日本金属学会誌

J. Japan Inst. Metals, Vol. 19, No. 10 (1955),
pp. 567-571

Study on the Sintering of Germanium

Takashi Kimura


Abstract:

The most important problem in the study of a transistor is to get higher purity germanium. In this experiment powder-metallurgic method has been applied for that purpose. However, this trial was a failure, because germanium is found to be very difficult to sinter. There remained much voids in the specimens even when they were sintered just below their melting point. On the other hand G.A. Geach reported in his general study the ``Theory of Sintering'' in Progress in Metal Physics 4 (1953) that germanium did not sinter at 850° as the covalent bond metal is very difficult to diffuse. From our study, we felt a doubt about his explanation. In sintering there did not appear any shrinkage really at that temperature, but the cleavage of the sample showed a shell-like face which is characteristic of germanium, and this revealed a cohestion of particles in the specimen. ``Shrinkage'' which is auseful measure of sintering could not be found even at α=0.9. The powder used was n-type germanium as it was melted, but, during the process of sintering there appeared no typical change which would indicate a characteristic temperature of sintering, and no n-type sample could be obtained in the case of a sintered sample. However, the electrical resistivity of the a sintered samples began to fall critically at 600° which temperature corresponds to the other characteristic temperature of plasticity, and the value of resistivity was much higher than in a bulk germanium. By metallographical method, the behavior of the voids could be clearly understood. Adhesion phenomena appeared from 700°, the particle assembly began to enlarge and at last voids remained in the specimens near the melting point. There appeared also spherodizing phenomena, and the large voids increased their volume by annexing the small ones. Many such strange phenomena were found in the case of germanium during sintering as compared with other metals.


(Received 1955/5/13)

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