Alumina templates anodic

Fig. 2. SEM images of the top surfaces of porous anodic alumina templates anodized in (a) 4 wt% H2C2O4 and (b) 20 wt% H2SO4. The average pore diameters in (a) and (b) are 44 nm and 18 nm, respectively.

Alumina templates anodic, 169-170 processing anodic films, 170 scanning electron microscopy (SEM) of porous, 171 schematic, 170... 

Metal oxide nanotubes have been synthesized by a diverse variety of fabrication routes. For example titania nanotubes, and nanotube arrays, have been produced by deposition into a nanoporous alumina template [48-51], sol-gel transcription using organo-gelators as templates [52,53], seeded growth [54], hydrothermal processes [55-57] and anodic oxidation [58-65]. 

Figure 6(a) shows a SEM image of bismuth nanowires embedded in an anodic alumina template after pressure injection. The pore diameter of the template was about 42 nm, and the maximum pressure and temperature applied for the injection process were about 310 bar and 325°C, respectively. A small amount of copper was introduced into hquid bismuth to enhance its injection the copper atoms should be segregated from bismuth during solidification because they have zero solubihty in solid bismuth. Upon solidification, the copper flakes were brought to the top surface of Bi due to their... 

Fig. 6. (a) SEM image of the bottom surface of an anodic alumina template filled with bismuth. The pore diameter is 42 nm. (b) TEM micrograph of the cross section of a 65-nm bismuth nanowire array (Zhang et al., 1999). 

The smallest diameter attained for bismuth nanowires by the pressure injection method was about 13 nm, using a pressure of approximately 0.3 kbar (Zhang et al., 1999). Finer nanowires might be fabricated by increasing injection pressures (Huber et al., 2000), but it remains to be seen if the anodic alumina templates would retain their structural integrity under those high pressures. 

Tantalum hydride on Si02, supported metal complexes, 62 Template-assisted synthesis anodic alumina templates, 169-170 description, 169... 

Mesoporous alumina membranes ( anodic aluminium oxide , or AAO) are prepared by anodic oxidation of aluminium metal [1,2]. The cylindrical pores, perpendicular to the membrane surface, form hexagonal arrays of straight non-intersecting channels with pore densities up to lO Vcm. Their diameters are controllable within the range 5 - 100 nm as a linear function of anodisation voltage. These membranes are used as molecular sieves, and have also found application as templates for metallic nanowires [3,4,5,6], metal elusters and colloids [7,8], and carbon nanotubes [9,10]. 

Since metallic Sn has a high capacity for reversible Li insertion, pure Sn as well as its intermetallic compounds have been considered as promising anode materials in lithium ion batteries. In intermetallic compounds of Sn, the second metal is normally electrochemically inactive and cannot be alloyed with Li. Such an inactive metal performs as a buffer to accommodate volume variations during Li insertion/deinsertion in Sn.224 Among various Sn intermetallic compounds, Ni3Sn4232-235 and CU6S115236 237 are the most commonly studied materials. Intermetallic compounds of Sn with Ni and Cu can be electrochemically deposited. Templates are conventionally used to improve the morphological properties and, thus, the electrochemical behavior of the electrodeposited Sn and Sn intermetallic compounds. Copper nanopillars can be electrodeposited within alumina templates on a Cu foil to provide a unique template for the subsequent electrodeposition of Sn or its intermetallic compounds. 

Anodic porous alumina is conventionally grown on aluminum foils, as indicated in Fig. 2. Similar self-assembled growth is achieved on Si by depositing an A1 thin film on the front side of a silicon wafer and forming an ohmic contact on the back side that is used as anode. The electrochemical solutions currently used are oxalic or sulfuric acid aqueous solutions. Details for the fabrication of thin alumina templates on Si with adjustable pore size and density are given elsewhere [8]. Electrochemical oxidation of A1 starts from the A1 surface and continues down to the Al/Si interface, following an anodization current density/time curve as shown in Fig. 3. 

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