Direct determination of defect structures

Abstract

Abstract A procedure for the direct determination of defect structures is presented. The procedure uses the average structure to calculate starting phases. An iterative cycle of inverse Fourier transforms and interpretations of the scattering density is applied. Within each cycle the scattering density is interpreted to yield a structure deviating from the average structure by missing, replaced or shifted atoms. The procedure usually converges after a few cycles and allows a direct determination of substitutional and displacement disorder. By analyzing the correlations between different atoms, extended defects can be recognized. The current results are preliminary and have been limited to an idealized one dimensional situation, under the assumption of a negligible experimental resolution function.