Morphological control – Iron Oxide

Systems studied in collaboration with the Nanochemistry Research Institute at Curtin University of Technology were methyl nitrilo dimethylenephosphonic acid (MNDP) and ethylenediamine tetraphosphonic acid (EDTP) in contact with hematite (α-Fe2O3)[1]. We have predicted and verified by experiment how the morphology is affected by the presence of the additives. The additives were shown to generally have an affinity for the (222) and (110) surfaces, however the EDTP also showed a high affinity for the (10-1) surface which was not favoured at all by the MNDP additive. The model therefore predicts an increase in the morphology of the (222) surface fraction as well as for the EDTP the likely appearance of the highly stabilized (10-1) surface as shown in the figure below.

 The predicted modification of the hydroxylated equilibrium morphology by the two additives MNDP and EDTP [1]

[1] Aschauer U., Jones F., Richmond W., Bowen P., Rohl A. L., Parkinson G. M., Hofman H., Growth modification of hematite by phosphonate additives, Journal of Crystal Growth, 310(3), (2008), 688-698, (Link to article)