Papers by Keyword: H₂O

Abstract: Group III–V compound semiconductors are attracting attention as new channel materials that have higher carrier mobility than Si. However, defects easily occur at the interface between the semiconductor and insulator film, which degrades performance. In an earlier study, we demonstrated that the interfacial properties of InP are degraded by the growth of In₂O₃ and that In₂O₃ grows better in water than in air. Therefore, it is necessary to suppress the growth of In₂O₃ to improve the interfacial properties of InP. In this work, we focused on functional water, which can be controlled by adjusting the water conditions, and investigated the growth behavior of In₂O₃ in functional water. As a result, we found that the growth is suppressed in the low-pH range and in hydrogen water. It is important that H⁺ ions reduce OH⁻ ions, which contributes to the reaction with InP.

Abstract: Zeolite 13X@SiO₂ composites have been prepared using TEOS and CTAB as the silica source and template respectively, via hydrothermal reaction. The approach of synthesizing zeolite 13X@SiO₂ core-shell structures has been adopted followed by external surface modification by silane to achieve hydrophobicity. The materials were characterized by XRD, SEM, FTIR, etc. The results show that the zeolite 13X@SiO₂ core-shells structures have been prepared and their properties are maintained even after the modification. The CO₂ adsorption capacity was well maintained after silylation, however, the adsorption of water on samples was effectively inhibited by the surface modification.

Abstract: As fossil fuels are becoming less reliable and more costly, the Proton Exchange Membrane Fuel Cell (PEMFC) is emerging as the primary candidate to replace the stationary and transport applications. In this study numerical simulation on PEMFC is done by commercially available Computational Fluid Dynamics (CFD) software. A three-dimensional, model of a single PEM Fuel cell with serpentine flow field design has been used for the study. The numerical model is 3-D steady, incompressible, single phase and isothermal includes the governing of mass, momentum, energy, and species along with electrochemical equations. All of these equations are simultaneously solved in order to get current flux density and H₂, O₂ and H₂O fractions along the flow field design.

Abstract: Interest in molecular materials has been driven in large part by their various and prosperous applications, especially in the domain of organic electronics, where they offer many advantages as well as alternative approaches compared to their inorganic counterparts. Most of conductometric transducers are resistors^[[ and transistors^[[[, but rarely diodes^[6]. In our laboratory, we designed and characterized new molecular material based devices. Molecular Semiconductor Doped Insulator (MSDI) heterojunctions were built around a heterojunction between a Molecular Semiconductor (MS) and a Doped Insulator (DI)^[7][8]. This new device exhibits interesting electronic properties that allow ammonia sensing in a large humidity range at room temperature.

Abstract: Hydrothermal treatment has been conducted to create porous glass or ceramics as value-added materials for the recycling of slag and glass. Under hydrothermal conditions, slag and glass react with a high pressurized H₂O and hydrate glass phase containing plenty of H₂O is formed to connect raw materials particles to make ceramic materials. The hydrothermal process takes advantages of energy costs, because it can be operated at a low temperature compared to conventional sintering processes. Since the hydrothermal process uses H₂O to fabricate ceramic materials, it can be regarded as energy-saving, eco-friendly, and spontaneous materials processing. In the present study, we introduce some applications of hydrothermal treatments to slag / glass to produce functional porous ceramic materials.

Abstract: We present the results from first principle calculations of H₂O adsorption on oxygen-covered Fe (100) surface. The calculations are based on a density-functional theory, surface modeling which uses supercell slab models. As a surface oxygen coverage increases, the surface is not activated, which makes the adsorption of water molecules on Fe surface unfavorable. It has been found that the surface covered oxygen exerts an influence on the adsorption of H₂O molecule on Fe surface.

Abstract: Highly aligned carbon nanotube arrays (HACNTAs) were synthesized on a stainless steel substrate from a methanol solution of Co(Ⅲ) acetylacetonate by the one-step liquid-phase synthesis, and effects of H2O addition on the HACNTA growth were examined. The growth rate was considerably accelerated, and the lifetime of the catalysts was prolonged by addition of a small amount of H2O. HACNTAs with over 400 m thickness were formed on the side surfaces of the substrate by resistance-heating for one hour. This suggests that the added H2O removes deposited amorphous carbons from the catalyst surfaces and consequently accelerates the growth rate.

Abstract: The oxidation of iron in dry O2 and in wet O2 (40% H2O) has been studied at 600°C. The oxide microstructure was investigated by SEM/EDX, FIB and XRD. Iron forms a layered scale in dry and wet oxygen at 600°C. The scale consists of a top hematite layer, a middle magnetite layer and a wüstite layer close to the scale metal interface. All three layers grow with time, but with different growth rates, the overall growth being approximately parabolic. The presence of water vapour increases the rate of oxidation and affects the evolution of the oxide microstructure. The higher rate of oxidation in the presence of water vapour is due to an increased growth rate of the magnetite layer and, especially, of the hematite layer, while the growth of the wüstite layer is not affected. It is suggested that water vapour influences grain boundary transport in the hematite layer.