The EMC provides materials expertise through the training, servicing and support of researchers involved in undergraduate, postgraduate, industrial and government research projects.
Based on their unique areas of specialised expertise, the EMC staff undertake research projects in applied microscopy via a combination of individual work, collaboration with industry/organisation partners or through the co-supervision of students.
EMC projects for HDR students
The EMC provides its users with the materials characterisation results needed for their research projects. The following research projects will be conducted by EMC-affiliated HDR students with EMC staff as their supervisors.
For more information please contact the EMC staff.
Applications of high performance structural and chemical characterisation using aberration corrected STEM
Dr David Mitchell
The newly commissioned, state-of-the-art JEOL ARM200F transmission electron microscope (TEM) is one of only two of its kind in the country. It features a range of advanced detectors for scanning mode (STEM) which greatly extend its capabilities over conventional STEM instruments. These include a backscattered electron/secondary electron detector, a large area x-ray detector, a Quantum imaging filter for energy loss and an annular bright field detector. The advanced microanalysis capabilities enable imaging and compositional/bonding information to be obtained at the atomic scale. This project will involve the experimental characterisation of advanced nanomaterials, to understand their microstructure, composition and bonding.
Correlative microscopy: Optimising the conditions for transmission diffraction in a scanning electron microscope
Dr Azdiar Gazder, Dr David Mitchell, Professor Elena Pereloma
Transmission Kikuchi Diffraction (TKD) is very new and exciting experimental methodology that has the capacity to provide orientation information at nanometer-scale resolution. This project will focus on understanding how to optimise the TKD technique as a function of the scanning electron microscope hardware and its set-up. Monte Carlo Potts modelling will be used to simulate the interaction between a sample and the electron beam in order to optimise a given experimental set-up. The quality of data obtained from various sample preparation techniques will be compared and correlated with those obtained from conventional transmission electron microscopy.
Applications of hollow cone and rocking beam illumination to TEM of Crystalline Materials
Dr David Mitchell, Dr Azdiar Gazder
One of the principal contrast mechanisms in transmission electron microscopy (TEM) is diffraction contrast, arising from Bragg scattering of electrons by crystalline materials. This contrast is however, problematic in chemical mapping, tomography, energy loss and energy dispersive microanalysis. Strong dynamical diffraction results in channelling of the beam through the crystal, producing anomalous results in spectroscopy and extinctions in tomography. Rocking beam and hollow cone illumination can help overcome this, by systematically tilting the beam about its azimuth. This project will investigate experimental conditions which help eliminate this contrast and test its validity and application. Conventionally produced single crystal and dual phase materials will be examined using the EMC?s two TEMs, which include a state-of-the-art JEOL ARM200F aberration corrected TEM/STEM, one of only two in the country.
Electron Tomography in the TEM
Dr David Mitchell, Professor Elena Pereloma
Transmission electron microscopy (TEM) is a powerful technique for characterising materials up to the atomic scale. However, TEM images are 2D projections of a 3D specimen, and 3D information is absent from a single image. Tomography is a technique which allows full 3D reconstruction of the original object from a series of images at various tilts. This project will use a state-of-the-art aberration corrected JEOL ARM200F TEM/STEM, one of only two corrected microscopes in the country. It will entail the set up and commissioning of tomography software for acquisition and reconstruction. The technique will be used to understand the 3D structure of materials, such as precipitation within Ni- 30%Fe-Nb-C alloys.
TEM imaging without magnetic fields
Dr David Mitchell, Professor Elena Pereloma
Transmission electron microscopy (TEM) uses high energy beams of electrons to image materials at up to the atomic scale. The magnetic lenses used to focus the beam generate Tesla-scale fields at the specimen. This is problematic for ferromagnetic materials ? such as steels as the specimen deflects and distorts the beam. This makes microscopy challenging. It also saturates any magnetic domains in the material, making the imaging of magnetic structure impossible. The installation of a Lorentz imaging capability on the JEOL 2011 TEM permits imaging in a field-free regime. This project will explore the application of this technique to the study the microstructure of steels in both field- and field-free modes, to understand the effectiveness and limitations of the technique.
Absolute energy determination of electron energy loss edges
Dr David Mitchell
Energy loss spectroscopy is a transmission electron microscopy (TEM)-based technique which characterises the energy lost by a high energy beam of electrons as it passes through the specimen. The resulting spectrum contains characteristic core loss edges arising from beam interactions with specific elements. The energy of these edges is element-specific but is also shifted due to the chemical bonding environment. Chemical shifts of up to 10eV can occur making it a potentially useful diagnostic tool for differentiating similar materials in different bonding environments. However, in TEM the energy scale is not fixed, but varies as the microscope voltage (HT) drifts (>10eV per hour). This project will make use of the JEOL ARM200F, a state-of-the-art, aberration corrected TEM. It will involve the development of software to interface with the energy loss spectrometer, to obtain zero loss and core loss spectra in very rapid succession, thus eliminating the effect of HT drift. The tool will be applied to the characterisation of a range of materials, such as carbon nano-materials, multiphase ceramics, nanocomposites etc to map bonding and chemical changes at the nanometre scale.