The negatron decay of ¹⁵⁷Eu was investigated with a conventional scintillation spectrometer. Intense gamma rays were observed at energies of 65, 370, 410 and 620 kev with a half life of 15h. Five weaker gamma rays were also found. Beta-ray groups with maximum energies of 1.35, 1.28, 0.90, 0.87, 0.66 and 0.53 Mev were found from single and coincidence measusements. Decay energy is determined to be 1.35 Mev. From the analyses with the aid of Nilsson model, a tentative decay scheme of ¹⁵⁷Eu is proposed.

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The hyperfine structure (hfs) of the spectrum of ytterbium was studied, using separated isotopes 171 and 173 as well as natural ytterbium. The nuclear moment ratio μ(171)⁄μ(173)=−0.7248±0.0008 was obtained; and from the known value of μ(171) the value μ(173)=−0.6802±0.0010 nm was obtained. The nuclear quadrupole moment of Yb¹⁷³ deduced from the levels 6s6p ³P₁ and ³P₂ is 3.1±0.2 b without shielding correction. The method of the calculation is discussed.

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The boron diffusion into silicon has been investigated over a temperature range from 1100°C to 1300°C in a condition of constant source. True concentration profiles of boron diffusion layers were obtained by means of activation analysis by proton irradiations and conductivity measurements in order to understand the anomaly of apparent diffusion coefficient calculated from usual p-n junction method. In the case of low surface concentration less than 6×10¹⁹/cc, the boron distributions are represented as error function complement, whereas at higher surface concentrations they show more convex distribution. The fast diffusivity in the high concentration region is attributed to the enhanced diffusion by induced lattice strain.

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The properties of dislocation wall consisting of an infinite number of two kinds of edge dislocations whose Burgers vectors are at right angles to each other, are investigated on the basis of isotropic elasticity theory. The stress field in the region apart from the wall is divided by the planes perpendicular to the wall into unequally spaced bands, which are composed of positive and negative regions of the stress field. On the other hand, dilatational strain field is divided into equally spaced bands. It is concluded that the pinned compound tilt dislocation wall is a more effective barrier in comparison with the simple tilt wall for the penetration of dislocations.

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Numerical calculations are made on the lattice vibration of the cubic BaTiO₃, where the interactions among the constituent ions are taken into account. With some “enhancement factors” introduced for the dipole interaction, which have hitherto been overlooked, the reciprocity law is made consistent with regard to the respective interactions among the ions. It is found that, among the three modes which are optically active, the lowest mode is the bending type and becomes rapidly unstable for the increasing dipole interaction.

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The electrical resistivities, Hall coefficients and thermoelectric powers of undoped, Si-doped and Mn-modified CrSi₂ crystals have been measured over the temperature range from 90°K to 1100°K. The undoped crystal is a p-type semiconductor with the hole concentration of about 4×10²⁰/cm³. The hole concentration is decreased by doping silicon or manganese. Manganese atoms act as donors. Specimens heavily doped with manganese are n-type at low temperatures and change to p-type at high temperatures. Analysis of the experimental results leads to the following conclusions: (1) the forbidden energy gap=0.35 eV, (2) the ratio of the electron mobility to the hole mobility\simeq0.01 and (3) the density of state effective mass of electrons\simeq7 m₀ and that of holes\simeq5 m₀. Assuming that the effective masses and the mobility ratio do not vary with temperature, the temperature dependence of the thermoelectric powers of the undoped and doped crystals can be explained satisfactorily.

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A calculation is performed in order to treat the problem of the relative stability of ferroelectric and antiferroelectric arrangements of constituent atoms in the AO₃-type crystal such as WO₃, where the electronic polarizabilities of negative and positive ions are regarded as the variable parameters. It is disclosed that the stability of each arrangement depends in a delicate manner upon the electronic polarizabilities of the constituent ions, and that, with a reasonable choice of these polarizabilities, the ferroelectricity and antiferroelectricity of tungsten trioxide can be explained. It is also found that a sort of “ferrielectric” state can be realized for some values of the polarizabilities of the ions in the AO₃-type crystal.

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The anisotropy Ku at −183°C in iron-deficient Ni-Co ferrites cooled down from room temperature in magnetic field is observed. It increases rapidly with decreasing contents of Fe₂O₃ and seems to attain a saturation value at a certain value of Fe₂O₃ contents. It also increases approximately in proportion to Co concentration. The activation energy for this process is about 0.25 to 0.4 eV. This anisotropy has been explained in terms of the preferential occupation of Co³⁺ ions in the four kinds of 16d sites arising from electron migration between Co²⁺ and Co³⁺ ions. The anisotropy Ku is not observed in iron deficient Mg-, Mn-, and Cu- ferrites containing a small amount of Co.

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The resonance line broadening due to carrier-carrier interaction in cyclotron resonance spectrum in pure germanium was investigated by increasing the density of photo-generated carriers up to 10¹⁴ cm⁻³. Measuring temperature ranged from 1.6°K to 15°K. The carrier density was estimated by combining the plasma shift of resonance line with the area under the absorption curve. While at high temperature the increment of the line width is approximately proportional to the carrier density, it is proportional to the square root of the carrier density at low temperature. It was found that the behavior at high density was well interpreted by the term of the scattering process by another carrier obeying the Brooks-Herring formula with the use of reduced mass of two interacting carriers. On the other hand, the broadening at low temperature for low density is rather inhomogeneous in the sense that the cyclotron frequency is randomly modulated by the Coulomb field due to another carrier.

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By using the vector picture introduced previously, it is shown that disordered diatomic chains with sufficiently large mass-ratio have very strong tendency to have eigenfrequencies which are close to those of localized modes produced by several types of islands containing light atoms imbedded in a regular lattice composed of heavy atoms. This explains why the vibrational frequency spectra of disordered chains have in general very complicated structures with many well-defined peaks.

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Elastic constants of binary alloys, Ni-Fe and Ni-Cu, of their wide composition ranges having f.c.c. structure, were measured by means of a composite oscillator method in the frequency range from 1 to 5 Mc/s at room temperature. Elastic constants of Ni-Fe alloys vary quadratically as their compositions, while those of Ni-Cu vary linearly. These results can be interpreted in terms of the central and pair-like interactions between atoms of the alloys.

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The velocity and attenuation of ultrasonic waves at magnetic fields, sufficiently high to produce magnetic saturation in nickel and Mn-ferrite, have been measured as a function of orientation, intensity of magnetic field, and ultrasonic frequency at room temperature. In the case of nickel, the change in ultrasonic velocity was inversely proporational to the applied magnetic field in the range from 5 to 20 kG; the ultrasonic attenuation coefficient also changed and showed a frequency dependence of the relaxation type \fracω⁄ω₀1+ω²⁄ω₀² in the range from 5 to 65 Mc/s. In the case of Mn-ferrite, it was found that the magnitude of the changes in ultrasonic velocity was almost the same as that in the case of nickel, but no attenuation change was observed within experimental error. All the observations can be explained by the theory based upon magneto-elastic coupling and eddy current loss.

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The experiments of cyclotron resonance were carried out for the charge carriers in cadmium sulfide single crystals. The samples were selected from cleaved parts of high pure grade A and ultra high pure grade CdS crystals of Eagle Picher Co. The absorption corresponding to effective masses m^*=0.17 m and m^*=0.81 m was observed by use of 6 mm wavelength microwaves at 1.7°K. The light mass may correspond to free electron and the heavy one to hole. When the sample was not in contact with liquid helium, the absorption peak became broader due to the increase of lattice temperature, and at 9°K, the absorption decreased gradually with increasing magnetic field. These results mean that ωτ becomes smaller than unity with increasing temperature.

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New ferroelectric tungsten bronze type solid solutions were found with compositions 0.2≤x≤0.4 for Sm and La compounds, and x=0.25 for Y compound. The maximum dielectric constants were observed at about x=0.2 for each system, and corresponding Curie points were 278°C, 189°C and 10°C for Y, Sm and La compounds respectively. The hysteresis loops were observed below the respective transition temperatures. In R₂O₃-BaO-Nb₂O₅ system, single phase region of tungsten bronze type structure is determined. End member of the system, RNb₃O₉ for Sm, or Y system, was mixture of RNbO₄ and Nb₂O₅, but for La system a new compound LaNb₃O₉ was identified.

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By electron diffraction and X-ray diffraction, the following facts are found. 1) A new tetragonal structure (a=13.5 Å and c=4.14 Å) exists below a transformation point at about −168°C. 2) This structure changes (at −168°C) to the cubic structure which has already been known, after changing into a transient tetragonal structure (a′=1⁄2·a and c′=c). 3) The cubic structure shows a volume change of about 2% at a higher transformation point at −147°C.
The arrangement of sulphur atoms in the transient tetragonal form is determined from Patterson synthesis and trial and error method on the basis of the data given by electron diffraction. The structure is composed of double zigzag chains of sulphur atoms along the c-axis. The stable tetragonal structure of the lowest temperature phase is considered to be a super-structure of the intermediate form. The relations between these lattice transformations and changes of physical quantities are discussed.

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Twin walls in NiO single crystals were studied with Lambot X ray diffraction technique. The amounts of tilt at some twin walls were in good agreement with the value expected theoretically in a simple twin structure. But they were in other cases quite different. It is concluded that twin walls are sometimes connected with crystalline lattice irregularities. Tilts of about 1′ are observed as a fine structure of the diffraction pattern, which suggests the presence of magnetostriction of about 10⁻⁴ in NiO. Dislocation density of as-cleaved and annealed crystals were estimated to be 10⁸⁻⁹ and less than 10⁶ cm⁻² respectively.

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Diffuse streak patterns from single crystals which have become to be noticed very recently in electron diffraction are identified with the “non-radial” streak patterns in X-ray diffraction and their description in terms of parallel wall distribution of intensity weight along low index reciprocal net planes is discussed. Evidences for the description in electron diffraction patterns from silicon, germanium, aluminium, gold, iron, sodium and potassium chlorides and barium titanate are illustrated. An assumption of linear chain scatterers consisting of a small number of nearest neighbour atoms shifted from their regular positions is shown to be able to reproduce the characteristic features of the streak patterns from diamond structure and simple face centred cubic structure. Applicability of similar assumptions to the other cases is suggested.

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The mechanism of trigger action in a double electrode spark gap was investigated, clarifying the role of a plasma-jet ejected from the nozzle of the double electrode. Time lag characteristics were measured under several different voltages. Form and growth of a plasma-jet were observed with a suitable arrangement of a lens and a photo cell.
The results show that the trigger mechanism may be assumed as follows: (1) A plasma-jet, ejected with a trigger spark, behaves itself like a protruding conductive stick. (2) Electric field strength in the gap is increased with growth of the jet. (3) A main spark is initiated in the space between the jet-front and the anti-electrode. (4) The critical distance between the jet-front and the anti-electrode is dependent on the voltage applied to the anti-electrode, and independent of gap length. Ions transported by the plasma-jet help to initiate the main spark.
From these assumptions, sparking voltage and time lag characteristics, fluctuation of time lags, and effect of various factors, are explained.

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The unified theory developed by Kihara and the present author is applied to oscillatory phenomena. As an example the response of two-component plasma to high-frequency electric fields is investigated. The increment of the plasma frequency and damping coefficient of the plasma oscillation are obtained.

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The excitation transfers through collision between hydrogen atoms and between other simple identical atoms are considered theoretically by an impact parameter method. A rotating atom approximation and a fixed atom approximation (concerned with the direction of electronic polarization) are applied to the problem. The cross-section for the transfer of the excitation (2p ²P) of a hydrogen atom with thermal velocity (kinetic energy of 0.025 ev) to the other hydrogen atom in the ground state is estimated to be 3065 Ų with the rotating atom approximation and 680 Ų with the fixed atom approximation. In the case of helium atoms, the cross-section for the transfer of the excitation (2p ¹P) is also estimated to be 606.7 Ų with thermal velocity.

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Boundary layer equations for the flow of Reiner-Rivlin fluids have been obtained. These have been integrated by using K. Pohlhausen’s method in the inlet region of a channel and analytical expressions for the inlet length, the boundary layer thickness and the pressure drop have been obtained. Pressure drop has also been obtained from kinetic energy loss in the inlet length.

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The solution is obtained for the steady rotation of a magnetized sphere in an incompressible viscous conducting fluid. The rotation is supposed to be slow enough to justify the neglect of inertia terms. An account has been taken of the electric field induced by the motion, and expressions upto second order perturbations in the velocity field have been obtained.

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The problems of circular and elliptic inclusions tending to undergo spontaneous dimensional changes in infinite isotropic elastic continuous unstressed or stressed material, the matrix, have been considered by the authors in previous papers. In these problems the elastic properties of the inclusion were taken to be different from those of the matrix. In this paper the exact analytical solution to such a problem when elliptic inclusion and matrix are of different orthotropic materials has been obtained. The solution has been obtained by the applications of the minimum strain energy principle first suggested by one of the authors (R.D.B.) coupled with a semi-inverse method and complex variable technique. Continuity of normal and shearing stresses at the interface is demonstrated, providing a useful check on the analysis.

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P. 1730   Fig. 4, 1⁄\sqrtC indicating the dotted curve should be 1⁄\sqrtc. Fig. 6, M(4.2)/2 and M(300) indicating the upper and the lower magnetization curves respectively should be added.
P. 1732   Eq. (4),   g(n)=₁₂C_u c¹²⁻ⁿ(1−c)ⁿ
should be   g(n)=₁₂C_n c¹²⁻ⁿ(1−c)ⁿ.
P. 1734   Reference (3), the number of page, 278 should be added.

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