ProfessorSimon Ringer

Professor Ringer's research is about atomic-scale materials design. He uses a materials science and engineering approach to learn how small groups of atoms in special architectures-atomic clusters-can create materials with remarkable properties. New combinations of electronic, magnetic, chemical and mechanical properties are being discovered with applications in semiconductors for photovoltaics and communications, catalysis, and new lightweight metal alloys of aluminium, magnesium, titanium alloys, and advanced structural steels. He uses insights from atomic-resolution electron microscopy and atom probe microscopy to create 'designer microstructures' with special interfaces, dopant distributions, atomic clusters and nanoscale particles. As represented in the graphic below, these are the 'tools' for microstructural design.

A particular interest for Professor Ringer is in 'property conflicts'. In many instances in materials engineering, we require a profile of materials properties such that some of the properties may be in conflict with each other. Examples are strength and ductility-usually materials exhibit one, or the other-but in practice, we desire both. Other examples include superconductivity and magnetism, and semiconductivity and certain other electrical and mechanical properties can be difficult to balance. Resolving or minimising property conflicts so as to achieved balanced materials properties is a great challenge in materials design and represents an ultimate goal of the microstructural engineering that Professor Ringer and his team are researching.

Research case study: atomic-level characterisation

Professor Simon Ringer's research group has achieved a breakthrough in materials science by developing a powerful new microscopy technique that uncovers atomic-scale modifications in crystalline materials. This technique is pivotal for materials such as advanced steels andspecialised silicon, allowing for the design of high-performance materials at an atomic level.

Published in Nature Materials (IF: 37.2), this research has exposed the mechanisms behind the formation of short-range order (SRO) in CoCrNi alloys under various heat treatment conditions. By employing advanced techniques such as transmission electron microscopy (TEM) and atom probe tomography (APT), the team has provided unparalleled insights into the atomic arrangements that enhance the mechanical properties of these alloys. This research not only advances our understanding of material properties but also opens up new possibilities for material design and application in criticalindustries, such as aerospace, energy, manufacturing, and biomedical.

Link to paper in Nature Materials, and USyd news artlcle.

Research case study: advanced steels

Professor Ringer's team are at the forefront of the design and development of so-called third-generation advanced high strength steels. They have created novel steel chemistries and novel thermomechanical processing routes that achieve extraordinary mechanical properties. The innovation is truly significant. Reducing the weight of a car by 100 kg reduce CO2 emissions by about six grams per kilometre driven, and fuel usage by about half a litre of fuel per 100 km. Extrapolated globally, the potential impact would be gigatonnes of CO2 emissions, gigalitres of fuel and vast amounts of particulates that are not released into the atmosphere. The health implications around light-weighting are also enormous. Some of the work was recently summarised in MRS Bulletin. Basically, the team have achieved controlled partitioning of manganese across austenite-ferrite phase interfaces so as to 'prime' the austenite with just the right amount of metastability as to render is prone to both transformation induced plasticity and twin induced plasticity mechanisms. Professor Ringer's team are leaders in the science of atom probe microscopy and the insights gained from this technique have been a critical enabler for this research on advanced steels

Research case study: new approaches to computer memory

As published recently in Physical Review Letters, Professor Ringer and his team have used a finely focused beam of electrons rastered across a special ceramic material, to pave the way towards a new paradigm for increasing the memory capacity of computer hard drives.

Responding to consumer demand for increased computer hard drive memory, the research also has the potential to reduce the environmental footprint of the more than 2.5 billion hard drives currently estimated to be in use worldwide.

If you lined up all the world's hard drives back-to-back, they would go around the globe 5 times, and hard drives are partly manufactured from non-biodegradable aluminium and other metals. This project focussed on the materials science for memory storage. In some oxide ceramics called ferroelectric materials, there exist tiny domains that can that contain an electric dipole that is switchable. Two opposite dipole directions can be used as the two logic signals '0' and '1', so that they can serve as memory bits. The key challenge is how to 'set' the domains to one condition or the other, and how to 'switch' the domains once written. Conventional techniques use local heating, mechanical stress or electrical bias-all of which have major drawbacks. Zibin Chen (PhD student) and Professor Liao (Sydney) discovered that a high-energy electron beam with an omni-directional electric field does the job!

This approach could reduce the current memory domain size by 100 times, resulting in a 100 times greater data storage capability.

Professor Ringer explains: "As materials engineers, we think a lot about how to stimulate local changes in the atomic-scale structure of materials so as to access remarkable new properties and behaviour. We are really excited to have discovered that applying these local electric fields with nanoscale precision can create a new paradigm for computer memory."

Research case study: nanoelectronics

Professor Ringer's team are driving the design and development of nanowires forward, with new insights to improve the efficient and cost-effective production of these building blocks of nanoelectronics. Ternary InGaAs nanowires made from Indium (In), Gallium (Ga) and Arsenic (As) from the III-V group of the periodic table are highly 'tunable' in terms of their electron properties such as band gap. For example, we can dope them with particular elements in the growth stage to change electrical properties, or change the growth conditions to vary their shape or size. Their semiconducting properties make them attractive for applications in optoelectronics, thermoelectrics, and photovoltaics. The team's work is focussed on controlling the growth and properties of the semiconductor nanowires, which are regarded as the next generation building blocks for the future of electronics. As part of a longstanding successful collaboration with colleagues at ANU, Professor Ringer and colleagues (A/Prof. Rongkun Zheng in Physics and Ph.D. student, Jiangtao Qu) are unlocking mechanisms of how the vapour-liquid-solid (VLS) mechanism for fabricating nanowires actually works. Professor Ringer, says: " These unprecedented 3D insights into the nanowires enable deeper understanding of nanowire growth and the growth-structure-property relationships." "This a marvellous scientific achievement that places Sydney uniquely at the forefront of III-V semiconductor nanowire design and development. These materials will be driving all sorts of nanoelectronics technology into the future." This work was published in Advanced Materials in 2017.

Academic Leadership

Professor Ringer leads the Core Research Facilities program and as such leads the strategic planning and implementation of the program. His team are working to ensure that Sydney's peak research infrastructure is truly world-class. This effort contributes to the University's capacity to achieve our strategic plan 2016-2020 because research infrastructure is a prime determinant of our ability to undertake world-leading research. The way that we choose to respond to the most significant challenges of our time, around climate, health, food, water, energy, communications, transport, manufacturing, construction and national security will largely define our future as an institution.