真空還元にもとづくルチル（TiO<SUB>2</SUB>）中の点欠陥の拡散に対する加熱中汚染の影響について

Abstract

The single crystal rutile in the form of slices was reduced in vacuum. The reduction was performed in three kinds of vacuum atmospheres, (A) vacuum by a diffusion pump without traps, (B) vacuum by a diffusion pump with liquid nitrogen traps and (C) vacuum by an ion pump. The process of reduction is considered to represent the process of diffusion of point defects induced by reduction. The diffusion coefficients of point defects in the reduced rutile were determined by the theory of the diffusion in a plane sheet with an equal surface concentration and the uniform initial distribution of solute in the sheet. These coefficients obtained in vacuum by the diffusion pump varied with the reduction time and this tendency was more remarkable in the case of the diffusion pump without traps. But the diffusion coefficients obtained in vacuum by the use of the ion pump were nearly constant at any reduction temperature independent of the reduction time except the beginning. It seems that these differences are due to the contamination by the diffusion pump. It becomes evident that specimens reduced with the diffusion pump are influenced by contamination by the diffusion pump oil. For the investigation of the reduced rutile, therefore, the ion pump should be used instead of the diffusion pump. By using the ion pump, the diffusion equation of point defects in the reduced rutile can be expressed as(This article is not displayable. Please see full text pdf.) This activation energy is very close in value to that of the oxygen vacancy in rutile.