西暦2000年特別企画“20世紀のセラミックスを先導した論文”セラミックスの粒界拡散の研究

抄録

The 1950's and 60's were the decades when the field of traditional ceramics was brought under the light of analytical physical science. Especially sintering process of ceramics, which had been a matter of extreme complexity, was basically understood in terms of the atomistic diffusion process occurring in the bulk and/or on the interface of the coagulated body of the powder. On the extension a high temperature mechanical property, creep, was understood on a similar basis. The knowledge developed led to the discovery of highly dense sintered ceramics, now widely known as translucent ceramics.
The author started his career as a ceramist in late 60th when the understanding of sintering kinetics needed further elaboration. One of the apparent contradiction at the time was the fact that the faster diffusing species, i.e., cation in oxides was the rate determining one in the sintering process. There should be some process that enhances the diffusion process of oxygen. Gradually the importance of surface and grain boundary diffusion was paid attention. This review was written by the author in order to summarize many papers, appearing in those days and to establish the systematic view on those studies. He described how various processes involve the ionic diffusion and how grain boundary diffusion affects the processes based on the concept of the ambipolar diffusion. Starting from the accumulated knowledge in the metal and alkali halides as the simple model for ceramic materials, he related the scattered knowledge into a consolidated view that could be applied to ceramics.
In relation to this review he wrote additional reviews on “Diffusion Coefficient of Point Defects in Oxides” Yogyo-Kyokai-Shi, Vol. 87, No. 3, 36-42 (1979), and on “Kinetics of Various Mass Transport Processes on the Solid Surfaces, ” Oyo-Butsuri, Vol. 49, No. 6, 579-585 (1980) which in combination still form the basis of the current understanding of the field.