In this major feature, Curve editor, Belinda Stening, caught up with materials scientist, Associate Professor Simon Ringer, Executive Director & CEO of the Nano-structural Analysis Network Organisation (NANO) Major National Research Facility (MNRF) and Director of the Australian Key Centre for Microscopy and Microanalysis at the University of Sydney.
According to Professor Ringer, nanotechnology involves building functional structures using individual atoms and molecules as the building blocks: these new ‘nanomaterials’ feature specific properties as a result of the controlled manipulation of matter.
“In nanotechnolgy you can start with nothing and add molecules and atoms to build materials from the ‘bottom up’.”
“Areas such as electron microscopy, atom probe tomography, x-ray tomography and other modes of light and laser-optical modes of imaging provide our ‘gateway to discovery’ of the nanoworld: designing structures on the nanoscale, or one-millionth of a millimetre, is throwing up many exciting new challenges for engineers and scientists working in nanotechnology.”
Ringer says a major driving force influencing materials development worldwide is the trend towards atomic or molecular control of structure-function relationships. However, as Ringer notes, “nanotechnology is not just miniaturisation or microtechnology”.
The observation made in 1965 by Gordon Moore, co-founder of Intel Corporation, that the number of transistors per square inch on integrated circuits had doubled every year since the integrated circuit was invented presents what appears to be one of several inexorable forces driving innovation and ‘bottom-up’ nanotechnology.
Another exciting development is that engineers are designing structures that work on the same length scales as the molecular building blocks of life: proteins, nucleic aids, lipids and carbohydrates exhibit characteristics defined by their nanoscale size and symmetry.
Ringer and his colleagues are designing materials using building blocks of individual atoms or clusters of atoms to adjust the physical and biological properties of matter to suit specific applications.
For example, light alloys are seen as important to Australia’s economic future because of the country’s abundant mineral reserves in aluminium, titanium and magnesium.
“With the new instrumentation that NANO is developing such as an ‘advanced atom probe’, we are starting to see nanoscale clusters of atoms that form rapidly within these materials,” Ringer explained.
“As a result we are starting to think about what those atomic clusters will do to change the material properties and to direct subsequent phase transformations during the processing and fabrication of these light alloys.”
According to Ringer, individual co-clusters have a big influence on the properties, such as the strength of a material.
“In these and in other materials systems, we are seeing major changes in the hardening, magnetic, electronic and optical properties as a result of the formation of these tiny atomic clusters.
“This is a fresh area for research in materials and materials design methodologies and comes about from new approaches in imaging science which, figuratively, allows researchers to get under the ‘waterline’ to see below the ‘tip of the iceberg’... we know that there is much more information about a material that can be seen with atom probe tomography.”
Polymer nanocomposites are fertile areas for new materials design: “Think about fibreglass...” Ringer says, illustrating his descriptions. “We know it’s plastic and it’s got glass fibre inside of it. We know that glass is pretty hard and strong and we know that the polymer is very flexible and that when joined we make a composite of the two properties in the one material.”
More recently NANO has been working on new classes of polymer nanocomposites: materials consisting of nanoscale inorganic fillers dispersed in an organic polymer matrix. They have superior strength and stiffness, good fire retardant and barrier properties.
As such, they have found many potential applications in the automotive and packaging industries. “We are putting clay type materials into the plastic. These clays may be naturally occurring and are attractive to Australian companies interested in developing these materials for value added applications.”
Australia is a leader in the design and prototyping of optical fibre and photonic materials. Photonics, broadly speaking, describe the interaction of light with matter. These materials introduce a new paradigm for the design of communication systems, which are different to our familiar notion of copper wires and the silicon chip.
“There are lots of things going on with the design of optical fibre materials. Although optical fibre has been around for a long time, it is important to realise that people are still actively designing new types of fibres with different chemistries and fibre construction.”
Optical fibre is ultimately the medium of the information ‘superhighway’ and the challenge of getting more bandwidth is, in many respects, the challenge of understanding and exploiting nanoscale gradients in chemistry and structure in these materials and systems.
Ringer and his colleagues at NANO use the enabling technology of microscopy to record and understand images of these materials in order to interpret the structure-property relationships.
The enabling technology of microscopy and nano-structural analysis allows us to ultimately see the individual atoms in the material, Ringer explains.
“A current challenge relates to how we handle all this data: we are in the truly digital age of microscopy, recording multi-gigabit data images in three dimensions and movies recorded over time (four dimensions) and the approaches to reconstruction and extracting the information we need for design is difficult.
“For example, we are gearing up to look at a tomographic data cubes containing 100 million atoms and selecting which atom to atom interactions are delivering the functional properties of the material.
"This is a kind of ‘atomistic informatics’: we calculate the atom positions and determine their effects on properties.”
NANO has just won a large contract with a major Australian raw mineral products company to help the industry to solve some problems with export products.
“This particular group needed to know the ‘inside story’ of a very basic export commodity. Staff are using x-ray tomography to perform what is very similar to a catscan of these materials to inform industry about the quality and reactivity of these materials.”