Alumina interfaces

A three-stage adsorption isotherm is obtained for tetradecyltrimethylam-monium chloride (TTAC) [130] at the alumina interface at pH 10 (Fig. 37). At... 

Detailed HRTEM characterization of the specimens showed that all metal-ceramic interfaces in the two different nanocomposites had thin ( 1 nm thick) amorphous films (see Fig. 11.5). In addition, occluded particles were found inside the alumina grains which also had thin amorphous films at their interfaces with alumina. Analytical microscopy showed the films to contain Ca, Si, and Al.41 Hamaker coefficients were calculated for metal-ceramic interfaces in the presence of a Si02-based film, which indicated that a stronger attractive force is expected for intergranular films at metal-alumina interfaces,... 

The initial reaction step involves the deposition of carbon and silica, as shown experimentally by Lin et al.14 In their work, they examined the reaction front separating the reaction product from the unreacted composite using transmission electron microscopy (TEM). During the initial stages of reaction, graphitic carbon and silica glass were formed at the SiC-alumina interface, as... 

The small number of charge carriers in the semiconductor is partially compensated for by the small size of metal particles. By using Schwab s magnetic measurements as a clue to the number of electrons transferred to the nickel across the nickel-alumina interface it can be estimated that a change of 0.05 electron per atom would produce detectable catalytic effects. By extrapolation to the small dispersed type of metal particle being considered here, it is seen that for a particle containing 2000 atoms the equivalent transfer would be produced by 100 electrons. Despite this, if one considers contact between a 2000-atom platinum particle and a 100 alumina particle (volume 4 x 10 cc) the flow of electrons to the metal would be drastically limited by the small number of charge... 

Considering that under reaction conditions identical to those stated just above the Pd(l 11) single-crystal surface remained metallic, palladium nanoparticles are apparently easier to oxidize than bulk palladium, possibly because of the higher abundance of surface defects. The palladium oxide phase may be located not only on the particle surface but also at the palladium/alumina interface (515). Partial oxidation of palladium particles has been observed previously for combustion reactions on technological catalysts and may lead to complex hysteresis phenomena (see Refs (514,516) and references therein). 

Anodic oxidation of aluminum opens another way to production SPM tip characterizers. Namely it is known that aluminum/anodic alumina interface has an appropriate geometry for this purpose. On the other hand aluminum is a plastic material that may be damaged during scanning. Our results show that despite of proposed mechanical instability anodized aluminum surface is excellent tip characterizer that may be used for a long time. 

Fig. 4.18. Procednre to make Pt particles separated from Pt dots by an alnmina interface (1) Adsorption of 530-nm PS particles on top of a Pt film on an alumina film, (2) melting of PS colloids to hemispheres, (3) Ar+ etching through the Pt film to the alumina layer, (4) further melting of the PS hemispheres, (5) deposition of a ceria layer, and finally, (6) liftoff of the PS spheres by a combination of a hot acetone bath and O2 plasma. The SEM image shows a 540-nm Pt particle surrounded by ceria with a thin separating alumina interface (from [91])...

Vakros J. et al.. Adsorption of cobalt ions on the electrolytic solution/y-alumina interface studied by diffuse reflectance spectroscopy (DRS), Langmuir, 20, 10542, 2004. 

The CTacks on the composite solid electrolyte-alumina interface usually appear when the composite solid electrolyte is rapidly quenching after the fusing temperature, which is normally over 1850°C, down to the temperature around 70Q-1000°C. Consequently, to avoid cracking, more gradual cooling should be provided around the whole interface area by various techniques. As a result, the... 

Until recently, the extent of pH modification could only be inferred indirectly. Measurements have become available using the second harmonic generation technique. For the aqueous solution/silica interface, they yielded pH variations between bulk and surface of -0.6 (at pHbuik = 6) or -2.3 (at pHbulk= 12) the effect is expected to be more important for the aqueous solution/ alumina interface, since the extent of surface charging is higher for alumina. 

Libera [99] has presented an alternative for the study of polymer morphology avoiding the staining procedure as a way to induce amplitude contrast. EEe proposed the use of EELS to study different polymer systems to obtain several levels of resolution (related to the radiation sensitivity of the material) when studying interfaces, such as those in polystyrene-poly(2-vinyl pyridine) homopolymer blends, epoxy-alumina interfaces, and hydrated polymers. Polymers could be distinguished from each other on the basis of the energy-loss spectra in their low loss (valence) and core loss (elemental composition). 

Fig. 11 (a) Two slabs of alumina separated by a collection of aldehydes. Shear stress is imposed by moving the upper slab a distance. Ax, relative to the lower slab, (b) A hydroxylated alumina interface contained within a simulation cell. Compression can be achieved by subjecting the system to a stress (L) or strain (e ) perpendicular to the interface. Shear can be achieved by applying a shear stress (t) or a shear strain (e z) parallel to the interface... 

R.D. ARMSTRONG, W.l. ARCITER, The double layer capacity of the Au/Na-b-alumina interface-variation with temperature , J. Electroanal. Chem., 87, 221-224, 1978. 

Smialek has summarized the sulfur effect [10], which is generally explained in terms of the sulfur segregating to the alloy/oxide interface and lowering the work of adhesion. Sulfijr has been shown to lower the fracture energy of artificial Ni/alumina interfaces from F 100 J/m to r w 10 J/m [11]- A question remains regarding the mechanism of the... 

By adding an element into the liquid metal, it is possible to decrease both (Ts and a. The adsorption of the element at the solid-liquid interface generally improves both the adhesion and the wetting. On the contrary, its adsorption at the free liquid surface always destroys the adhesion. It improves the wetting only for 0 angles lower than 90°. These features have been checked on Al-Sn alloy-alumina interfaces (Eustathopoulos and Drevet, 1994). 

Vogt, Bryan D., Prabhu, Vivek M., Soles, Christopher L., Satija, Sushil K., Lin, Eric K., Wen-li, Wu Control of moisture at buried polymer/alumina interfaces through substrate surface modification. Langmuir 21, 2460 (2005)... 

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