Porous aluminum oxide

A sodium-sulfur cell is one of the more startling batteries (Fig. 12.23). It has liquid reactants (sodium and sulfur) and a solid electrolyte (a porous aluminum oxide ceramic) it must operate at a temperature of about 320°C and it is highly dangerous in case of breakage. Because sodium has a low density, these cells have a very high specific energy. Their most common application is to power electric... 

Xu D, Chen D, Xu Y, Shi X, Guo G, Gui L, Tang Y (2000) Preparation of II-VI group semiconductor nanowire arrays by dc electrochemical deposition in porous aluminum oxide templates. Pure Appl Chem 72 127-135... 

Porous aluminum oxide can be used as a template for the production of nanowires and nanotubes. For example, metals can be deposited on the pore walls by the following procedures deposition from the gas phase, precipitation from solution by electrochemical reduction or with chemical reducing agents, or by pyrolysis of substances that have previously been introduced into the pores. Wires are obtained when the pore diameters are 25 nm, and tubes from larger pores the walls of the tubes can be as thin as 3 nm. For example, nanowires and nanotubes of nickel, cobalt, copper or silver can be made by electrochemical deposition. Finally, the aluminum oxide template can be removed by dissolution with a base. 

Konno, M., M. Shindo, S. Sugawara and S. Saito. 1988. A composite palladium and porous aluminum oxide membrane for hydrogen gas separation, J. Membr, Sci. 37 193-97. 

Aluminum Oxide Moisture Sensor. This type of sensor is a capacitor, formed by depositing a layer of porous aluminum oxide onto a conductive substrate, and then coaling the oxide with a thin film of gold The conductive base and the gold layer become the capacitor s electrodes. Water vapor penetrates the gold layer and is absorbed by the porous oxidation layer The number of water molecules absorbed determines the electrical impedance of the capacity, which is. m turn, a measure of water vapor pressure. 

Davydov, D. N., Sattari, P. A., AlMawlawi, D., Osika, A., and Haslett, T. L., Field emitters based on porous aluminum oxide templates. J. Appl. Phys 86, 3983 (1999). 

G. Zangari and D. N. Lambeth, Porous Aluminum Oxide Templates for Nanometer-Size Cobalt Arrays", IEEE Trans. Magn. 33, 3010 (1997). 

Technological features of nanoprofiling of silicon protected by a solid mask made of porous aluminum oxide are considered. It is shown that the method based on bombarding structures with accelerated neutral atoms (in particular, argon atoms) is efficient for etching through this mask. 

In Fig. 1, we show the AFM image of the surface of the solid mask of porous aluminum oxide before the dry etching of the structure. The surface... 

Figure 1, AFM image of the surface of the solid mask of porous aluminum oxide.

The template method for synthesizing nanostructures involves the synthesis of the desired material within the pores of a nanoporous membrane or other solid. This approach has been used in several experiments [224—229] for the preparation of Ti02 nanotubes and nanorods typically, porous aluminum oxide (PAO) nano-templates were used. 

Figure P-8 TEM images of mesoporous silica nanorods synthesized by the 2D confinement of spherical micelles using different sizes of the porous aluminum oxide template (a) 25 nm, (b) 60 nm, and (c) 90 nm. (From A. Thomas et al. J. Mater. Chem. 2007, 17, 4558. Reproduced by permission of the Royal Society of Chemistry.)...

Similar to the formation of porous aluminum oxide a passivation - dissolution mechanism can be used to form nanopo-rous structures on InP. If (OOl)n-InP is polarized anodically under illumination in HCl solutions, nanoscaled pores are formed [117]. For potentials up to 1.2 V vs. SGE the main reaction is uniform anodic dissolution. Above this potential porous InP with a surface oxide is formed. The overpotential and anodizing time influence pore diameter (110-250 nm), wall thickness (16-50 nm) and pore length... 

Relatively bioinert ceramics maintain their physical and mechanical properties while in the host. They resist corrosion and wear and have aU the properties listed for bioceramics in Table 39.1. Examples of relatively bioinert ceramics are dense and porous aluminum oxides, zirconia ceramics, and single phase calcium aluminates (Table 39.2). Relatively bioinert ceramics are typically used as structural-support... 

SEM view of microstructured aluminum surface (a) hexagonal, (b) triangular, and (c) porous aluminum oxide with hexagonal features [21]. 

Microporous metal membranes by electrochemical etching Aluminum metal, for example, is electrochemical ly etched to form a porous aluminum oxide film. Membranes are brittle but uniform, with small pore size 0.02-2.0 fim 49,50... 

As shown in Table 16.2.1, the pore diameter is proportional to the DC potential or the current density used. The thickness of the porous aluminum oxide inaeases linearly with... 

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