The Experts below are selected from a list of 28935 Experts worldwide ranked by ideXlab platform
Yoshimichi Ohki - One of the best experts on this subject based on the ideXlab platform.
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plasma enhanced chemical vapor deposition and characterization of high permittivity Hafnium and zirconium silicate films
Journal of Applied Physics, 2002Co-Authors: Hiromitsu Kato, T Nango, Takeshi Miyagawa, Takahiro Katagiri, Kwang Soo Seol, Yoshimichi OhkiAbstract:Deposition of Hafnium silicate films with various Hafnium contents was tried by plasma-enhanced chemical vapor deposition using tetraethoxysilane and a Hafnium alkoxide. From x-ray photoelectron spectroscopy, the deposited films are confirmed to be silicate with Hf–O–Si bonds but without any Hf–Si bonds. The permittivity calculated from the capacitance of the accumulation layer increases monotonically with an increase in the Hafnium content, whereas the optical band gap energy estimated from vacuum ultraviolet absorption spectra decreases. Similar results were obtained from zirconium silicate films deposited using tetraethoxysilane and a zirconium alkoxide. If we compare the films with the same Hafnium or zirconium content, the Hafnium silicate exhibits a higher permittivity and a larger band gap energy than the zirconium silicate.
W U Ming - One of the best experts on this subject based on the ideXlab platform.
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Extraction Kinetics of Zirconium and Hafnium in DIBK-P204 System
Nonferrous Metals, 2013Co-Authors: W U MingAbstract:The extraction kinetics of zirconium and Hafnium in DIBK-P204 system were studied.The effects of stirring speed,interfacial area and temperature on the extraction rates of Hafnium and zirconium were investigated with constant interface cell.The results show that the extraction rates of Hafnium and zirconium in DIBK-P204 system fit with pseudo-first order reaction.The reaction types for Hafnium and zirconium extraction are reaction control within phase and mixed-control.The apparent activation energy of Hafnium and zirconium is-32.193 kJ/mol and-18.984 kJ/mol respectively.
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solvent extraction of Hafnium from thiocyanic acid medium in dibk tbp mixed system
Transactions of Nonferrous Metals Society of China, 2012Co-Authors: X U Zhigao, W U Yanke, Li Zhang, Lijun Wang, W U MingAbstract:Abstract A novel process for the separation of Hafnium from thiocyanic acid medium using the mixture of diisobutyl ketone (DIBK) and tributyl phosphate (TBP) as the extractant was developed. This extraction process was investigated experimentally as a function of the amount of TBP added, acidity, zirconium and Hafnium concentrations, salting-out agent, temperature, duration, respectively. The results show that Hafnium is enriched in the organic layer and zirconium is in aqueous layer in DIBK-TBP system. Under the optimal technological conditions: TBP addition 20% (v/v), aqueous phase acidity 3.0 mol/L, ammonium sulfate addition 0.8–1.25 mol/L, room temperature and extraction time 10 min, the separation factor of Hafnium from zirconium is 9.3.
Dong Xue-pin - One of the best experts on this subject based on the ideXlab platform.
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Research Progress on Mechanism of the Separation of Zirconium and Hafnium Extraction
Guangzhou Chemical Industry, 2015Co-Authors: Dong Xue-pinAbstract:Chemical properties of zirconium and Hafnium is very similar,the extraction of zirconium and Hafnium separation is main method. The mechanism of different solvent extraction separation of zirconium and Hafnium was reviewed,such as MIBK extracting Hafnium,( DIBK)-P204 extracting Hafnium,TBP extracting zirconium,N235-H2SO4 extracting zirconium,and the mechanism of other solvent extraction system,petroleum sulfoxide,Versatic Acid10,Cyanex301,LIX 84-IC,etc. The application of relatively mature system of extraction separation of zirconium and Hafnium in industrial were compared,and the promote industrialization direction of the extraction separation of zirconium and Hafnium were discussed as follows: the new extractant research,extraction agent modification of existing research,minimum consumption extractant,the new extraction technology of short time extraction research.
Hiromitsu Kato - One of the best experts on this subject based on the ideXlab platform.
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plasma enhanced chemical vapor deposition and characterization of high permittivity Hafnium and zirconium silicate films
Journal of Applied Physics, 2002Co-Authors: Hiromitsu Kato, T Nango, Takeshi Miyagawa, Takahiro Katagiri, Kwang Soo Seol, Yoshimichi OhkiAbstract:Deposition of Hafnium silicate films with various Hafnium contents was tried by plasma-enhanced chemical vapor deposition using tetraethoxysilane and a Hafnium alkoxide. From x-ray photoelectron spectroscopy, the deposited films are confirmed to be silicate with Hf–O–Si bonds but without any Hf–Si bonds. The permittivity calculated from the capacitance of the accumulation layer increases monotonically with an increase in the Hafnium content, whereas the optical band gap energy estimated from vacuum ultraviolet absorption spectra decreases. Similar results were obtained from zirconium silicate films deposited using tetraethoxysilane and a zirconium alkoxide. If we compare the films with the same Hafnium or zirconium content, the Hafnium silicate exhibits a higher permittivity and a larger band gap energy than the zirconium silicate.
Frédéric Villiéras - One of the best experts on this subject based on the ideXlab platform.
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Mechanically activated solid-state synthesis of Hafnium carbide and Hafnium nitride nanoparticles
Journal of Alloys and Compounds, 2008Co-Authors: Elodie Barraud, Sylvie Begin-colin, G. Le Caër, Odile Barres, Frédéric VilliérasAbstract:International audienceNanocrystalline Hafnium nitrides and Hafnium carbides are synthesized, from powder mixtures based on partially hydrated Hafnium tetrachloride, ph-HfCl4, and on magnesium, by a three-step process, namely a short mechanical activation step followed by a brief annealing step and a leaching step. Grinding of ph-HfCl4 + Mg leads to the formation of Hafnium hydrides which decompose upon annealing in argon to give first metallic Hafnium and then HfO2 at higher temperatures. Annealing of such ground ph-HfCl4 + Mg blends in flowing nitrogen yields HfN nanoparticles (average size between 10 and 30 nm). HfC carbides are directly mechanosynthesized from ph-HfCl4 + Mg + C powder mixtures. A subsequent heat treatment in flowing argon allows to better crystallize the grains of HfC (average size around 100 nm) and to decompose the intermediate products. The reaction mechanisms are discussed from results of thermogravimetric analyses and from infrared spectra of ph-HfCl4 + Mg based powder mixtures processed in various ways
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Mechanically activated solid-state synthesis of Hafnium carbide and Hafnium nitride nanoparticles
Journal of Alloys and Compounds, 2007Co-Authors: Elodie Barraud, Sylvie Begin-colin, G. Le Caër, Odile Barres, Frédéric VilliérasAbstract:Nanocrystalline Hafnium nitrides and Hafnium carbides are synthesized, from powder mixtures based on partially hydrated Hafnium tetrachloride, ph-HfCl4, and on magnesium, by a three-step process, namely a short mechanical activation step followed by a brief annealing step and a leaching step. Grinding of ph-HfCl4 + Mg leads to the formation of Hafnium hydrides which decompose upon annealing in argon to give first metallic Hafnium and then HfO2 at higher temperatures. Annealing of such ground ph-HfCl4 + Mg blends in flowing nitrogen yields HfN nanoparticles (average size between 10 and 30 nm). HfC carbides are directly mechanosynthesized from ph-HfCl4 + Mg + C powder mixtures. A subsequent heat treatment in flowing argon allows to better crystallize the grains of HfC (average size around 100 nm) and to decompose the intermediate products. The reaction mechanisms are discussed from results of thermogravimetric analyses and from infrared spectra of ph-HfCl4 + Mg based powder mixtures processed in various ways.
