Faculty of Natural and Agricultural Sciences
School of Physical Sciences
Department of Physics
Selected Highlights from Research Findings
Carbon exhibits a variety of interesting structural and electronic systems because of its propensity to form both sp2 and sp3 bonds. This gives rise to a range of interesting magnetic, transportation and physical properties for carbon and carbon-based materials – especially nanoscaled materials – with a wide range of both established and potentially new applications involving a multitude of structural systems such as nanotubes, graphite, buckeyballs and, lately, graphene.
Prof Nithaya Chetty of the Department of Physics is engaged in a research programme involving the theoretical and computational studies of carbon and carbon-based materials. His research expertise is in the field of the theoretical and computational studies of solid-state systems within the framework of density functional theory, which is a quantum mechanical method to study the electronic properties of solids. Today, with the advent of modern, faster computers with larger memories, and also with the development of faster computational algorithms to solve the relevant equations more efficiently, calculations can be performed locally and cheaply, rather than having to rely on massive supercomputers, which was the case a decade ago. This, together with faster networking and the availability of open source and freeware software has made the field of computational studies of materials a fast-developing research activity in South Africa, and a burgeoning field at the University of Pretoria.
The advent of graphene in 2004 has excited much interest in these unique two-dimensional systems because of the enormous potential that graphene has for novel applications. These systems also provide theoreticians with the opportunity to explore novel methods for modelling them because of their ideal two-dimensional nature. Graphene, which may be considered to be a single layer of graphite, is a semi-metal with a unique electronic structure. The low-energy electronic excitations are massless, which results in ballistic electronic transport. A great effort recently has been centred on altering the electronic structure of graphene using various dopants. This research, together with the work of master’s student Edwin Mapasha, involves studies of lithium on graphene. The attachment of lithium on this material holds promise for lithium energy storage devices. Li on graphene has been studied by several previous authors, and the researcher is extending this study to newer configurations to give more detailed structural and electronic results that have not been previously considered. He is also testing the results against different approximations to the exchange-correlation potential, which is an essential construct in his computations.
Together with PhD student Richard Andrew and Prof Max Braun of the Faculty of Education, he is exploring the elastic properties of alloys of carbon with silicon. Alloys of these elements only appear to exist at 1:1 mixing, low concentrations of impurities of C in Si, or low concentrations of Si in C. It appears that higher levels of doping are not possible, or have not yet been realised in the laboratory. This research project entails exploring the crystalline stability and physical and electronic properties of alloys involving C with Si that cover the entire range of alloy mixing, and focuses on predicting the properties of these systems. The great advantage of being able to do computational “experiments” is that one has the ability to consider material systems that have not been realised experimentally before and, in so doing, one has the technology to predict the properties of systems that are yet to be discovered.
Contact person: Prof N Chetty.
Sub-Antarctic Marion Island is located in the Southern Indian Ocean, approximately halfway between South Africa and Antarctica. The island was first discovered in 1663 and annexed by South Africa in 1947. Since then, South Africa maintains a permanent weather and research station on the island. Recently scientists from the Department of Physics analysed the volcanic rocks on Marion Island using Raman spectroscopy. Hematite (red iron oxide) was identified as the colouring agent responsible for the red colour of the scoriae cones that can be seen from space. Hematite was also identified as a thin layer that covers glassy phases in the volcanic rock. This hematite appears grey and supports studies proposing volcanic activity as an alternative mechanism for grey hematite formation on Mars.
Contact person: Dr LC Prinsloo.
Sub-Antarctic Marion Island is located in the Southern Indian Ocean, approximately halfway between South Africa and Antarctica. The island was first discovered in 1663 and annexed by South Africa in 1947. Since then, South Africa maintains a permanent weather and research station on the island. Recently scientists from the Department of Physics analysed the volcanic rocks on Marion Island using Raman spectroscopy. Hematite (red iron oxide) was identified as the colouring agent responsible for the red colour of the scoriae cones that can be seen from space. Hematite was also identified as a thin layer that covers glassy phases in the volcanic rock. This hematite appears grey and supports studies proposing volcanic activity as an alternative mechanism for grey hematite formation on Mars.
Contact person: Prof DJ Brink.
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