Kinetic study on preparation of substoichiometric tungsten oxide WO2.72 via hydrogen reduction process

2018 ◽  
Vol 137 (2) ◽  
pp. 389-397 ◽  
Author(s):  
Dan Qiao ◽  
Yue Wang ◽  
Fan Li ◽  
Daya Wang ◽  
Baijun Yan
Keyword(s):  
Kinetic Study ◽  
Tungsten Oxide ◽  
Hydrogen Reduction ◽  
Reduction Process

Refining mechanisms of arsenic in the hydrogen reduction process of tungsten oxide

2015 ◽  
Vol 26 (3) ◽  
pp. 1013-1020 ◽  
Author(s):  
Hongbo Zhu ◽  
Dunqiang Tan ◽  
Yalei Li ◽  
Xin Yang ◽  
Wen He
Keyword(s):  
Tungsten Oxide ◽  
Hydrogen Reduction ◽  
Reduction Process

scholarly journals Evolution of reduction process from tungsten oxide to ultrafine tungsten powder via hydrogen

2021 ◽  
Vol 40 (1) ◽  
pp. 171-177
Author(s):  
Yue Wang ◽  
Ben Fu Long ◽  
Chun Yu Liu ◽  
Gao An Lin
Keyword(s):  
Surface Morphology ◽  
Tungsten Oxide ◽  
Tungsten Powder ◽  
Reduction Process ◽  
Chemical Vapor ◽  
Transition Process ◽  
Vapor Transport ◽  
Fibrous Structure ◽  
Chemical Vapor Transport ◽  
Oxide Particles

Abstract Herein, the evolution of reduction process of ultrafine tungsten powder in industrial conditions was investigated. The transition process of morphology and composition was examined via SEM, XRD, and calcination experiments. The results show that the reduction sequence of WO2.9 was WO2.9 → WO2.72 → WO2 → W on the surface, but WO2.9 → WO2 → W inside the oxide particles. With the aid of chemical vapor transport of WO x (OH) y , surface morphology transformed into rod-like, star-shaped cracking, floret, irregularly fibrous structure, and finally, spherical tungsten particles.

Copper Chemical Vapor Deposition using a Novel Cu(II) Precursor for Contact Via Filling Process

2007 ◽  
Vol 990 ◽  
Author(s):  
Hideaki Zama ◽  
Yuuji Nishimura ◽  
Michiyo Yago ◽  
Mikio Watanabe
Keyword(s):  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
Hydrogen Reduction ◽  
Reduction Process ◽  
Chemical Vapor ◽  
Molar Ratio ◽  
Cu Films ◽  
Pure Cu ◽  
Substrate Temperatures ◽  
Advanced Generation

ABSTRACTChemical vapor deposition (CVD) of copper using both a novel Cu(II) β-diketonate source and hydrogen reduction process was studied to fill contact vias with the smallest diameter in the 32nm and more advanced generation chip. Pure Cu films were grown under the condition with the product of hydrogen partial pressure and H2/Cu source molar ratio being over 1,000,000. We succeeded in filling the 40-nm-diameter contact vias by optimizing the growth condition of the Cu-CVD in both substrate temperatures and reaction pressures.

TGA kinetic study on the hydrogen reduction of an iron nickel oxide

2013 ◽  
Vol 54 ◽  
pp. 32-38 ◽  
Author(s):  
Dawei Yu ◽  
Mingqian Zhu ◽  
Torstein A. Utigard ◽  
Mansoor Barati
Keyword(s):  
Nickel Oxide ◽  
Kinetic Study ◽  
Hydrogen Reduction ◽  
Iron Nickel

Kinetics of synthesizing process for obtaining iron nanopowder by chemical-metallurgical method under isothermal conditions

2021 ◽  
pp. 72-77
Author(s):  
Tien Hiep Nguyen ◽  
◽  
Van Minh Nguyen ◽  
Keyword(s):  
Hydrogen Reduction ◽  
Average Particle Size ◽  
Chemical Deposition ◽  
Reduction Process ◽  
Nitrogen Adsorption ◽  
Specific Rate ◽  
Average Particle ◽  
Isothermal Conditions ◽  
Electron Microscopes ◽  
Kinetics Of

In this work the kinetics of synthesizing process of metallic iron nanopowder by hydrogen reduction from α-FeOOH hydroxide under isothermal conditions were studied. α-FeOOH nanopowder was prepared in advance by chemical deposition from aqueous solutions of iron nitrate Fe(NO3)3 (10 wt. %) and alkali NaOH (10 wt. %) at room temperature, pH = 11, under the condition of continuous stirring. The hydrogen reduction process of α-FeOOH nanopowder under isothermal conditions was carried out in a tube furnace in the temperature range from 390 to 470 °C. The study of the crystal structure and composition of the powders was performed by X-ray phase analysis. The specific surface area S of the samples was measured using BET method by low-temperature nitrogen adsorption. The average particle size D of powders was determined via the measured S value. The size characteristics and morphology of the particles were investigated by transmission and scanning electron microscopes. The calculation of the kinetic parameters of the hydrogen reduction process of α-FeOOH under isothermal conditions was carried out by the Gray-Weddington model and Arrhenius equation. It is shown that the rate constant of reduction at 470 °C is approximately 2.2 times higher than in the case at 390 °C. The effective activation energy of synthesizing process of iron nanopowder by hydrogen reduction from α-FeOOH was ~38 kJ/mol, which indicates a mixed reaction mode. In this case, the kinetics overall process is limited by both the kinetics of the chemical reaction and the kinetics of diffusion, respectively, an expedient way to accelerate the process by increasing the temperature or eliminate the diffusion layer of the reduction product by intensive mixing. It is show that Fe nanoparticles obtained by hydrogen reduction of its hydroxide at 410 °C, corresponding to the maximum specific rate of the reduction process, are mainly irregular in shape, evenly distributed, the size of which ranges from several dozens to 100 nm with an average value of 75 nm.

scholarly journals A Novel Process for the Synthesis of NaV2O5 Mesocrystals from Alkaline-Stripped Vanadium Solution via the Hydrothermal Hydrogen Reduction Method

Minerals ◽  
2019 ◽  
Vol 9 (5) ◽  
pp. 271
Author(s):  
Guobin Zhang ◽  
Yimin Zhang ◽  
Shenxu Bao ◽  
Liuhong Zhang
Keyword(s):  
Electron Microscopy ◽  
Hydrogen Reduction ◽  
Ph Value ◽  
Hydrothermal Process ◽  
Reduction Process ◽  
Oriented Attachment ◽  
Synthesis Process ◽  
Synthesis Mechanism ◽  
Time Saving ◽  
Synthesis Time

NaV2O5 mesocrystals were successfully synthesized from an alkaline-stripped pentavalent vanadium solution through a novel hydrothermal hydrogen reduction process. The optimal conditions for the hydrogen partial pressure, reaction temperature, initial solution pH value, and reaction time for the pure-phase NaV2O5 synthesis were ascertained to be 4 MPa, 200 °C, 4.0, and 2 h, respectively. The synthesis time (only 2 h) was greatly shortened, by nine times, compared with the most time-saving (18 h) hydrothermal process at present. X-ray diffraction (XRD) analysis revealed that the as-prepared powders demonstrated a typical layered orthorhombic structure of NaV2O5. The purity of the as-prepared NaV2O5 reached up to 99.98%. An electrochemical test showed that the as-prepared NaV2O5 has a potential application in sodium ion batteries. According to scanning electron microscopy (SEM) and transmission electron microscopy (TEM) analyses, the as-prepared NaV2O5 powders were identified to have rod-like mesocrystals consisting of small rods which preferentially grow along the (010) direction. Furthermore, the phase transformation mechanism and crystal growth mechanism in NaV2O5 preparation were discussed systematically, based on which the synthesis mechanism of NaV2O5 was proposed as pentavalent vanadates pre-sedimentation, hydrogen reduction with dehydration, sodium ions insertion, and finally self-assembly oriented attachment. The synthesis process is characterized as time-saving and low-cost, and thus it may have great application prospects.

Nucleation of Tungsten on Titanium Nitride with Hydrogen Reduction of Tungsten Hexafluoride

1992 ◽  
Vol 282 ◽  
Author(s):  
D. Srinivas ◽  
R. Foster ◽  
S. Marcus ◽  
R. Arora ◽  
H. Rebenne
Keyword(s):  
Titanium Nitride ◽  
Nucleation Rate ◽  
Incubation Time ◽  
Seed Layer ◽  
Total Pressure ◽  
Hydrogen Reduction ◽  
Reduction Process ◽  
Tungsten Hexafluoride ◽  
Short Incubation Time ◽  
Competing Reactions

ABSTRACTIn this work, a hydrogen (H2) reduction process has been developed which gives tungsten (W) nucleation on titanium nitride (TiN) adhesion layers with a very short incubation time, eliminating the need for a silane (SiH4reduced seed layer. The nucleation was found to be strongly dependent on the following factors: temperature of the substrate, total pressure in chamber, and gas introduction sequence into the reactor. Theenhanced nucleation rate has been explained based on two competing reactions: dissociation of H2, and formation of titanium subfluorides on the TiN surface.

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