Shinjiro Katagiri

Some Applications of an Ultra-High Voltage Electron Microscope on Materials Science

Fundamental problems for application of a 3 MV-class electron microscope have been examined at 2 MV on various materials such as aluminum, copper, 18-8 type stainless steel and gold as follows: (a) The maximum observable thickness of these specimens at 2 MV is generally 12~13 times larger than those at 0.1 MV. And thus, it is expected that processes of various phenomena in most materials can be continuously observed as same as in bulk specimens by the electron microscopy. (b) The anomalous transmission of electrons clearly occurs at the symmetry position of 111 reflections at 2 MV even in aluminum. (c) Total amount of secondary defects due to electron irradiation damage strongly depends not only on the order of reflections but also on deviation from the Bragg condition. When the anomalous transmission at the symmetry position occurs, the amount of defects shows the maximum value at the symmetry position of reflections. (d) Utility of capsules are examined on determination of the liquid structure and oxidizing processes of aluminum.

Experimental Investigation of Chromatic Aberration in the Electron Microscope

Experimental results on the reduction of chromatic aberration in the magnetic electron microscope are described. It is proved that the chromatic field aberration can be completely compensated by a proper combination of two lenses with adequately designed pole pieces and the voltage stabilization tolerance is greatly improved. Micrographs with a resolution of about 5 mμ can be obtained even under a voltage fluctuation as large as ΔE/E=1.10−2.

Umwandlungs- und Ausscheidungsvorgänge in Metallen

Phase transformations in the solid state, and in particular those in metallic systems, form an interesting and important topic of scientific investigation. The study of phase transformations in metals and alloys is of importance to the metallurgist, for by controlling the character and extent of these transformations it is possible to produce materials of widely differing chemical and physical properties to meet specific technological requirements.

Application of the selected area diffraction from carbon extraction replicas for the study of carbide reactions and the inclusions in steel

In recent years the applications of the electron microscope to the study of carbides and non-metallic inclusions in steel, have greatly increased as the result of the development of the extraction replica technique. With extraction replicas the distribution and shape of carbides or non-metallic inclusions are clearly defined in the electron microscope. When several different types of particles are present at the same time diffraction patterns from individual particles can be obtained by means of the selected area diffraction technique and this method becomes particularly valuable if the microscope is adapted for operation at very high voltages. In preparing the extraction replica the time required to extract the particles onto the replica is short, therefore the risk of changes occurring is less than with particles extracted by the various electrolytic isolation techniques. The disadvantages of the extraction replicas are that there is a limit to the size and shape of the particles which can be extracted, whilst the treatments after extraction have to be more delicate than with electrolytically isolated residues. In view of the low accuracy obtainable in the determination of lattice parameters from electron diffraction patterns, it is better to use both the extraction replica-electron diffraction technique and the electrolytically isolated residue-X-ray diffraction methods together, as in this way accurate results may be obtained.

Linsen und Ablenksysteme

Die rechnerische Untersuchung eines elektronenoptischen Systems erfordert in der Regel so genaue Werte der Feldverteilung, wie sie nur mit modernen elektronischen Digitalmaschinen erhalten werden konnen. Die Erfahrung zeigt aber, das die Losung der Potentialgleichung nach dem Maschenverfahren mit programmgesteuerten universalen elektronischen Maschinen recht zeitraubend (Programmieren) und relativ kostspielig (lange Losungszeit) ist. Mussen laufend viele Felder berechnet werden, so lohnt es sich, eine relativ billige Spezialanlage zur Losung der Potentialgleichung zu bauen. Sie mus sich durch geringen Arbeitsaufwand bei der Einfuhrung der Ausgangsdaten und durch grose Genauigkeit auszeichnen und so die Vorteile eines Widerstandsnetzes und einer digitalen Rechenmaschine in sich vereinigen. Dies wird erzielt durch Serienschaltung eines Netzgerates, das die Potentialgleichung in erster Naherung lost, mit einer einfachen, spezialisierten Digitalmaschine, die den Approximationsfehler jener Losung reduziert.

Ein 300-kV-Elektronenmikroskop und einige Ergebnisse seiner Anwendung für verschiedene Forschungszwecke

Bevor die moderne Dunnschnittmikrotomie entwickelt wurde, war die mit sehr hohen Spannungen arbeitende Elektronenmikroskopie (vgl. Tab. 1) beinahe die einzige Methode zur Sichtbarmachung der sublichtmikroskopischen Struktur biologischer Praparate. Auser dieser Bedeutung fur die Elektronenmikroskopie hat die Anwendung sehr hoher Spannungen auch fur die Elektronenbeugung einen grosen Vorzug: man kann dadurch den Untergrund des Diagramms abschwachen und somit den Kontrast verbessern, wie Mollenstedt es fur den Fall der Durchstrahlung und Finch u. a. fur die Ruckstrahlung experimentell nachgewiesen haben.

The development of the lens system in the Hitachi electron microscope

Astigmatism was already mentioned in Ardenne’s famous book (1), but the astigmatism described therein was one of the Seidel’s aberrations of the third order and a field aberration. Axial astigmatism was more important, though it had not been well known at that time. We usually took underfocused micrographs, in which the astigmatic image defect was vague.