A Material World

John Kennedy is the father of two daughters, aged nine and five, and because I am ringing on the weekend, their cheerful voices can be heard throughout our conversation.
“I told them I had an appointment, but they still want me to play with them,” he says, laughing. Kennedy moved to New Zealand in 2001, and has “been working with ion beam physics, from day one.” The fundamental theory of ion beam physics was developed by New Zealand born Lord Ernest Rutherford nearly a century ago, in 1910, when he was investigating the scattering of α–rays, so Kennedy feels that it is fitting that he is doing his research here. “One of the reasons I decided to stay is that I liked he people, the country is good, and there is not so much scientific politics around, compared to other countries. And GNS is a great organisation.” John leads the core GNS Science programme on ion beam applications. And there are a lot of applications, ranging from biological, geological, environmental to advanced materials. “I’m developing new materials for sensor applications using ion beams,”he says. “I’ve been developing some new types of material for the last couple of years. I’ve found one which is a nano-magnetic material which tends
to give unique properties for detecting differences in magnetic fields.” So what is an ion beam and how can it create new materials?
 Ion beams are charged particle beams that shoot ions at a target. All sorts of ions can be used, although, for safety reasons, GNS does not use radioactive ions. The ion beams are used to bombard materials with foreign atoms, changing the surface of the material. “When you put alien atoms inside a material, sometimes they don’t like the existing atoms, so they’ll start changing their orientation and their arrangement,” says Kennedy. As the atoms start to rearrange themselves, they tend to change their symmetry with the atoms in the material. By doing that, a new band forms. “This tends to make a thin layer of new material which is a combination of the existing material and the bombarded elements. So that’s how we make these new magnetic materials,” says Kennedy. So far Kennedy has created magnetic materials using elements such as iron, cobalt and samarium and bombarded materials like silica, which act as insulators, with these foreign atoms. Once the silica has been bombarded, then a thermal treatment is applied. “This forms nucleation or bubbles, a particular structure at the surface. So for example, if I bombard the silica with iron, they tend to form iron nanoparticles with a size range of 1 to 50 nanometres,” says Kennedy. Iron is a magnetic material, and the fabricated iron nanoparticles are on
the surface, so they can be used as sensors. “When we take these magnetic nanoparticles and apply a voltage, or a current, and then expose them to
 a magnetic field , any difference in resistance is indicative of whether there are any changes in the magnetic field,” says Kennedy. “If you move that sensor, you can see differences between ferrous objects and non-ferrous al objects.” Some of the questions that Kennedy’s research will answer include how these nanoparticles form, how they grow, and what their interaction is with each other. Kennedy and his team are working with New Zealand industry on various projects, but he can’t tell me more. “That’s confidential,” he says. What he can say is that his research is helping New Zealand companies to enhance their product performance and expand their product base. “We are engaged with some of them to enable transfer of our scientific understanding and research,” says Kennedy. If these partnerships are successful,
it could open up a whole new export sector for New Zealand. “Innovation is the introduction of a new, significantly improved, product, process or method, which can increase the productivity of firms and thus the economy as a whole,” says Kennedy. “Our research on new materials is important for New Zealand because it underpins state-of-the-art technology, and goes hand in hand with the desire of nations to grow their export earnings through manufactured goods and services.” Kennedy has recently moved from being an Associate Investigator to his new role as Principal Investigator in
the MacDiarmid Institute. He sees it as “a pathway to enhance the scientific understanding of our new nanomaterials through collaborations with the Institute’s multidisciplinary investigators.” Using the MacDiarmid Institute’s facilities, capabilities and networks, Kennedy hopes to understand his newly created materials better. He also feels that his “small team at GNS Science”
will be complemented by the “larger network” the MacDiarmid Institute offers by, particularly because of its focus on advanced materials and nanotechnology. Kennedy is also a Principal Investigator in the Materials Accelerator, which is working with companies to develop high- value export products that incorporate multiple materials, such as plastics, metals, composites, ceramics, conducting polymers, bio-materials, and coatings. He sees his work benefitting the country as a whole by taking fundamental research into New Zealand’s industries.

John Kennedy Principal Scientist at the National Isotope Centre, GNS Science (Institute of Geological and Nuclear Science).

  • Has a Masters in physics at Loyola College, Chennai and a PhD in physics at Indira Gandhi Centre for Atomic Research (IGCAR), Kalpakkam in 1999.
  • Worked as a post-doctoral fellow in Belgium and France.
  • Moved to New Zealand in 2001.
  • Research background: Dr. Kennedy has pursued wide range of research projects in thin films, nanotechnology, and application of ion beam analysis technique for characterising advanced materials, biology, environmental and agricultural samples.
  • Current research: He is currently investigating metal and metal oxide nanoparticle growth and their structural, electrical, optical and magnetic properties, metallic nanoclusters, graphene and multiferroics nanostructures. His team is working on developing proof-of-concept sensor devices. He has published 150 journal papers and attended more than 35 conferences related to advanced materials.
Transmission electron microscopy of iron silicate-iron core-shell nanostructures in silica having surprising maneto-optic resonance.

Tungsten oxide nano particles synthesised using GNS Science Arc-discharge system.