In this study, diffusion mechanism of iron impurities in bulk YBa2Cu3O7 (YBaCuO) superconductor prepared by standart solid state reaction method and its effect on lattice structure under different magnetic field have been examined. Correlation between characteristic X-ray intensities and surface dopant density were investigated. The effects of different magnetic field intensities on crystal structure of iron diffused samples have been investigated by quantitative Energy Dispersive X-Ray Fluorescence (EDXRF) and X-ray Diffraction (XRD) techniques. It was found that Fe diffusion increases with increasing magnetic field. (c) 2005 Elsevier B.V. All rights reserved.