Akaganeite-type beta-FeO(OH) nanocrystals: preparation and characterization

The preparation of nanocrystalline beta -FeO(OH) by precipitation from an a queous solution of the chloride salt and the investigation of relative surf ace properties of the iron oxyhydroxide gel were the aims of this study. A new advantageous method using ammonium carbonate as precipitating agent is presented by which the synthesis of akaganeite (beta -FeO(OH) was accomplis hed. Akaganeite was transformed to iron oxide hydroxide (FeOOH) and finally to hematite (alpha -Fe2O3) after thermal treatment at 473 and 673 K, respe ctively. The use of a volatile agent for the hydrolysis process, the specia l method of chloride ion removal, as well as the freeze-drying technique, l ed to the production of a material consisting of nanocrystals with high sur face area and defined pore size distribution. (C) 2001 Elsevier Science B.V . All rights reserved.