Mössbauer Studies of Synthetic and Soil‐Occurring Aluminum‐Substituted Goethites

Abstract

Abstract Mössbauer spectroscopy of partially Al‐substituted synthetic goethites shows marked variation of the internal magnetic field ( H ) with Al substitution. Empirical relations are reported which allow using observed H values to estimate % Al in the oxides present in soil clay. Relaxation effects due to small particle size and substitution of Al 3+ for Fe 3+ complicate the spectra, and in many cases liquid nitrogen or liquid helium temperatures are necessary to resolve the components. However, the relaxation effects observed may be related qualitatively to particle size of the Fe oxides present. The utility of the Mössbauer technique was tested with a number of soil samples containing Al‐substituted goethite.