were higher than that of the specimens prepared with hot pressing.
(7) Electrical resistance values at 1400°C were 1.08-1.20×10^-3Ω-cm.
(8) Modulus of rupture at 800°C was 17.2-18.9kg/mm².

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Some properties such as room-temperature hardness, transverse-ru-pture strength, density and oxidation increase or microstructure of TiC-40 Ni⋅Cr⋅Mo cermet vacuum-sintered at 1280° and 1300°C for 1hr. were studied. Relation between the properties and the Ni⋅Cr⋅Mo alloy binder compositions in range of Ni>60, Cr>20 and Mo<20 wt.% was made clear. Results showed that the properties were continuously varied with increasing the content of Ni and Mo in alloy binder and the composition of binder for cermet having excellent properties was thought to be ranged 60-70% Ni, 20-25% Cr and 10-15% Mo approximately.

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Single domain ferromagnetic particles have a large coercive force. This character disappears at elevated temperature and the particles behave as if they are paramagnetic even at the temperature below the Curie point. The recent development in this field is reviewed.

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In order to obtain some information on the surface state of the reduced nickel powder in the case of the hydrogen adsorption, the change of magnetisation due to gas adsorption of the catalyst, the adsorption isotherms and heats of adsorption were measured before and after the sintering by the heat treatment at 500°C or the degassing at various temperatures. The change of magnetisation was determined by the low frequency a. c. permeameter method.
It is found that the distribution of nickel crystallites accommodated with the adsorbed gas is not homogeneous all over the surface of the catalyst and this distribution causes the occurrence of the first and the second stages in magnetisation isotherms. It seems that adsorption of the relatively finer particles on the surface occurs actively at the first stage, while that of the larger particles at the second stage. These phenomena can also be estimated by the modes of adsorption isotherm and adsorption heat.
Recently Selwood has reported that the magnetisation isotherm deviated from the straight line when the nickel was sintered. This finding is in line with my experimental result. My study indicates also that the transition point from the first to second stage in magnetisation isotherms shifts, when the catalyst was sintered, to smaller scale of abscissa, which represents the amount of adsorbed gas. The adsorption of the first stage in magnetisation isotherm was selectively inactivated by the heat treatment.
Diameter of nickel particles in the catalyst used in this study was determined by X-Ray diffraction pattern method, and these were 50-100A in diameter and in the super-para-magnetism range.

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Various thoery has been proposed for the properties of saturation magnetization of thin film, but the non variance with the decrease of film thickness was concluded from the recent experiment of Neugebauer.
The relation between the method of the preparation and the Anisotropic properties were discussed from experimental standpoints. The applications of thin film for the computers or high speed switching were also described.

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Characteristic properties of phase transition particles such as martensitic transformation, order-disorder transition in fine particles of Fe-Ni alloy were discussed in correlation with particle size. The mechanisms of γ-α phase transition of ferric oxide were also suggested from the electron diffraction studies of particles.
In genaral, diffusionless martensitic transformation, is suppresed with the decreasing of particle size. This effect is explained by the decrease of dislocarion density in fine particles. Meanwhile order-disorder transformation which accompanies diffusion is promoted by the excess vacancies introduced by the surface tension effect.
Lastly shape and size effects in the transformation of γ-ferric oxide were desccribed.

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