Professor David McKenzie - Research Highlights

Research Career Summary - Professor Marcela M.M. Bilek

Marcela Bilek has applied her problem solving skills and knowledge of the physical sciences to a broad range of problems in science, industry and the wider community. Over the past decade, since graduating with a B.Sc. (Hons) and University Medal from the University of Sydney in 1991, she has contributed in a variety of areas including theoretical computer simulation at the atomic scale, laboratory studies of processing plasmas, thin film materials and surface modification. Her interests are linked by an underlying theme - the desire to apply her knowledge to problems of significance in the "real world", and to transfer the technologies conceived in universities to industry where they can be used to the benefit of society.

After her graduation in 1991, Marcela began working as an industrial research scientist for an Australian aluminium smelting company. During her two and half years on the job she developed a 3D computer model [45,46] based on the finite difference method, to simulate the complex two-phase flow processes in an aluminium reduction cell. The model calculated the stirring effects of the carbon dioxide bubbles escaping from under carbon anodes immersed in cryolite, as well as liquid metal induced flows generated by the magnetic fields that result from the high electric currents consumed in the reduction process. Accurate simulations of these mixing flows for different configurations of anodes inside and current carrying bus bars outside the cell, allows the identification of designs which produce the most efficient mixing patterns while maintaining low erosion on the walls. Since each test cell costs millions of dollars to construct, huge savings are achieved by doing the bulk of the experimentation on a computer. The model was internationally recognised by the award of the 1993 Minerals, Metals and Materials Society Reduction Technology Prize.

Upon completion of this project, Marcela won Peterhouse College and Cambridge Commonwealth Trust scholarships at the University of Cambridge, U.K., to study for a PhD. Her project involved the development of a new plasma technology for the fabrication of thin film materials [37-44] After submitting her thesis she was awarded an Emmanuel College Research Fellowship. During the Fellowship she worked on the development of plasma based technologies [15-36] which form the basis of modern techniques used to synthesise the specialised materials required for applications in microelectronics, optics, machining and biomaterials. While based in the UK (1993-1999) much of her research was done in collaboration with groups in Australia and the USA. Her work on amorphous silicon thin films was recognised by the award of the Bunshah medal at the International Conference on Metallurgical Coatings and Thin Films in San Diego in 1997.

In the course of her experimental work on plasma processes she successfully developed a model [31] to predict the transport of cathodic arc plasmas through magnetic filters and a fast, accurate experimental technique [34] to measure plasma beam spatial density profiles. The model is the first to be able to predict cross-sectional profiles of plasma beams as a function of magnetic field configuration. The measurement technique is now being used in many research laboratories as a diagnostic to determine spatial density distributions in condensable plasma reactors. Using her model of filter transport together with the results of experimental studies performed using the new measurement technique, Marcela was able to devise a design methodology [25] for building plasma macroparticle filters with homogeneous beam profiles required for six inch wafer based microelectronics manufacturing facilities. This work led to a provisional patent^* for a deposition and plasma filtering process for use in the coating of hard disks and read-write heads.

Marcela has modelled the effects at the atomic scale, which control the growth of thin films produced by plasma deposition processes. Her model [22] of hydrogenated amorphous carbon, based on a quantum mechanical treatment of the electrons involved in chemical bonding, predicts accurately measurable physical properties, such as the position of infra-red absorption peaks and neutron diffraction spectra. The good agreement with measurable signatures such as these indicates that the structures accurately represent the microstructures of the real materials. Recently Marcela has developed a similar model for the hydrogenated silicon carbide system, which is important because of its application to photovoltaic cells. This model also shows good agreement with experimental signatures and provides important new insights [1] into the strained bonding environments of amorphous ternary alloys [10] A new technique to study chemical bonding in amorphous solids has been developed and used to identify various defects and delocalised bonds present in a-SiC:H materials and to study their temperature dependence. The breaking and reformation of strained bonds in amorphous solids at thermal temperatures has been observed for the first time. The development of models of this type holds the promise of fast efficient design of advanced materials [7] with properties tailored specifically to applications. Together with a colleague at the University of Sydney, Marcela developed a thermodynamic framework for understanding the development of preferred crystallographic orientations in materials grown with energetic ions [6,16,27,35] She wrote a computer code based on the model which calculates the preferred orientations favoured under different growth regimes and predicts the experimental electron diffraction patterns observed [27]

In 1999 she became Guest Professor at the University of Hamburg-Harburg, Germany, where she developed an undergraduate degree program in General Engineering Science. In June 2000 she completed a US MBA program with a perfect score. Marcela returned to Australia in November 2000 to become Professor of Applied Physics at the University of Sydney. During her time in this position she has attracted around $3M in research funding and developed concepts leading to 3 new provisional patents. In March 2001 she co-convened a multidisciplinary conference on the use of the RF spectrum and possible biological effects of microwave radiation. It was a first in the area and attracted wide spread media publicity. This event was instrumental in disseminating information to the community and bringing together stakeholders from all sides of the debate and has led to productive new research alliances between members of the telecommunications industry and academia. In April 2000 she gave a public lecture in the Sydney Science Forum series on the topic of the RF spectrum and on the 17th of May she gave the 14th memorial Pollock lecture for the Royal Society of NSW on the topic of biomaterials and surface modification for improving the functionality of materials. She has recently been awarded an Australian Institute of Political Science 2001 Young Tall Poppy Award for outstanding young researchers and the 2002 Malcolm McIntosh Prize for Physical Scientist of the Year.

Professor Bilek's current research projects range from the design and creation of super-tough coatings for biomedical applications to the development of highly insulating window glazing to the interactions of surfaces and electromagnetic fields with bio-molecules.

In her recent research on surface coatings Professor Bilek has developed a plasma process [2,5,9,12,14] for improving the properties of coatings so that they perform at the highest level. This level of performance is needed for biomedical applications of coated components where adhesion, wear-resistance and biocompatibility must be exceptional. The key step in the process was the release of the stress in the coating during growth by regular impacts of the surface with high-energy ions [19,12] This work has resulted in a number of invitations to present at international meetings including a plenary session at the International Symposium on Discharges and Electrical insulation in Vacuum (ISDEIV) 2002 in Tours, France. Coatings fabricated using the new process are currently being evaluated by an Australian biomedical company for use in an implantable heart pump.