The Experts below are selected from a list of 285 Experts worldwide ranked by ideXlab platform
Yasufumi Otsubo - One of the best experts on this subject based on the ideXlab platform.
-
effects of polymeric dispersants on the rheology and uv protecting properties of complex suspensions of titanium diOxides and Zinc Oxides
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2008Co-Authors: Akio Nasu, Yasufumi OtsuboAbstract:Abstract Titanium dioxide (TiO2) and Zinc oxide (ZnO) particles are very effective as UV-protecting inorganic materials in cosmetic products, but they tend to form flocs in a liquid. Because the UV scattering of suspensions strongly depends on the floc size, the degree of flocculation can be evaluated by rheological technique. To control the flocculation level of complex suspensions, polyoxyethylene (POE)-modified silicones of ABA-type in which the POE groups are incorporated between terminal groups of dimethylpolysiloxane (DMPS) are used as dispersants. Based on the experimental results that the suspensions consisting of small flocs show low viscosity and high UV-protection, it is confirmed that the optimum HLB value which contributes to excellent UV scattering is lower for dispersants with higher molecular weight. In adsorption, the POE groups attach to the particle surfaces and the silicone groups are in an extended conformation. The steric stabilization mechanism is responsible for low viscosity of suspensions. Since the conformation of adsorbed chains is determined by the adsorption energy of POE and loss of conformational entropy of DMPS, the molecular weight of PEO and balance between PEO and DMPS play a crucial role in controlling the flocculation level and UV-protecting ability.
-
rheology and uv protecting properties of complex suspensions of titanium diOxides and Zinc Oxides
Journal of Colloid and Interface Science, 2007Co-Authors: Akio Nasu, Yasufumi OtsuboAbstract:Abstract Ultra-fine particles of titanium dioxide (TiO 2 ) and Zinc Oxides (ZnO) are very attractive as UV-protecting ingredients in cosmetic products. The UV-scattering behavior of complex suspensions in a silicone oil is studied in relation to rheological properties. To control the dispersion stability of suspensions, three polyoxyethylene (POE)-modified silicones of branch-type, (AB) n -type, and ABA-type are used as dispersants. Irrespective of molecular structure, the dispersants can stabilize the TiO 2 and ZnO particles and the flow of both single suspensions is Newtonian with low viscosity. However, the Newtonian flow profiles and high dispersion states are maintained only for complex suspensions prepared with ABA-type dispersant. Since the POE groups which are incorporated between terminal silicones groups attach to the particle surfaces, the steric stabilization is responsible for low viscosity and high dispersions. Because the UV scattering of suspensions is determined by the sizes of flocculated structures, the high transmittance in the visible ranges and low transmittance in the UVA and UVB ranges can be achieved in the presence of ABA-type dispersant.
J M Tarascon - One of the best experts on this subject based on the ideXlab platform.
-
influence of tin doping on the structural and physical properties of indium Zinc Oxides thin films deposited by pulsed laser deposition
Thin Solid Films, 2002Co-Authors: N Naghavi, L Dupont, C Marcel, C Maugy, Claude Guery, J M TarasconAbstract:a ´´ ´ Laboratoire d'Electrochimie et de Chimie Analytique (UMR 7575), Ecole Nationale Superieure de Chimie de Paris, b ´ Abstract A detailed investigation of the structural and opto-electrical properties of tin-doped indium-Zinc oxide thin films prepared by pulsed laser deposition was carried out.The substitution of indium for tin in Zn In O compounds (ks2, 3 and 5 )( which k 2 kq3 structure is a mixture of homologous phases with different k, but mostly composed of the polytype having the target composition) led to a conductivity enhancement, caused by an increase in carrier concentration at low doping levels, whereas for higher doping levels a decrease in conductivity and carrier concentration together with an amorphisation of the films was noted.The best electrical properties (ss2500 Sycm) were obtained for the Zn In Sn O doped films having a layered Zn In O -type 21 . 9 0. 1 5 qd k 2 kq3 structure with essentially ks2.Independently of the composition an 85-90% average transmittance in the visible region was obtained.In contrast the band gap of the Sn-doped film slightly increased with tin ratio, in agreement with the Burstein-Moss theory. � 2002 Elsevier Science B.V. All rights reserved.
-
systematic study and performance optimization of transparent conducting indium Zinc Oxides thin films
Electrochimica Acta, 2001Co-Authors: N Naghavi, L Dupont, C Marcel, C Maugy, Barbara Laik, A Rougier, Claude Guery, J M TarasconAbstract:To optimize the physical properties of In 2 O 3 -ZnO pulsed laser deposited thin films, we embarked on a systematic study of their microstructural characterization and transport properties. We found that the electrical properties of the films are greatly governed by their microstructure, which evolves from granular to fiber and to columnar textures, as we go from cubic In 2 O 3 to hexagonal ZnO via Zn k In 2 O k+3 layered structure in the binary In 2 O 3 ZnO phase diagram. Maximum conductivity is reached for a Zn/(Zn + In) = 0.5 (at.) composition having a layered Zn k In 2 O k+3 - type structure with essentially k = 2, which was synthesized for the first time. Electrochemical measurements show that this film can be used as a transparent electrode in electrochromic devices operating either in an aqueous or organic medium.
Jaegwan Chung - One of the best experts on this subject based on the ideXlab platform.
-
amorphous gallium indium Zinc oxide thin film transistors sensitive to oxygen molecules
Applied Physics Letters, 2007Co-Authors: Donghun Kang, Ihun Song, Jaechoel Park, Youngsoo Park, Jaegwan ChungAbstract:In this study, the authors report characteristic of indium gallium Zinc Oxides (GIZOs) which is strongly associated with the film surface. In ambient air, turn-on voltage of GIZO thin film transistors is approximately −7V. However, at the pressure of 8×10−6Torr, the turn-on voltage dramatically shifts to nearly −47V of the negative gate bias direction. When the oxygen is introduced in the chamber, the turn-on voltage returns to the normal value, that of air. It is believed that the adsorbed oxygen forms depletion layer below the surface, resulting in Von shifts. The carrier concentration of the channel varies from 1×1019to1×1020cm−3 due to oxygen adsorption.
Masatake Haruta - One of the best experts on this subject based on the ideXlab platform.
-
carbon dioxide and carbon monoxide hydrogenation over gold supported on titanium iron and Zinc Oxides
Applied Catalysis A-general, 1995Co-Authors: Hiroaki Sakurai, Masatake HarutaAbstract:Abstract Gold deposited on TiO 2 , Fe 2 O 3 , ZnO and ZnFe 2 O 4 with high dispersion was found to be active for the hydrogenation of both carbon dioxide and carbon monoxide at temperatures between 150 and 400°C. Over the above catalysts, methanol was produced more readily from carbon dioxide than from carbon monoxide. In particular, Au/ZnO and Au/ZnFe 2 O 4 showed high methanol selectivities from carbon dioxide, which were comparable to those obtained for copper catalysts. As for methanol synthesis from carbon monoxide, only Au/ZnO gave appreciable yields with similar selectivity as copper catalysts. The comparison between experimental and thermodynamic data proved that over all the catalysts except for Au/TiO 2 three reactions, namely between carbon dioxide and methanol, carbon monoxide and methanol, carbon dioxide and carbon monoxide, simultaneously reached equilibria at temperatures above 300°C and that the methanol yield decreased with further increase in temperature. Hydrocarbons were formed at high temperatures and the resulting water was also involved in the above equilibria. As a main hydrocarbon product, methane was obtained much more selectively from carbon dioxide than from carbon monoxide. Ethane and propane were also produced from carbon dioxide and carbon monoxide over gold supported on reduced iron Oxides.
-
Carbon dioxide and carbon monoxide hydrogenation over gold supported on titanium, iron, and Zinc Oxides
Applied Catalysis A General, 1995Co-Authors: Hiroaki Sakurai, Masatake HarutaAbstract:Gold deposited on TiO2, Fe2O3, ZnO and ZnFe2O4 with high dispersion was found to be active for the hydrogenation of both carbon dioxide and carbon monoxide at temperatures between 150 and 400°C. Over the above catalysts, methanol was produced more readily from carbon dioxide than from carbon monoxide. In particular, Au/ZnO and Au/ZnFe2O4 showed high methanol selectivities from carbon dioxide, which were comparable to those obtained for copper catalysts. As for methanol synthesis from carbon monoxide, only Au/ZnO gave appreciable yields with similar selectivity as copper catalysts. The comparison between experimental and thermodynamic data proved that over all the catalysts except for Au/TiO2 three reactions, namely between carbon dioxide and methanol, carbon monoxide and methanol, carbon dioxide and carbon monoxide, simultaneously reached equilibria at temperatures above 300°C and that the methanol yield decreased with further increase in temperature. Hydrocarbons were formed at high temperatures and the resulting water was also involved in the above equilibria. As a main hydrocarbon product, methane was obtained much more selectively from carbon dioxide than from carbon monoxide. Ethane and propane were also produced from carbon dioxide and carbon monoxide over gold supported on reduced iron Oxides. © 1995 Elsevier Science B.V. All rights reserved.
N Naghavi - One of the best experts on this subject based on the ideXlab platform.
-
influence of tin doping on the structural and physical properties of indium Zinc Oxides thin films deposited by pulsed laser deposition
Thin Solid Films, 2002Co-Authors: N Naghavi, L Dupont, C Marcel, C Maugy, Claude Guery, J M TarasconAbstract:a ´´ ´ Laboratoire d'Electrochimie et de Chimie Analytique (UMR 7575), Ecole Nationale Superieure de Chimie de Paris, b ´ Abstract A detailed investigation of the structural and opto-electrical properties of tin-doped indium-Zinc oxide thin films prepared by pulsed laser deposition was carried out.The substitution of indium for tin in Zn In O compounds (ks2, 3 and 5 )( which k 2 kq3 structure is a mixture of homologous phases with different k, but mostly composed of the polytype having the target composition) led to a conductivity enhancement, caused by an increase in carrier concentration at low doping levels, whereas for higher doping levels a decrease in conductivity and carrier concentration together with an amorphisation of the films was noted.The best electrical properties (ss2500 Sycm) were obtained for the Zn In Sn O doped films having a layered Zn In O -type 21 . 9 0. 1 5 qd k 2 kq3 structure with essentially ks2.Independently of the composition an 85-90% average transmittance in the visible region was obtained.In contrast the band gap of the Sn-doped film slightly increased with tin ratio, in agreement with the Burstein-Moss theory. � 2002 Elsevier Science B.V. All rights reserved.
-
systematic study and performance optimization of transparent conducting indium Zinc Oxides thin films
Electrochimica Acta, 2001Co-Authors: N Naghavi, L Dupont, C Marcel, C Maugy, Barbara Laik, A Rougier, Claude Guery, J M TarasconAbstract:To optimize the physical properties of In 2 O 3 -ZnO pulsed laser deposited thin films, we embarked on a systematic study of their microstructural characterization and transport properties. We found that the electrical properties of the films are greatly governed by their microstructure, which evolves from granular to fiber and to columnar textures, as we go from cubic In 2 O 3 to hexagonal ZnO via Zn k In 2 O k+3 layered structure in the binary In 2 O 3 ZnO phase diagram. Maximum conductivity is reached for a Zn/(Zn + In) = 0.5 (at.) composition having a layered Zn k In 2 O k+3 - type structure with essentially k = 2, which was synthesized for the first time. Electrochemical measurements show that this film can be used as a transparent electrode in electrochromic devices operating either in an aqueous or organic medium.
