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

The preparation of nanocrystalline beta -FeO(OH) by precipitation from an aqueous solution of the chloride salt and the investigation of relative surface 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 accomplished. Akaganeite was transformed to iron oxide hydroxide (FeOOH) and finally to hematite (alpha -Fe2O3) after thermal treatment at 473 and 673 K, respectively. The use of a volatile agent for the hydrolysis process, the special method of chloride ion removal, as well as the freeze-drying technique, led to the production of a material consisting of nanocrystals with high surface area and defined pore size distribution. (C) 2001 Elsevier Science B.V. All rights reserved.