Modification of Phosphate Hopeite Crystals and Structural Determination of the High Durable Modified Crystals by Means of Extended X-ray Absorption Fine Structure

Using hopeite crystals as phosphate layer formed on zinc coated steels of automobile body, EXAFS (Extended X-ray Absorption Fine Structure) method was applied to analyze the local structure of heavy metal components contained in these crystals. Analysis was done by observing XANES (X-ray Absorption Near Edge Structure) spectra, Fourier transforms of EXAFS and reverse operations of Fourier transforms for these functional materials. The data supported that manganese components existed as Mn(II) in the modified hopeite crystals with a structure of Zn₃-_XMn_X(PO₄)₂·4H₂O. Furthermore, curve fitting analysis of EXAFS provided more detailed information of the chemical structure.