The Experts below are selected from a list of 9588 Experts worldwide ranked by ideXlab platform
Hiroaki Tsuchiya - One of the best experts on this subject based on the ideXlab platform.
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Semiconductor properties and protective role of passive films of iron base alloys
Corrosion Science, 2007Co-Authors: Shinji Fujimoto, Hiroaki TsuchiyaAbstract:Abstract Semiconductor properties of passive films formed on the Fe–18Cr alloy in a borate buffer solution (pH = 8.4) and 0.1 M H 2 SO 4 solution were examined using a photoelectrochemical spectroscopy and an electrochemical impedance spectroscopy. Photo current reveals two photo action spectra that derived from outer hydroxide and inner oxide layers. A typical n-type Semiconductor behaviour is observed by both photo current and impedance for the passive films formed in the borate buffer solution. On the other hand, a negative photo current generated, the absolute value of which decreased as applied potential increased in the sulfuric acid solution. This indicates that the passive film behaves as a p-type Semiconductor. However, Mott–Schottky plot revealed the typical n-type Semiconductor Property. It is concluded that the passive film on the Fe–18Cr alloy formed in the borate buffer solution is composed of both n-type outer hydroxide and inner oxide layers. On the other hand, the passive film of the Fe–18Cr alloy in the sulphuric acid consists of p-type oxide and n-type hydroxide layers. The behaviour of passive film growth and corrosion was discussed in terms of the electronic structure in the passive film.
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Semiconductor Property of passive films and corrosion behavior of fe cr alloys
2006Co-Authors: Shinji Fujimoto, Hiroaki TsuchiyaAbstract:Knowledge of the structure and properties of oxide films of metals and alloys is important for understanding corrosion behaviour, because the protective action of most highly corrosion resistant metals and alloys essentially derives from passivity which is caused by an extremely thin oxide and/or hydroxide surface layer. Passivity of Fe-Cr alloys is one of the most important topics in corrosion science, because alloyed Cr is enriched in the passive film to act in a very important role regarding protection. Therefore, passive films on Fe-Cr alloys have been characterized by various ultrahigh vacuum (UHV) analytical techniques such as Auger electron spectroscopy (AES) and X-ray photoelectron spectroscopy (XPS). Such UHV surface characterization techniques cause specimens to be modified under quite different environmental conditions compared with those in which passive films are formed. Therefore, in situ electrochemical surface characterization techniques have been tried. The author of this work reported the photoelectrochemical response and electrochemical impedance spectroscopy of passive films on Fe-Cr alloys to reveal differences in electronic structure of passive films formed in a sulphuric acid and a borate buffer solution [1–3]. In the present chapter, the author summarizes the photoelectrochemical response of passive films on Fe-18Cr alloy comparing with the Mott-Schottky relation, which is correlated to corrosion behaviour.
Fuhui Wang - One of the best experts on this subject based on the ideXlab platform.
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electrochemical corrosion behavior of nanocrystalline materials a review
Journal of Materials Science & Technology, 2010Co-Authors: Ying Li, Fuhui WangAbstract:Nanocrystallization significantly influences the electrochemical corrosion behaviors of metals/alloys in liquid system. In active dissolution, nanocrystallization accelerates the corrosion reactions. If the corrosion products are dissoluble, the corrosion rate is increased by nanocrystallization; if the corrosion products are insoluble, the corrosion rate is decreased on the contrary because the corrosion products act as a block layer to delay the dissolution. In passivation, nanocrystallization changes the composition of the passive film, and results into different morphology and growth process of the passive film, both of which improves the formation of compact film and influences the Semiconductor Property. It influences the passivation depending on fast element diffusion and special adsorbed ability. The small grain size improves the element diffusion, which leads to the different composition of passive film (passive elements enrichment such as Cr, Ti). The small grain size also changes the surface condition, which influences the ions adsorption. All increase the corrosion resistance of materials. In local corrosion, nanocrystallization increases the unstable points on the surface of the materials, which increases the possibility of local corrosion. However, the excellent ability of element diffusion helps heal the local corrosion points, which inhibits the growth of the local corrosion.
Shinji Fujimoto - One of the best experts on this subject based on the ideXlab platform.
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Semiconductor properties and protective role of passive films of iron base alloys
Corrosion Science, 2007Co-Authors: Shinji Fujimoto, Hiroaki TsuchiyaAbstract:Abstract Semiconductor properties of passive films formed on the Fe–18Cr alloy in a borate buffer solution (pH = 8.4) and 0.1 M H 2 SO 4 solution were examined using a photoelectrochemical spectroscopy and an electrochemical impedance spectroscopy. Photo current reveals two photo action spectra that derived from outer hydroxide and inner oxide layers. A typical n-type Semiconductor behaviour is observed by both photo current and impedance for the passive films formed in the borate buffer solution. On the other hand, a negative photo current generated, the absolute value of which decreased as applied potential increased in the sulfuric acid solution. This indicates that the passive film behaves as a p-type Semiconductor. However, Mott–Schottky plot revealed the typical n-type Semiconductor Property. It is concluded that the passive film on the Fe–18Cr alloy formed in the borate buffer solution is composed of both n-type outer hydroxide and inner oxide layers. On the other hand, the passive film of the Fe–18Cr alloy in the sulphuric acid consists of p-type oxide and n-type hydroxide layers. The behaviour of passive film growth and corrosion was discussed in terms of the electronic structure in the passive film.
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Semiconductor Property of passive films and corrosion behavior of fe cr alloys
2006Co-Authors: Shinji Fujimoto, Hiroaki TsuchiyaAbstract:Knowledge of the structure and properties of oxide films of metals and alloys is important for understanding corrosion behaviour, because the protective action of most highly corrosion resistant metals and alloys essentially derives from passivity which is caused by an extremely thin oxide and/or hydroxide surface layer. Passivity of Fe-Cr alloys is one of the most important topics in corrosion science, because alloyed Cr is enriched in the passive film to act in a very important role regarding protection. Therefore, passive films on Fe-Cr alloys have been characterized by various ultrahigh vacuum (UHV) analytical techniques such as Auger electron spectroscopy (AES) and X-ray photoelectron spectroscopy (XPS). Such UHV surface characterization techniques cause specimens to be modified under quite different environmental conditions compared with those in which passive films are formed. Therefore, in situ electrochemical surface characterization techniques have been tried. The author of this work reported the photoelectrochemical response and electrochemical impedance spectroscopy of passive films on Fe-Cr alloys to reveal differences in electronic structure of passive films formed in a sulphuric acid and a borate buffer solution [1–3]. In the present chapter, the author summarizes the photoelectrochemical response of passive films on Fe-18Cr alloy comparing with the Mott-Schottky relation, which is correlated to corrosion behaviour.
Ying Li - One of the best experts on this subject based on the ideXlab platform.
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electrochemical corrosion behavior of nanocrystalline materials a review
Journal of Materials Science & Technology, 2010Co-Authors: Ying Li, Fuhui WangAbstract:Nanocrystallization significantly influences the electrochemical corrosion behaviors of metals/alloys in liquid system. In active dissolution, nanocrystallization accelerates the corrosion reactions. If the corrosion products are dissoluble, the corrosion rate is increased by nanocrystallization; if the corrosion products are insoluble, the corrosion rate is decreased on the contrary because the corrosion products act as a block layer to delay the dissolution. In passivation, nanocrystallization changes the composition of the passive film, and results into different morphology and growth process of the passive film, both of which improves the formation of compact film and influences the Semiconductor Property. It influences the passivation depending on fast element diffusion and special adsorbed ability. The small grain size improves the element diffusion, which leads to the different composition of passive film (passive elements enrichment such as Cr, Ti). The small grain size also changes the surface condition, which influences the ions adsorption. All increase the corrosion resistance of materials. In local corrosion, nanocrystallization increases the unstable points on the surface of the materials, which increases the possibility of local corrosion. However, the excellent ability of element diffusion helps heal the local corrosion points, which inhibits the growth of the local corrosion.
Dan Chen - One of the best experts on this subject based on the ideXlab platform.
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applied trace alkali metal elements for Semiconductor Property modulation of perovskite thin films
Molecules, 2019Co-Authors: Chuangchuang Chang, Jin Cheng, Tao Ling, Dan ChenAbstract:With the rapid consumption of energy, clean solar energy has become a key study and development subject, especially the when new renewable energy perovskite solar cells (PSCs) are involved. The doping method is a common means to modulate the properties of perovskite film. The main work of this paper is to incorporate trace amounts of alkali metal elements into the perovskite layer and observe the effects on the properties of the perovskite device and the majority carrier type of the perovskite film. Comparative analysis was performed by doping with Na+, K+, and Rb+ or using undoped devices in the perovskite layer. The results show that the incorporation of alkali metal ions into the perovskite layer has an important effect on the majority carrier type of the perovskite film. The majority carrier type of the undoped perovskite layer is N-type, and the majority carrier type of the perovskite layer doped with the alkali metal element is P-type. The carrier concentration of perovskite films is increased by at least two orders of magnitude after doping. That is to say, we can control the majority of the carrier type of the perovskite layer by controlling the doping subjectively. This will provide strong support for the development of future homojunction perovskite solar cells. This is of great help to improve the performance of PSC devices.
