29 June 2005
A Monash team has developed a "stroboscopic diffraction" technique that could lead to improved infra-red detectors similar to those used on the Mars probe to produce images of the Martian surface.
Associate Professor Trevor Finlayson and PhD researcher Mr John Daniels from the School of Physics developed the technique in collaboration with Dr Andrew Studer from the Australian Nuclear Science and Technology Organisation (ANSTO) and Dr Mark Hagen (formerly of ANSTO and now at Brookhaven National Laboratory in the US). They are using it on a material called triglycine sulphate, a relative of the material used in the Mars probe.
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| PhD researcher Mr John Daniels with Associate Professor Trevor Finlayson. |
Dr Finlayson said triglycine sulphate was interesting because of how its structure changed when maintained at about 49 degrees Celsius and exposed to an electric field, temperature variations or stress. "This temperature is triglycine sulphate's phase transition temperature, above and below which its electrical properties change dramatically," Dr Finlayson said.
"We are interested in changes in the material's physical properties so need to understand the nature of the phase change. For example, we want to know the structure of a triglycine sulphate crystal above and below the temperature at which the phase change takes place, how the change takes place and whether it is reversible."
Understanding the nature of the phase transition in triglycine sulphate could improve future infra-red detectors, Mr Daniels said.
A change in the material's structure is determined by directing neutrons at the material and looking at how they scatter as they pass through.
"We use neutrons to look at the structure of triglycine sulphate crystals because they can penetrate deep into the material," Mr Daniels said.
He is studying the material's phase transition at ANSTO using the stroboscopic scattering technique. Mr Daniels spent 12 months building high-voltage circuits and programming software in developing the technique.
"The stroboscopic technique allows you to watch the phase transition as time progresses and to learn about kinetics rather than just knowing that the phase changes. It allows you to see what happens during the transition," he said.
The technique is not only applicable to tryglycine sulphate studies. It could also be used to study phase transitions in other materials.
Shortly after the technique was developed, Mr. Daniels was approached by a colleague from the University of New South Wales to undertake collaborative research on another interesting material, lead zirconium titanate. This material has wide applications in piezoelectric devices, which convert electrical energy to mechanical energy and vice-versa.
Mr Daniels' research towards his PhD is supported by an Australian Postgraduate Scholarship and an Australian Institute of Nuclear Science and Engineering Postgraduate Award. | 
