Why The NANO Conference?
Nanoscience and nanotechnology is one of the fastest growing research area. The birth of modern nanoscience can be dated back to 1959 when Richard Feynman at Cal Tech spoke of“Plenty of Room at the bottom” to highlight the tremendous scientific and technological potential of materials and devices at atomic/molecular dimensions. About twenty years later, Herbert Gleiter demonstrated the benefits for mechanical properties of ultrafine grains in solids and named them “nanostructured solid”. His theoretical investigation had immediate practical relevance for particle-hardening of metals in specific applications such as turbines and jet engines and pushed research activity toward the development of new nanostructured materials, with different properties.
Nanostructured materials can be classified in different groups, according to their “nano” properties:
The oldest group goes back to the days of the old Egyptians and Chinese 2000 BC. This group comprises the effects that are called today size-effects. If the size of solids is reduced to dimensions comparable to interatomic spacings, certain properties may change in comparison to the bulk material. Already the people in ancient Egypt knew that certain glasses became red when certain minerals were added. In fact, they knew that mixing Au minerals in a glass results in this effect. Even about 1000 years before the this development in Egypt, the Chinese knew that grinding mercury-oxide for a long time changes its color. Faraday was the most well known person that studied these effects in modern times. And modern solid state physics provided detailed explanations.
The second group are surface effects of nm-sized materials. The most important sub-group exploiting surface effects are the catalysts. They were known and studied by the turn of the last century e.g. by H.E. Fischer when he was awarded the Nobel Prize for this work. Recently in medicine new methods of diagnostics and therapy based on nm-clusters with specially designd surfaces are becoming important.
The third group are solids of macroscopic size with a nm-sized microstructure. Here the two most important sectors are the precipitation hardened alloys and the GMR effect. Precipitation hardening was discovered by Wilm around 1920 and is it related to dislocation motion. The GMR was worked out by Grünberg and Fert about 10 years ago and it is related to the transport of electrons in SC or metals.
The next group are solids with new atomic and electronic structures due to the fact that they contain up to 50% grain or interphase boundaries in which atoms are positioned dfferently from crystals or glasses. They were called nanocrystalline materials and they were produced initially by consolidating nm-sized crystallites of identical or different chemical compositions. This development is about 30 years old. If one of the components of a nanocrystalline material is an electrolyte, then about 50% of the atoms are located at the
crystal/electrolyte interfaces and if the crystals are electric conductors and we apply a voltage between them and the electrolyte, we get a Helmhotz double layer at these interfaces which allows us to tune the electronic structure (and hence all the electronic structure related properties) of the
nanocrystalline material. This development is about 25 years old.
Now, most recently the latest member of the family are glasses into which defects on a nanometer scale are introduced. The basically new and unexpected effect is that these nanoglasses are not just similar to nanocrystalline materials but they open the way to a whole new world of non-crystalline
solids with atomic and electronic structures different from glasses. In fact, it seems that they permit that we can produce to any microstructure we know today in crystalline materials the analogous microstructure in glasses by means of nanoglasses. If that were so, we should be able to built a new world of technologies based on these new glasses similar to the technology world of today based mostly (metals, SC, ceramics) on crstalline materials (Provided somebody finds a way to produce nanoglasses economically.)The nanoglasses teach us that glasses are just one form of non-crystalline solids. And by introducing these interfaces, new noncrystalline states of solid matter are
formed with dramatically new properties such as a ferromagnetic non-crystalline FeSc solid whereas the FeSc glass is paramagnetic.