Preparation of Monodispersed Spherical Silica-Alumina Particles by Hydrolysis of Mixed Alkoxides

1994 ◽  
Vol 165 (1) ◽  
pp. 141-147 ◽  
Author(s):  
Shuichi Nishikawa ◽  
Egon Matijević
Keyword(s):  
Spherical Silica ◽  
Alumina Particles ◽  
Silica Alumina ◽  
Hydrolysis Of

Mn-doped CsPbCl3 perovskite quantum dots (PQDs) incorporated into silica/alumina particles used for WLEDs

2018 ◽  
Vol 448 ◽  
pp. 400-406 ◽  
Author(s):  
Meiling He ◽  
Yinzi Cheng ◽  
Lingli Shen ◽  
Chenyang Shen ◽  
Huiling Zhang ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Alumina Particles ◽  
Perovskite Quantum Dots ◽  
Silica Alumina ◽  
Mn Doped

Electrical properties of silica-alumina ceramics in nitrogen atmosphere

1993 ◽  
Vol 8 (5) ◽  
pp. 1116-1121 ◽  
Author(s):  
Yoshihiro Hirata ◽  
Mitsunori Kawabata ◽  
Yoshimi Ishihara
Keyword(s):  
Bridge Circuit ◽  
Nitrogen Atmosphere ◽  
Alumina Ceramics ◽  
Reduced Pressure ◽  
Oxygen Ions ◽  
Electronic Conductivities ◽  
Electrical Conductivities ◽  
Silica Alumina ◽  
Hydrolysis Of Metal Alkoxides ◽  
Hydrolysis Of

The SiO2–Al2O3 powders with compositions of 46.5 to 76.6 wt. % Al2O3, synthesized by the hydrolysis of metal alkoxides, were sintered at 1700 °C for 3 h in a reduced pressure of 40 Pa. After sintering, the samples were annealed at 1300 °C for 10 h in air. The densities of sintered samples were higher than 97.0% T.D. The electrical conductivities of the SiO2–Al2O3 ceramics in N2 atmosphere (>99.99%) were measured in the temperature range of 500° to 800 °C by using ac bridge circuit at 120 Hz to 1 MHz and dc circuit at 1 V. The electrical conductivities at 800 °C were 3.4 × 10−7 to 4.3 × 10−6 S cm−1, and decreased with increasing Al2O3 content. The SiO2–Al2O3 ceramics were mixed conductors of oxygen ions and electrons in nitrogen atmosphere. The activation energies of ionic and electronic conductivities were 102 to 143 kJ/mole and 102 to 123 kJ/mole, respectively.

The influence of the pore structure of hollow silica–alumina composite spheres on their activity for hydrolytic dehydrogenation of ammonia borane

2017 ◽  
Vol 4 (9) ◽  
pp. 1568-1574 ◽  
Author(s):  
Tetsuo Umegaki ◽  
Ryota Ogawa ◽  
Naoki Toyama ◽  
Shinobu Ohki ◽  
Masataka Tansho ◽  
...  
Keyword(s):  
Pore Structure ◽  
High Activity ◽  
Ammonia Borane ◽  
Hollow Silica ◽  
Silica Alumina ◽  
Alumina Composite ◽  
Hydrolysis Of

Hollow silica–alumina composite spheres with a homogeneous pore structure showed unexpected high activity for hydrolysis of ammonia borane.

Speciation in Size and Density Fractionated Fly Ash III. The influence of HCL Leaching on the Glassy Constituents of a High-Ca Fly Ash

1987 ◽  
Vol 113 ◽  
Author(s):  
E. E. Berry ◽  
R. T. Hemmings ◽  
B. J. Cornelius
Keyword(s):  
Fly Ash ◽  
Ion Exchange ◽  
Hollow Spheres ◽  
Acid Attack ◽  
Density Fractions ◽  
Alumina Gel ◽  
Silica Alumina ◽  
Hydrolysis Of

ABSTRACTAsh density fractions, separated from a high-Ca fly ash, were leached with 6M HCl at 105°C. The density fractions (<0.79 and >2.85 g.cm−3) selected for leaching have been shown in previous work to consist largely of two different glass types, designated Glass I and Glass II. It was shown that both Glass I and Glass II are leachable to yield solutions containing Al and modifier cations. Acid attack on Glass I appears to involve hydrolysis of Si–O–Al (silalane) bridges along with ion exchange at available non-bridging oxygen sites. Attack on Glass II is more extensive, with both silalane and siloxane bridges being hydrolysed, and ion-exchange occurring at non-bridging oxygens. The products of leaching are aluminosilicates. In the case of Glass I, these remain as pseudomorphic, hollow spheres; whereas, for Glass II, substantial reprecipitation of silica (alumina) gel was found.

Electrical Characterization of Slurry Particles and their Interactions with Wafer Surfaces

1999 ◽  
Vol 566 ◽  
Author(s):  
Jin-Goo Park ◽  
Sang-Ho Lee ◽  
Hyoung-Gyun Kim
Keyword(s):  
Particle Deposition ◽  
Colloidal Silica ◽  
Electrical Characterization ◽  
Dlvo Theory ◽  
Silica Particles ◽  
Zeta Potentials ◽  
Alumina Particles ◽  
Silica Alumina ◽  
Wafer Surfaces

The purpose of this study was to explore the interaction between slurry particles and wafer surfaces by the measurements of their zeta potentials. The zeta potentials of slurry particles such as fumed and colloidal silica, alumina, ceria and MnO2 and substrates such as silicon, TEOS, W, and Al have been measured by electrophoretic and electroosmosis method to evaluate the electrical properties of surfaces, respectively. The zeta potential of oxide and metal surfaces showed similar values to those of particles as a function of pH. The interaction energy between alumina and silica particles and TEOS, W and Al substrate were calculated based on DLVO theory. No deposition of silica particles on TEOS and the heavy deposition of alumina particles on metal substrates were observed in the particle deposition test. Experimental results were well agreed with the theoretical calculation.

The kinetics of deuterium-neopentane exchange: effects of desorption and diffusion

1968 ◽  
Vol 302 (1469) ◽  
pp. 253-270 ◽  
Keyword(s):  
Product Distribution ◽  
Single Step ◽  
Surface Exchange ◽  
Product Distributions ◽  
Exchange Effects ◽  
Alumina Particles ◽  
Silica Alumina ◽  
Rate Processes ◽  
Kinetics Of ◽  
And Diffusion

The product distribution of isomers from the deuterium exchange of neopentane over palladium supported on silica-alumina particles is influenced by the competition among three rate processes: desorption, diffusion, and surface exchange. The theory based on a single-step surface mechanism is presented and given quantitative treatment, suitable for large conversions. The experimental results show a very wide variety of product distributions over the same catalyst, and can be quantitatively correlated by the theory.

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