Glancing angle EXAFS investigation of the habit modification of ADP by the incorporation of iron

Abstract The application of glancing angle X-ray extended X-ray absorption fine structure (EXAFS) to studies of ionic adsorbed habit modifiers is outlined and applied to the case of Fe 3+ doped ammonium dihydrogen phosphate. These studies reveal that Fe 3+ ions adsorbed on (100) surfaces are coordinated with two oxygen and two phosphorous atoms. Comparison was made of the experimental spectra with spectra calculated for Fe 3+ occupying interstitial and substitutional sites and indicates that the Fe 3+ occupies the interstitial site (0.25, 0.22, 0.125). Structurally the incorporation appears to disturb the hydrogen bonding network in this material which results in the generation of lattice strain, the latter, in turn, causes a reduction in the growth rate of the modified surface. This habit modification mechanism contrasts with the usually accepted models of surface step/terrace blocking.