Hiroshi Yanagimoto

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 solution system of FeOOH–NH 4 F·HF (aq.) with added boric acid by a novel liquid-phase deposition (LPD) method and is the first attempt to preparate iron oxide thin films by this method. A crystalline β-FeOOH thin film was formed directly on the substrate upon immersion into a mixed solution of FeOOH–NH 4 F·HF and H 3 BO 3 . The orientation of the deposited film differed according to the concentration of H 3 BO 3 in the solution. When the concentration of H 3 BO 3 was >0.30 mol dm -3 , the β-FeOOH thin film was preferentially oriented in the [211] direction. The β-FeOOH thin film formed was transformed into α-Fe 2 O 3 upon heat treatment in air flow. The α-Fe 2 O 3 thin films obtained were oriented in the [110] direction. The F content of the as-deposited β-FeOOH film was ca. 15% F/Fe and was reduced to 0.19% upon heat treatment.

Preparation and characterization of Au-dispersed TiO2 thin films by a liquid-phase deposition method

Au-dispersed TiO2(anatase) thin films have been prepared by a novel method, liquid-phase deposition (LPD). The deposited films were characterized by XRD, XPS, TEM and UV–VIS absorption spectroscopy. The results showed that the titanium oxide thin film containing AuIII ions was formed from a mixed solution of ammonium hexafluorotitanate, boric acid and tetrachloroauric acid. Heat treatment above 200 °C of the deposited film under flowing air produced dispersed Au metal particles, accompanied by the crystallization of titanium oxide as a matrix. The mean particle size of the dispersed Au particles was ca. 15 nm. The optical absorption band due to the surface plasmon resonance of the dispersed Au particles shifted toward longer wavelengths with increasing heat-treatment temperature.

Preparations of Polystyrene/Aluminum Hydroxide and Polystyrene/Alumina Composite Particles in an Ionic Liquid

Polystyrene (PS)/aluminum hydroxide (Al(OH)(3)) composite particles were successfully prepared by the sol-gel process of aluminum isopropoxide (Al(OPr(i))(3)) in a hydrophilic ionic liquid, 1-butyl-3-methylimidazolium tetrafluoroborate ([Bmim][BF(4)]) using ammonium hydroxide (NH(4)OH) as a catalyst in the presence of PS seed. Transmission electron microscopy observation of ultrathin cross-sections of the composite particles revealed that the composite particles had a core-shell morphology consisting of a PS core and a Al(OH)(3) shell having high crystallinity. The amount of secondary nucleated Al(OH)(3) could be reduced by dropwise addition of NH(4)OH. Moreover, PS/η-Al(2)O(3) composite particles were successfully prepared by heat treatment of PS/Al(OH)(3) at 300 °C in N(2) atmosphere, which is below the decomposition temperature of PS.

Preparation of boron nitride and polystyrene/boron nitride composite particles by dehydrogenation in ionic liquids

Boron nitride (BN) was prepared by the dehydrogenation of ammonia borane (AB) in an ionic liquid (1-butyl-3-methylimidazolium tetrafluoroborate, [Bmim][BF4]) at 300 °C, which is lower than the temperature of the general preparation method of BN and below the decomposition temperature of polystyrene (PS). The reaction was performed at 120 °C for 10 h under atmospheric pressure, and the product material was subsequently heated at 300 °C for 24 h under reduced pressure in [Bmim][BF4]. The reaction rate and final conversion increased when [Bmim][BF4] was used as the medium as compared to those observed in the bulk system (in the absence of the solvent system). Moreover, PS/BN composite particles were successfully prepared by dehydrogenation in [Bmim][BF4] in the presence of cross-linked PS seed particles. Transmission electron microscopy images of ultrathin cross-sections of the composite particles confirmed the core–shell morphology of the particles with a PS core and a BN shell.