Focused ion beam patterning is a powerful technique for guiding the growth of ordered hexagonal porous anodic alumina. This study shows that, with the guidance of the focused ion beam patterning, hexagonal porous anodic alumina with interpore distances from 200 to 425 nm can be fabricated at 140 V in 0.3 M phosphoric acid. When the interpore distance is increased to 500 nm, alternating diameter nanopore arrays are synthesized with the creation and growth of new small pores at the junctions of three large neighboring pores. Moreover, alternating diameter nanopore arrays in hexagonal arrangement are fabricated by focused ion beam patterning guided anodization. Interpore distance is an important parameter affecting the arrangement of alternating diameter nanopore arrays. Different types of novel patterns are obtained by designing different focused ion beam concave arrays. The fundamental understanding of the process is discussed.
A novel yet straightforward one-pot synthesis technique was developed to grow silica nanorods on the interior and exterior surfaces of a porous, inorganic scaffold. Growth of the rods on the surface, versus in the bulk, was achieved by functionalizing the surface with chlorosilane molecules, which allowed the emulsion droplets in which the nanorods grow to anchor to the surface. Rods of 100-200 nm diameter and up to 2 mm in length could be grown uniformly over the surface with a typical surface density of 3 rods per mm 2 , resulting in an order-of-magnitude increase in the specific surface area (area per mass) of the porous material. It was also shown that the properties of the rods (e.g., size, surface density, shape) could be controlled by changing either the composition of the substrate material or the concentrations of key components in the reacting mixture. Furthermore, by selectively controlling the spatial location of the chlorosilane surface groups, the rods could be grown in specific locations inside the porous material.
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