Impurity and Decay After-effect Studies

Abstract

One of the first applications of Mössbauer spectroscopy was the study of the behaviour of an impurity atom in a metallic host matrix. The vibrational characteristics of such an atom are of fundamental importance to an understanding of lattice dynamics, and may be measured using the temperature dependence of the chemical isomer shift and recoilless fraction (see Chapter 6). There are however a number of other ways in which impurity effects can be used. In some instances the interest centres upon the impurity atom itself, as for example in semiconductors where the physical and chemical properties may be drastically altered by the nature of the impurity. In other cases the impurity atom is incorporated into the host with the intention of monitoring the properties of the latter. The incorporation of isotopically enriched impurities into metals, oxides and other ionic salts for use as Mössbauer absorbers has been extensively used for both purposes.