A. Tsuzuki

Crystal structures of TiO2 thin coatings prepared from the alkoxide solution via the dip-coating technique affecting the photocatalytic decomposition of aqueous acetic acid

TiO2 coatings with different crystal structures were prepared from alkoxide solutions via the dip-coating technique. The physical properties, except the crystal structure, were adjusted to distinguish the effect of crystal structure on their photocatalytic property. The results of photocatalytic measurements using TiO2 coatings with different crystal structures showed that the decomposition of aqueous acetic acid was enhanced by the content of anatase phase.

Morphology of thin anatase coatings prepared from alkoxide solutions containing organic polymer, affecting the photocatalytic decomposition of aqueous acetic acid

Porous anatase coatings were prepared from alkoxide solutions containing organic polymer by a dip-coating technique. The morphology of the coatings, such as pore size, pore distribution and thickness, was controlled. The effects of the morphology of the porous anatase coatings on the photocatalytic activity for the photocatalytic decomposition of aqueous acetic acid were examined.

preparation and ferroelectric properties of sol-gel-derived (Pb, Ca)TiO3 thin films

Etude des proprietes structurale et ferroelectriques de couches de (Pb 1−x Ca x )TiO 3 (0,0≤x≤0,35) preparees par la methode sol-gel

Critical currents of YBa2Cu3Oy thick films prepared by liquid phase epitaxial growth

We have succeeded in preparing c‐axis oriented high‐Jc YBa2Cu3Oy films on MgO(100) substrate by the liquid phase epitaxy (LPE) technique. The growth rate was typically about 2 μm/min, which was 10–102 times larger than that by ordinary vapor growth techniques. The film thickness ranged 10–50 μm by choosing the dipping time. The Tc of the best film exceeded 88 K after oxygen annealing, and the transport Jc was 1.1×105 A/cm2 at 77 K and 0 T. In‐field Jc’s at 77 K and 1.5 T were 2.8×104 A/cm2 and 2.0×104 A/cm2 for the B⊥ab plane and B∥ab plane, respectively. In addition, the peak effect of Jc was observed at several tesla for B∥ab plane geometry. Based on the microstructure observed by high resolution transmission electron microscopy, the relevant peak effect is considered to be caused by stacking faults which act as a field induced pinning center.

Chemical processing and characterization of spinel-type thermistor powder in the Mn-Ni-Fe oxide system

The coprecipitated Mn-Ni-Fe oxalate was prepared from the mixed sulfate solution by optimum pH control. The chemical composition agreed well with that of the starting solution, and the thermal decomposition of the Mn-Ni-Fe oxalate in air below 600 °C led to the direct formation of cubic spinel phase with fine particle size. The sinterability of the calcined powder, the stability of cubic spinel phase and the influence of annealing temperature on electrical properties of the sintered bodies, were investigated.

Elaboration et photoconduction des films de Bi2O3-MO3 (M = Mo OU W) obtenus par hypertrempe

Abstract The Bi2O3-MO3 films (M = Mo or W) were prepared by a rapid quenching technique using a twin-roller type equipment. The quenched films containing from 2.5 to 5 mol% MoO3 or WO3 precipitated only a tetragonal phase. By further increase of these oxide additives, a cubic phase (δ-phase) was formed coexisting with the tetragonal one. The lowest content of the additives to form singly the δ-phase was 12.5% for MoO3 and 10% for WO3 respectively. The lattice parameters of the tetragonal phase tended to increase with increasing amount of additives. The quenched films, although consisting either of the tetragonal phase, the cubic phase or their mixture, decomposed to form both α-Bi2O3 and tetragonal phase, on annealing at a temperature between 350 and 550°C. As a result of the determination of IR absorption spectra, it was suggested that a certain amount of pentavalent Bi ions was contained in the quenched phase. The quenched films were also characterized by a high photoconductivity. The highest photoconductivity appeared when a beam of about 500 nm in wavelength was irradiated on the film. The photoconduction was observed in all films containing less than 12.5% additives.

Structural and dielectric properties in the system LiTaO3-WO3

Phase transition in the (1-x)LiTaO3-xWO3 solid solution system has been studied by means of X-ray diffraction and dielectric measurements. Nonstoichiometric solid solutions with a LiTaO3 structure are formed in the range of 0 < x ≤ 0.4, and the introduction of WO3 into LiTaO3 causes cation vacancies in the Lisites. The axial ratio (c/a) of the hexagonal cell and the ferroelectric Curie temperature decrease with the increase of x. A trirutile compound LiTaWO6 (x=0.5) exhibits photochromism.

Sol-gel processing and pyroelectric properties of lanthanum-modified PbTiO3 thin films

Thin films in the system (Pb 1-x La 2x/3 )TiO 3 (0.0≤x≤0.2) were successfully prepared through the sol-gel process. The films fired at 650°C on Pt substrate were uniform and crack-free. Their structural and electrical propertieswere characterized, and D-E hysteresis loops were observed

Effect of rare-earth oxide addition on the thermal conductivity of sintered aluminium nitride

The densification of A1N ceramics and the improvement of its thermal conductivity are typically achieved by the addition of a small amount of oxides. The effects of oxide addition on the density and thermal conductivity of sintered A1N were investigated by Tsuge and co-workers [1, 2]. They found that the alkaliand rare-earth oxides (Re203) were useful additives for the fabrication of fully densified and highly thermally conductive A1N; Y203 is an especially good sintering additive. In the A1N sintering process, Y203 additive reacts with the surface oxide layer of A1N particles, forms the liquid phase of the Y A I O N system, causes the precipitation of yttrium-aluminium-oxide phases such as Y4A1209 (2Y203.A1203) in grain boundaries and lowers the oxygen content dissolved in A1N grains, and then the thermal conductivity of sintered A1N increases [2]. However, the effects of Re203 addition other than Y203 on the thermal conductivity of A1N have not been studied in depth. Recently A1N sintering with Y203 additive under reducing nitrogen gas atmosphere was reported to be a useful method to obtain sintered bodies with high thermal conductivity (>150 W m -a K -1) [3-7]. In this study the effects of Re203 addition on the thermal conductivity of A1N specimens sintered in reducing nitrogen atmosphere were investigated. A commercial A1N powder (Tokuyama Soda Co., Tokyo) with an average particle size of 0.6/xm and a specific surface area of 3.2 m 2 g-1 was used in this research. According to the manufacturer, this powder contains 1 wt % oxygen, 220 p.p.m, carbon and trace amounts of iron, calcium and silicon. In this work ND203, Sm203, Gd203, Dy203, Er203 and Yb20 3 powders (Hokko Chemicals Co., Tokyo) were used as the Re203 additives. I mol % of each of the rare-earth oxide powders as sintering aids were added, respectively, to the raw A1N powder. These powders were mixed in ethanol in a ball mill. After drying, the mixed powder was formed into pellets 14 mm in diameter and 8 mm high using a stainless steel die, and then cold isostatically pressed (CIPed) under 200 MPa pressure for 60 s. The CIPed pellets were placed in a graphite crucible, and then sintered using a graphite heater furnance at temperatures of 1773, 1873, 1973, 2073 and 2173 K for 1 and 3 h under 0.1 MPa nitrogen atmosphere. Furthermore, the CIPed samples were sintered in a graphite crucible with A1N packing powder in order to investigate the effect of the sintering atmosphere. The heating rate was 0.17 Ks Gd203 > Er203 > Yb203 >Nd203 >Sm203 addition. On the other hand, in sintering with packing powder, the thermal conductivity of A1N specimens with Re203 were about 95 W m -1K -1. The maximum thermal conductivity of A1N ceramics obtained in this work was 195 W m -1K -a for Dy203 addition. The results for the oxygen content of sintered A1N with the Re203 are shown in Fig. 2. The oxygen content of A1N specimens sintered without packing

New Oxygen-Deficient Perovskite Phase, La1-xSrxCuO3-y (0.20≦x≦0.25)

In a given system, a new nonstoichiometric perovskite solid solution was found to exist in a narrow range of 0.20x0.25. This perovskite phase has a tetragonal distortion based on a Jahn-Teller effect of the Cu ion. The lattice parameters are closely related to those of the simple cubic perovskite: a=10.834(1) A, c=3.8638(4) A for La0.75Sr0.25CuO2.44 and a=10.851(1) A, c=3.8623(6) A for La0.80Sr0.20CuO2.47, where a2√2c. These perovskites are metallic conductors and no superconducting transition has been observed in a measured temperature range of 77–300 K.