The Optimum Preparation of WC-Co Composite Powders by Sol-Gel and Hydrogen Reduction

2014 ◽  
pp. 229-236
Author(s):  
Wang Xiaoyan ◽  
Huang Liling ◽  
Zhang Zhengfu ◽  
Peng Jinhui ◽  
Hou Hongying
Keyword(s):  
Hydrogen Reduction ◽  
Sol Gel ◽  
Composite Powders

The Optimum Preparation of WC-Co Composite Powders by Sol-Gel and Hydrogen Reduction

2014 ◽  
pp. 229-236
Author(s):  
Wang Xiaoyan ◽  
Huang Liling ◽  
Zhang Zhengfu ◽  
Peng Jinhui ◽  
Hou Hongying
Keyword(s):  
Hydrogen Reduction ◽  
Sol Gel ◽  
Composite Powders

ChemInform Abstract: Synthesis of High-Tc Dual-Phase Ag-YBa2Cu3O7-x Superconductor Composite Powders by Sol-Gel Process.

ChemInform ◽  
2010 ◽  
Vol 23 (40) ◽  
pp. no-no
Author(s):  
M. K. AGARWALA ◽  
D. L. BOURELL ◽  
C. PERSAD
Keyword(s):  
Sol Gel ◽  
Dual Phase ◽  
Composite Powders ◽  
High Tc ◽  
Sol Gel Process

SURFACE-CHARGE-ENABLED PHOTOLYTIC HYDROGEN GENERATION IN V2O5·H2O/Au NANOCONJUGATES

MRS Advances ◽  
2016 ◽  
Vol 1 (46) ◽  
pp. 3121-3126
Author(s):  
Sunith Varghese ◽  
Charuksha Walgama ◽  
Mark Wilkins ◽  
Sadagopan Krishnan ◽  
Kaan Kalkan
Keyword(s):  
Surface Charge ◽  
Hydrogen Generation ◽  
Hydrogen Reduction ◽  
Energy Levels ◽  
Sol Gel ◽  
Band Edge ◽  
Conduction Band Edge ◽  
Current Voltage ◽  
Negative Surface ◽  
Negative Surface Charge

ABSTRACTThe present work investigates sol-gel synthesized vanadium oxyhydrate (V2O5·H2O) nanowires decorated with Au nanoparticles as potential photolytic H2 generators. As determined by UV photoelectron and optical spectroscopies, the conduction band edge of V2O5·H2O lies 0.6 eV below standard H+ reduction potential, implying no H2 can be generated. On the contrary, as measured by gas chromatography, our nanoconjugates yield reproducible light-to-hydrogen conversion efficiency of 5.3%, for the first hour of photolysis under 470 nm excitation. To explain the observed hydrogen reduction, we have hypothesized the vanadia electron energy levels are raised by some negative surface charge. With the objective of validating this hypothesis, we have performed cyclic current-voltage measurements. The derived conduction and valence band edge energies are not only consistent with the optical band gaps, but also validate the hypothesized energy increase by 1.6 eV, respectively. The negative surface charge is also corroborated by the ζ-potential. Based on the measured pH of 2.4, we attribute the negative surface charge to Lewis acid nature of the nanowires, establishing dative bonding with OH−. The present work establishes the importance of surface charge in photoelectrochemical reactions, where it can be instrumental and enabling in photolytic fuel production.

scholarly journals BaGeO3 as sintering additive for BaTiO3-MgFe2O4 composite ceramics

2019 ◽  
Author(s):  
Roberto Köferstein
Keyword(s):  
Magnetic Measurements ◽  
Sol Gel ◽  
Dissipation Factor ◽  
Composite Ceramics ◽  
Composite Powders ◽  
One Pot ◽  
Fine Grained ◽  
Sintering Additive ◽  
Nano Crystalline ◽  
Sintering Behaviour

BaTiO3-MgFe2O4 composites (30 wt.% MgFe2O4) with a small addition of BaGeO3 as a sintering additive were synthesized by a one-pot Pechini-like sol-gel process. Nano-crystalline composite powders with a crystallite size of about 10 nm were obtained after reaction at 700 °C for 1 h. Magnetic investigations suggest that the nano-powder is in its superparamagnetic state at room temperature. The addition of BaGeO3 leads to an improved sintering behaviour. DTA measurements reveal the formation of a liquid phase at 1164(3) °C. Dense ceramic bodies (relative density > 90 %) were obtained after sintering for 1 h at 1150 °C. SEM investigations prove a 0-3 connectivity and show that the addition of BaGeO3 promotes the grain growth leading to particles up to 4 μm. In contrast, fine-grained composite ceramics with smaller particles up to 230 nm were obtained after a two-step sintering process. Magnetic measurements indicate a ferrimagnetic behaviour with coercivity values up to 70 Oe depending on the sintering procedure. Furthermore, addition of BaGeO3 results in an increase of the relative permittivity, whereas the dissipation factor slightly decreases.

Synthesis of High-Tc Dual-Phase Ag-YBa2Cu3O7-x Superconductor Composite Powders by Sol-Gel Process

1992 ◽  
Vol 75 (7) ◽  
pp. 1975-1977 ◽  
Author(s):  
Mukesh K. Agarwala ◽  
David L. Bourell ◽  
Chadee Persad
Keyword(s):  
Sol Gel ◽  
Dual Phase ◽  
Composite Powders ◽  
High Tc ◽  
Sol Gel Process

Synthesis and magnetic properties of Fe/SiO2 nanocomposites prepared by a sol–gel method combined with hydrogen reduction

2006 ◽  
Vol 419 (1-2) ◽  
pp. 145-148 ◽  
Author(s):  
N.J. Tang ◽  
H.Y. Jiang ◽  
W. Zhong ◽  
X.L. Wu ◽  
W.Q. Zou ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Hydrogen Reduction ◽  
Sol Gel ◽  
Gel Method ◽  
Sol Gel Method ◽  
Sio2 Nanocomposites

Characterization of Zirconia Sizing Nozzle Modifying Addictives Preparated by Sol-Gel Method

2014 ◽  
Vol 1078 ◽  
pp. 31-35
Author(s):  
Liang Zhao ◽  
Qun Hu Xue ◽  
Dong Hai Ding
Keyword(s):  
Heat Treatment ◽  
Particle Size ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Heat Treatment Temperature ◽  
Sol Gel ◽  
Treatment Temperature ◽  
Composite Powders ◽  
Gel Method ◽  
X Ray

MgO-Al2O3-ZrO2composite powders with 3 kinds of mass ratio were synthesized by sol–gel method using MgCl2·6H2O, AlCl3·6H2O and ZrOCl2·8H2O as starting materials, and NH3·H2O as a precipitant. The composite powders which match with zirconium oxide particle size and evenly distribute can are advantageous to the formation of metastable t-ZrO2and restrain the grain growth as the additive of modified sizing nozzle. Chemical composition, mineral phase, particle size distribution and micro-morphology of the composite powders were investigated by X-ray fluorescence instrument, X-ray diffractometer, laser particle size analyzer and scanning electron microscope. Research showed that under the process that the concentration of MgCl2solution 0.2 mol/L, AlCl3and ZrOCl2solution concentration 0.5 mol/L, the pH controlled between 10 ~ 11, PEG as the surfactant, drying at 70°C±5°C, heat treatment temperature at 800°C for 3h, particle size distribution of MgO-Al2O3-ZrO2composite powders were: d10= 1.28 μm, d50= 4.65μm, d90= 11.13μm (MgO 10%); d10= 1.15μm, d50= 5.80μm, d90= 15.13μm (MgO 15%);d10= 1.21μm, d50= 6.59μm, d90= 16.87μm (MgO 20%). With the rising of heat treatment temperature, the crystallization degree of composite powders increased, at 800 °C a small amount of t - ZrO2precipitated, meanwhile MgO and Al2O3are still in the amorphous phase. The MgO-A12O3-ZrO2composite powders under this condition have high reactivity and uniform distribution.

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