For the purpose of obtaining characteristic X-ray patterns continuously from an arbitrary line element on the surface of a specimen having some local irregularities or changes, a camera of a new type has been designed. This camera is cylindrical, inner diameter 54 mm, outer 60 mm and length about 80 mm, and the primary X-ray beam is introduced parallel to the cylinder-axis but 10 mm apart from it. Both pinhole-system and cylindrical shield are fixed, while cylindrical cassette for photographic film, and cylinder cap for specimen are capable to rotate about the cylinder axis as ore body. The photographic film is inserted innerside of the cassette which is then covered by the cap. The specimen is fixed to the stem, of which the axis coincides with the rotating axis and which is faced to the cap. The shape of such specimen is of a truncated circular cone, and every part on the surface of the zone 10 mm apart from the axis is irradiated by the X-ray beam through the pinhole-system, fixed to the camera body. In order to protect the photographic film from undesirable blackening, both the pinhole-system and the specimen are covered by the cylindrical shield having a long slit, 1 mm in width and parallel to the axis. When the specimen and the photographic film are rotated during the exposure, the obtained patterns will take the form of several continuous lines.
These characteristics of this camera were confirmed by an experiment on partly hardened steel obtained using high frequency induction. In this way the present author has obtained patterns consisting of nearly straight lines having several diffuse and broken parts due to irregularities in the irradiated parts of the specimen.

抄録全体を表示

Various phase changes which occur in crystals of hexamethylbenzene and beryllium oxyacetate have been investigated by X-ray methods.
The crystal structure of hexamethylbenzene at high temperatures has been determined by single crystal oscillation method, (Cu Ka, λ=1.54 kX), in order to obtain some information about the anomalous volume change at high temperatures. It belongs to the orthorhombic system. The dimensions of the unit cell which contains four molecules of C₆ (CH₃) ₆ are a=9.06 kX, b=15.70 kX and c=7.52 kX at 155°C. The space group was found to be D²³_2h-Fmmm and the determined atomic parameters are shown in Table 2. Powder photographs were also taken at various temperatures, from which the change of the dimensions of the unit cell was deduced. The determined structure was discussed comparing with the structure at room temperatures which has been very accurately analyzed by Robertson and Brockway. The mechanism of the anomalous volume change was briefly discussed taking the thermal movements of the molecules into account.
The crystal structures of different modifications of beryllium oxyacetate have been investigated by X-ray methods, (Cu Ka) . An attempt has been made to derive the expression for the change of the Bragg and diffuse reflections of X-rays associated with the transition about 40°C, from the viewpoint of the thermal movements of the acetate groups. It was shown that the derived intensity expression could account for the characteristic feature of the observed X-ray scattering.
At 147°C the phase change of the first order occurs and when the temperature is raised above this point the substance assumes gradually the appearance of soft wax, though it melts sharply at 285°C. Powder photographs were taken at various temperatures. Most of the lines observed could be explained as due to a rhombohedral unit cell with dimensions a=9.72 kX. ar=54°20', containing one molecule in it. It will be noteworthy that this unit cell dimension is closely related to the cubic closest packing of spheres (rhombohedral lattice with ar=58°12') . This fact, combined with the observation that the X-ray intensity distribution in the powder photograph taken just below the melting point showed much resemblance to the liquid halo slightly above the melting point, suggests that the liquid state near the melting point may be considered to be cubic closest packing of molecules. Another modification of Be-oxyacetate can be obtained by sublimation, the crystal data of which are given.

抄録全体を表示

The general intensity equation for X-rays diffracted by a one-dimensionally disordered crystal i. e. I=N spur VF+ ^(N-1) Σ_n=1 (N-n) spur VFQⁿ+conj., which was derived for the“Reichweite”S=1, was found to be valid for any S-values by modifying somewhat the elements of the matrices. The mathematical content of SjS^*_j+n used by Wilson and Jagodzinski is equal to spur VFPⁿ for any S-values. Our antecedent method in which each layer form factor contains only one layer and the preceding (S-1) layers are used only to classify the layers belonging to the layer form factor into l (the number of combinations of (S-1) antecedents) groups, is found to be equivalent to the“whole S-layers” method used by Hendricks and Teller in which each layer form factor is taken over the whole S layers. We discussed the relation between the cases of S and (S-1) . A simple example is shown in case of r=2 and S=2 where r is the number of the kinds of layers.

抄録全体を表示