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Scientific Highlights

A. Mailman, S.M. Winter, X. Yu, C.M. Robertson, W. Yong, J.S. Tse, R.A. Secco, Z. Liu, P.A. Dube, J.A. Howard, R.T. Oakley.

In principle the unpaired electrons provided by a solid state array of neutral radicals should be capable of serving as charge carriers, giving rise to a half-filled (f = ½) energy band and a metallic ground state. The problem with the idea lies in the fact that there is an intrinsically high Coulombic barrier (U) to charge transfer in such a system. Overcoming the onsite charge repulsion requires radicals with extensive spin delocalization to lower U, and strong intermolecular resonance interactions to increase the electronic bandwidth W. When W > U, the Mott-Hubbard gap ΔE = U - W should vanish and a metallic state prevail.

V. Fallah, A. Korinek, N. Ofori-Opoku, N. Provatas, S. Esmaeili.

Early-stage solute clustering in solution treated precipitation hardening alloys strongly influences their aged microstructure and thus their mechanical properties. In this study, the clustering phenomenon in a solution treated and naturally aged Al–Cu alloy is characterized using High Resolution Transmission Electron Microscopy (HRTEM) and High Resolution Scanning Transmission Electron Microscopy (HRSTEM). The structural evolution of early clusters revealed by HRTEM-HRSTEM is compared against the Phase Field Crystal (PFC) simulations of dislocation-induced clustering [1,2] in a naturally-aged Al–2.5 at.% Cu alloy.

Graeme Luke, Tom Timusk, J. C. Seamus Davis.

The behaviour of simple metals such as sodium, copper and aluminum is well understood using traditional theories of solid state physics. Magnetic ordering, such as ferromagnetism in iron or more complicated forms such as the spiral state in chromium are also well understood. Superconductivity in conventional metals was understood theoretically by the 1960’s following the work of Bardeen Cooper and Schrieffer. Metals where localized magnetic moments interact with delocalized conduction electrons are less well understood.

B.D. Gaulin, M.C. Rheinstadter, E.D. Cranston, K. Dalnoki-Veress, R.M. Epand, C. Fradin, T.R. Hoare, Y. Mozarivskyj, R. Pelton, H.D.H. Stover.

The BIMR organized and led a Canada Foundation for Innovation (CFI) New Initiative Fund proposal entitled “SANS for Nanostructured Materials” which was approved towards the end of 2012.

This $7.5M project proposes to build Canada’s only small angle neutron scattering (SANS) facility at the McMaster Nuclear Reactor, and to use this unique facility to study a broad range of nanostructure in materials on length scales from ~ 0.2 nm to ~ 20 nm. When complete and operating in ~ 2016, “SANS for Nanostrctured Materials” will provide unique advanced characterization of materials for about 25 research groups per year, both at McMaster University and at other Canadian universities. It will run 40-50 experiments a year, and is expected to make a big impact on the scientific productivity of the BIMR.

G.A. Botton, C. Bock, M. Bugnet, Z. Mi, P. Prabhudev, G. Radtke, D. Rossouw, X. Sun, S.Y. Woo, G.Z. Zhu.

The Canadian Centre for Electron Microscopy, a national facility operated by the BIMR, was established through funding in the 2004 National Competition from the Canada Foundation for Innovation (CFI) and Ontario Government. While electron microscopy has been at the core of the BIMR for decades, the CCEM started operations in 2006 and formally opened 2008, with the commissioning of the two aberration-corrected FEI Titan microscopes. The CCEM facility is been used by over 300 research groups spread across the country accessing the broad suite of instruments from the variable-pressure SEM to the aberration-corrected and monochromated microscopes. Here we demonstrate the application of the CCEM instruments to a range of materials application highlighting a small subset of research carried out at the BIMR, namely related to sub-Angstrom resolution and sub-0.1eV microscopy and spectroscopy.