DIRECT DETERMINATION OF DEFECT STRUCTURES

A procedure for the direct determination of defect structures is prese nted. The procedure uses the average structure to calculate starting p hases. An iterative cycle of inverse Fourier transforms and interpreta tions of the scattering density is applied. Within each cycle the scat tering 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 determinatio n of substitutional and displacement disorder. By analyzing the correl ations between different atoms, extended defects can be recognized. Th e current results are preliminary and have been limited to an idealize d one dimensional situation, under the assumption of a negligible expe rimental resolution function.