Nobukazu Kinomura

Preparation of Oriented Titanium Phosphate and Tin Phosphate/ Polyaniline Hybrid Films by Electrochemical Deposition

The preparation of hybrid films of metal (Ti and Sn) phosphate nanosheets and polyaniline by simultaneous electrophoretic and electrolytic deposition was performed in an acetonitrile solvent. Emeraldine polyaniline was intercalated between the phosphate nanosheets with a monolayer arrangement. The obtained hybrid films were several tens of micrometers in thickness. The ratio of incorporated polyaniline to metal phosphate in the hybrid films reaches to around 0.45 and 0.30 at suitable concentrations of tetrabutylammonium hydroxide (TBAOH). These amounts correspond with occupancy of polyaniline in the interlayer gallery of several tens percent. Fractions of voids in a horizontal direction were around 22 and 1% in titanium phosphate/polyaniline and tin phosphate/polyaniline hybrid films, respectively. Thus, anodic electrodeposition makes it possible to form thick films of intercalation compounds of alpha-titanium and tin phosphates with polyaniline. These hybrid films were examined for redox activity. The cyclic voltammetry results of these films confirmed that the hybrid films have redox activity by polyaniline. For these voltammograms, the maximum current was observed in the tin phosphate/polyaniline hybrid deposited for 15 min. The redox activity of these hybrids possibly depends on the mesoscopic texture of the film, especially on the amount of voids in a horizontal direction.

Ferroelectric property of (Ba,Bi)(Ti,M)O3 (M; Cu, Mn, Al, Fe, In, Y, Yb) ceramics

Two types of solid solutions, (Ba1-2xBi2x)(CuxTi1-x)O3 (x ≤ 0.04) and (Ba1-xBix)(MxTi1-x)O3 (M; Al, Mn, Fe, In, Y, Yb; x ≤ 0.03) were prepared by conventional high temperature reaction. For the solid solution of (Ba1-2xBi2x)(CuxTi1-x)O3 single phases with the tetragonal cell was obtained in the region of x ≤ 0.04 and for the solid solutions of (Ba1-xBix)(MxTi1-x)O3 (M; Al, Mn, Fe, In, Y, Yb) single phases with the tetragonal cell was observed in the region of x ≤ 0.03 except the sample of M = Al in which a small amount of the second phase was contained. In these solid solutions the Tc increased with the value of x except for M = Al, and was 144.7°C for x = 0.020 of M = Cu, and the highest Tc was observed for x = 0.020 of every M atom and the order of the highest Tc was Cu (144.7°C), Y (141.4°C), Yb (140.8°C), In (138.5°C), Mn (135.5°C) and Fe (131.3°C). The highest apparent piezoelectric constant, (d33 = 258 pm/V) in these solid solutions was observed for x = 0.010 of Al.

Preparation of α-Fe2O3 particles with controlled shape and size via a facile hydrothermal route

α-Fe2O3 particles with controlled shape and size have been prepared by a facile hydrothermal reaction between ferric chloride hexahydrate (FeCl36H2O) and sodium hydroxide (NaOH) at 160°C. X-ray powder diffraction pattern indicates that the product is single-phase of α-Fe2O3.The morphology of α-Fe2O3 particles changed as homogenous sphere, top-shape and cube, depending on solution pH. Meanwhile, monodispersed cube particles of α-Fe2O3 are also prepared under the same conditions using surfactant of hexadecyl trimethyl ammonium bromide (CTAB). The experimental results suggest that particle size can be controlled by adjusting the solution pH and amount of CTAB.

Structure and electrical properties of the new pyrochlore‐type protonic solid electrolyte K0.88Nb2O7.58H4.28

Single-crystal, synchrotron powder X-ray diffraction and neutron powder diffraction studies of the novel pyrochlore-type compound with the structural formula K(0.88)(OH)(0.54)H(1.66)(H(2)O)(1.04)Nb(2)O(6) suggests that the water molecules are located in 32e sites, and the hydroxide ions and potassium ions are located in 16d sites with a significant amount of free protons in 96g sites. The total weight loss at temperatures up to 773 K is only about 8%, suggesting the oxygen escape from 48f sites can be excluded and free protons must be preserved in the structure. The bulk conductivity in ambient air reaches 10(-2) S cm(-1) at 623 K. Owing to the extended stability range and resistance to water solubility, the compound can be considered as a candidate for intermediate temperature solid-oxide fuel-cell applications.