Indirect Displacement of Atoms in Solids by Knock-on Impurity Atoms

摘要

A cascade theory is developed in order to calculate the number of displaced atoms of a host material produced by knock-on impurity atoms. The theory is similar to the Kinchin-Pease cascade theory except that the atom which starts the cascade differs in mass from the other atoms with which it collides. The chief application of the theory is for evaluating the number of host displacements produced indirectly by knock-on impurities in radiation damage experiments. This is of interest as a sub-threshold effect and also as a possible source of error in determining the threshold for atomic displacement. The basic results are evaluated numerically for a wide range of cases which cover most situations of interest in radiation damage experiments. Numerical results are also given for the specific examples of carbon and rhodium impurities in platinum which show that in these cases the number of indirect displacements produced by knock-on impurities is negligible for most purposes. (Author)