Template synthesis of nanomaterials

Abstract

Abstract. We present an overview of template synthesis as it applies to our nanomaterials research. This bottom-up approach is motivated by our desire to find an alternative to the big, top-down approaches to nanoscience, such as clean-rooms and X-ray lithography. Using universally available templates and materials, and very modest synthesis techniques, we have created a variety of interesting and useful structures. Starting with homogeneous ferromagnetic nanowires, we were able to study and manipulate spin-dependent transport. Next, we branched into multi-layer GMR and spin-valve structures for spintronics. As a side trip, we put carbon-encapsulated fullerene nanoparticles into nanopores for ballistic magnetoresistance studies. Carbon nanotube molecules were grown in templates by CVD self assembly. The carbon nanotubes grown using a cobalt catalyzer show spin-valve, ballistic transport, and Coulomb blockade effects. Very recently, we have started to study templated semiconductor nanorods with the amazing result that their behaviour is very similar to that of the carbon nanotubes and can be reduced to a scaling law. Essentially, the template acts as a skeleton for the nanoscale synthesis and macroscale contact of an infinite variety of materials and structures. It is our hope that by the following examples we demonstrate that high quality nanoscience research is available to everybody. PACS

Carbon nanotubes prepared by anodic aluminum oxide template method

“…By selecting anodizing voltage at different electrolytes during the anodizing process, AAO films with different pore sizes can be obtained. For example, H 3 PO 4 , C 2 H 2 O 4 , and H 2 SO 4 electrolytes produce AAO films with pore sizes of 150-300 nm, 30-70 nm, and below 20 nm, respectively [68,77]. Now, AAO films with a uniform and adjustable channel sizes of 20-200 nm can be reproducibly synthesized [78].…”

“…The CNTs synthesized by this way have same outer diameter and tunable wall thickness and inner diameter (as shown in Figure 6). Since the outer diameter of AAO-CNTs can be as large as 300 nm [68,77], their inner diameter can be tuned in a wide range of several nm to nearly 300 nm. The other approach is to select AAO films with different channel sizes as template.…”

Template electrosynthesis of La(OH)3 and Nd(OH)3 nanowires using porous anodic alumina membranes

“…Template-directed synthesis [13] utilizing anodic alumina membrane (AAM) [14][15][16][17] has become a popular pathway to produce nanometric-size materials [18] of different nature (metals, semi-conductors, polymers and oxides), and for different applications. The successful use of AAMs in this field is related to: (a) easy and low-cost fabrication method, (b) benefits of a high pore densities in a hexagonal highly ordered close-packed arrays [19,20], (c) ability to tailor pore diameters and depths by simply controlling the anodizing conditions of aluminium [21][22][23][24][25].…”

Fabrication and Applications of Metal Nanowire Arrays Electrodeposited in Ordered Porous Templates

“…Today, such ordered porous films are widely employed as mass fabrication tools, i.e. 'templates', for a myriad of 1D and composite nanomaterials in the name of fundamental and/or technological interests [Martin, (1994); Wade & Wegrowe, (2005)]. The template synthetic method is so versatile [Hurst et al, 2006;Das, B.…”