PREPARATION AND CHARACTERIZATION OF IRON OXYHYDROXIDE AND IRON-OXIDE THIN-FILMS BY LIQUID-PHASE DEPOSITION

Iron oxyhydroxide thin films have been prepared from the aqueous solut ion system of FeOOH-NH4F . HF (aq.) with added boric acid by a novel l iquid-phase deposition (LPD) method and is the first attempt to prepar ate iron oxide thin films by this method. A crystalline beta-FeOOH thi n film was formed directly on the substrate upon immersion into a mixe d solution of FeOOH-NH4F . HF and H3BO3. The orientation of the deposi ted film differed according to the concentration of H3BO3 in the solut ion. When the concentration of H3BO3 was >0.30 mol dm(-3), the beta-Fe OOH thin film was preferentially oriented in the [211] direction. The beta-FeOOH thin film formed was transformed into alpha-Fe2O3 upon heat treatment in air how. The alpha-Fe3O3 thin films obtained were orient ed in the [110] direction. The F content of the as-deposited beta-FeOO H film was ca. 15% F/Fe and was reduced to 0.19% upon heat treatment.