Structure and Magnetism of Materials

Introduction

Our research covers a wide range of materials science, from quite fundamental studies of the unusual properties of two-dimensional magnetic systems to the very applied use of neutron scattering in studying problems encountered in manufacturing metal components. In between, we explore the properties and structures of technologically relevant oxide ceramics, and use diffuse scattering of X-rays, neutrons and electrons to better understand the local (nanoscale if you like) ordering in solids, with a particular emphasis on oxide ceramics and molecular crystals.
     The work on short-range order (SRO) is done in conjunction with the Disordered Materials group in the Research School of Chemistry at ANU.
     The work on oxides ceramics is done in conjunction with the Solid State Inorganic Chemistry group in the RSC, while magnetic studies, whether on oxides or other materials, are done in collaboration with the School of Physical, Environmental and Mathematical Sciences at the ADFA campus of the University of New South Wales.
     Throughout our work, a common thread is diffraction, and particularly X-ray and neutron diffraction. The X-ray work is done primarily at the ANU, with experimental visits to synchrotrons around Australia and the world when necessary. Much of the neutron diffraction is done at the Bragg Institute. The Bragg Institute, based at ANSTO, offers many opportunities to students, including year-long internships and postgraduate co-supervision and collaboration. Other neutron work is done at the ISIS neutron source in the UK, and elsewhere around the world.

Group leader, Darren Goossens, is an Australian Institute of Nuclear Science and Engineering (AINSE) Research Fellow. AINSE provides access to nuclear-related science for Australia-based researchers. They offer post graduate awards as well as providing the link to ANSTO.

Research interests

Disorder in Materials is a very common phenomenon. It occurs in molecular crystals, ceramic oxides, metals -- almost every type of material. In crystalline materials disorder means local departures from the average structure. This could be due to flexing of molecules and frameworks, disordered substitution of atomic species, crystal defects and so on. Indeed, few real systems are really free of disorder. When the disorder is correlated over the short range (nanometres), it results in broad features in the diffraction pattern. Interpreting these allows us to understand the disorder, and gain insight into the physics and chemistry of the material, insights beyond those available when studying only the Bragg peaks in the diffraction pattern, as is most commonly done. Web version of a lecture on diffuse scattering and disorder, presented at ANSTO/AINSE/IAEA Summer School, Dec 2007.

Structure of Oxides: Properties found in oxide materials include superconductivity, ordered magnetism, piezoelectricity and multiferroic behaviour. We use a combination of bulk-property studies (dielectric, magnetic and so on) coupled with detailed structural studies using neutron, X-ray and electron diffraction, to try to make the link between structure and function in such materials. Once this relationship is understood, new materials can be 'designed', with new and improved properties.

Neutron Scattering Study of Metal Injection Moulding is an example of using cutting-edge scientific infrastructure to tackle a problem of industrial significance. Metal injection moulding (MIM) is a process which allows precise parts to be made as near-cast densities, but at lower cost and extremely high precision, allowing very small components to be fabricated. By using in situ neutron diffraction on the WOMBAT diffractometer at ANSTO, we can monitor the evolution of the final part as it happens, allowing us to better optimise the process, controlling things like phase composition of the final product more effectively.

Magnetism in Two Dimensions occurs in a range of materials, and is of fundamental interest. We are interested in the interrelationship of critical behaviour, spin dimensionality and the dimensionality of the magnetic system. The types of magnetic ordering present as a function of applied field, temperature and composition, and the effect of magnetic mixing and dilution on the properties and structures are the main areas of study. Key tools include magnetometry and neutron diffraction, as the neutron scatters from the magnetic moment of an atom.

Group members:

Darren Goossens (AINSE Research Fellow, Group Leader) - goossens__AT__rsc.anu.edu.au
Ross Whitfield (Ph.D. Scholar)
Daniel James (Honours student)

Former group members:

Jessica Hudspeth (Honours student, 2008)

Selected Publications Full List

D.J.Goossens and M.J.Gutmann, 'Revealing how interactions lead to ordering in para-terphenyl', Physical Review Letters, 102 (2009) 015505-1-4.

J.M.Hudspeth, D.J.Goossens, A.J.Studer, R.L.Withers and L.Norén, 'The crystal and magnetic structures of LaCa₂Fe₃O₈ and NdCa₂Fe₃O₈', J. Phys.: Condens. Matt., 21 (2009) 124206.

T.R.Welberry and D.J.Goossens, 'Different models for the polar nanodomain structure of PZN and other relaxor ferroelectrics', Journal of Applied Crystallography 41 (2008) 606-614.

D.J.Goossens, A.P.Heerdegen, T.R.Welberry and A.G.Beasley, 'The Molecular Conformation of Ibuprofen, C₁₃H₁₈O₂, Through X-ray Diffuse Scattering', International Journal of Pharmaceutics 343 (2007) 59-68.

D.J.Goossens, T.R.Welberry, A.P. Heerdegen and M.J. Gutmann, 'Simultaneous Fitting of X-ray and Neutron Diffuse Scattering Data', Acta Crystallographica A A63 (2007) 30-35.

T.R.Welberry, D.J.Goossens and M.J.Gutmann, 'The Chemical Origin of Polar nano-domains in PbZn_1/3Nb_2/3O₃ (PZN)', Phys. Rev. B 74 (2006) 224108.

R.A.Robinson, D.J.Goossens, M.S.Torikachvili, K.Kakuri and H.Okamura, 'A quantum multi-critical point in CeCu_6-xAu_x', Physica B 385-386 (2006) 38-40.

D.J.Goossens, T.R. Welberry, M.E. Hagen and J.A. Fernandez-Baca, 'Structural phase transition in deuterated benzil C₁₄D₁₀O₂: Neutron inelastic scattering', Phys. Rev. B 73 (2006) 134116.

W.D.Hutchison, D.J.Goossens, K.Nishimura, K.Mori, Y.Isikawa and A.J.Studer, 'Magnetic Structure of TbNiAl₄', J. Magn. & Magn. Mat. 301 (2006) 352-358.

M.James, K.S.Wallwork, R.L.Withers, D.J.Goossens, K.F.Wilson, J.Horvat, X.L.Wang and M.Collela, 'Structure and Magnetism in the Oxygen-Deficient Perovskites Ce_1-xSr_xCoO_3-δ (x ≥ 0.90)', Mat. Res. Bull. 40(8) (2005) 1415-1431.

D.J.Goossens, K.F.Wilson, M.James, A.J.Studer and X.L.Wang, 'Structural and Magnetic Properties of Y_0.33Sr_0.67CoO_2.79', Phys. Rev. B 69 (2004) 134411.

D.J.Goossens, A.R.Wildes, C.Ritter and T.J.Hicks, 'Order and the nature of the spin flop phase transition in MnPS₃' Journal of Physics: Condensed Matter, 12 (2000) 1845-1854.

D.J.Goossens, A.J.Studer, S.J.Kennedy and T.J.Hicks, 'The impact of magnetic dilution on magnetic order in MnPS₃', Journal of Physics: Condensed Matter 12 (2000) 4233-4242.