Narrow Results

High aspect ratio inorganic structures with at least one dimension between 1 and 100 nm, such as nanotubes, nanowires, and nanorods, have attracted a keen interest both for fundamental research and for advanced applications because of their unique and fascinating properties, largely contributing to the rise of nanoscience as a new discipline of scientific progress worldwide. Although the synthesis of high aspect ratio nanostructures has been achieved through many different strategies, the exact mechanisms that lead to their formation are not clear and need to be elucidated to control the properties and reliability of these nanoscopic “building blocks”. Here I give few examples of growth methods based on chemical and physical processes, and I describe the results of the first characterization of the nanostructures by high-resolution electron microscopy techniques. The analysis of surfaces and interfaces, epitaxial relationships, and defects is expected to advance the understanding of the growth strategies and of the properties at the nanoscale. Far from being a complete review, this report is meant to show the achievements and the difficulties of experimental research in nanoscience, and to introduce the challenges that lay ahead.

With the benefit of millions of years of natural selection, it is no surprise that when it comes to fitting form to function, Nature is second to none in engineering the right structure for the right job. The creation of architectural elegance, despite using the minimal amount of material has long fascinated man, who has endeavored to understand how intricate construction can be accomplished merely through the flow of inorganic ions and strategically placed macromolecules. When the demands of the environment are the blueprints of the construction, structures are produced with the utmost efficiency. This was first stated explicitly by D'Arcy Thompson, in his seminal work On Growth and Form (1917).¹ However, even as far back as the 16th century, scientist and astronomer Johannes Kepler noted that “Nature uses as little as possible of anything”. Both these and many other luminaries held Nature in the highest esteem as an engineer par excellence.

In the 19th century, people used these tenets and took their inspiration for daring and innovative architectural and engineering projects from Nature. In the 21st century therefore, when advanced nanoscale materials are required, it is only right that man should once again turn to Nature for solutions to their creation.