Defects go deep at high temperature

Temperature dependence of helium-implantation-induced lattice swelling in polycrystalline tungsten: X-ray micro-diffraction and Eigenstrain modelling I de Broglie, CE Beck, W Liu, F Hofmann Scripta Materialia 107 (2015) 96-99 Using synchrotron X-ray micro-diffraction and Eigenstrain analysis the distribution of lattice swelling near grain boundaries in helium-implanted polycrystalline tungsten is quantified. Samples heat-treated at up to 1473 KContinue reading “Defects go deep at high temperature”

Helium: the gremlin in tungsten

Lattice swelling and modulus change in a helium-implanted tungsten alloy: X-ray micro-diffraction, surface acoustic wave measurements, and multiscale modelling F Hofmann, D Nguyen-Manh, MR Gilbert, CE Beck, JK Eliason, AA Maznev, W Liu, DEJ Armstrong, KA Nelson, SL Dudarev Acta Materialia 89 (2015) 352-363 Using X-ray micro-diffraction and surface acoustic wave spectroscopy, we measure latticeContinue reading “Helium: the gremlin in tungsten”

Phonon Lifetime in Silicone Membranes

Lifetime of high-order thickness resonances of thin silicon membranes AA Maznev, F Hofmann, J Cuffe, JK Eliason, KA Nelson Ultrasonics DOI: 10.1016/j.ultras.2014.02.016 Femtosecond laser pulses are used to excite and probe high-order longitudinal thickness resonances at a frequency of ∼270 GHz in suspended Si membranes with thickness ranging from 0.4 to 15 μm. The measuredContinue reading “Phonon Lifetime in Silicone Membranes”

Probing a single dislocation

X-ray micro-beam characterization of lattice rotations and distortions due to an individual dislocation F Hofmann, B Abbey, W Liu, R Xu, BF Usher, E Balaur, Y Liu Nature Communications 4:2774 (2013) Understanding and controlling the behaviour of dislocations is crucial for a wide range of applications, from nano-electronics and solar cells to structural engineering alloys.Continue reading “Probing a single dislocation”

Phonon Lifetime in a Superlattice

Intrinsic to extrinsic lifetime transition in a GaAs-AlAs superlattice Felix Hofmann, Jivtesh Garg, Alexei A Maznev, Adam Jandl, Mayank Bulsara, Eugene A Fitzgerald, Gang Chen, Keith A Nelson Journal of Physics: Condensed Matter 2013 25:29540 We have measured the lifetimes of two zone-center longitudinal acoustic phonon modes, at 320 and 640 GHz, in a 14Continue reading “Phonon Lifetime in a Superlattice”