Solid state reactions, interfaces, and stress in core-shell nanostructures
Final Report Abstract
The project studied solid state reactions in core-shell nanostructures with atom probe techniques and complementary TEM and XPS. Hemispherical geometries, produced by sputter deposition of thin films on the apex of tungsten wires are the dominant model geometry, but also core-shell nanowires are considered. Investigations were concentrated on metallic triple layers Al/Cu/Al and, more extensively, on various silicide forming systems e.g. Cu/a-Si/Cu, Ni/a-Si/Ni, Cr/a-Si/Cr. Interestingly, all triple layer systems have shown a significant asymmetry in the growth rate of the reaction product at the interfaces. In the case of Al/Cu/Al, the intermetallic product Al2Cu growth was faster at the inner interface at which Cu is stacked on top of Al, while all silicide systems showed far faster growth when the metal is stacked on top of a-Si. While the origin of the first appears to be elastic stress coupled with plastic relaxation and vacancy supersaturation, the latter effect in the silicide could be shown by APT to be caused by tiny differences in the initial chemical sharpness of the Me/Si interfaces after layer deposition. While a very sharp interface requires a rather long incubation period for the nucleation of the silicide, a chemically broader interface leads to almost spontaneous instantaneous formation of the silicide. This behavior could be shown to be in perfect quantitative agreement with a polymorphic nucleation mechanism, starting from the intermixed, but disordered interface. For cylindrical core-shell nanowires, a theoretical continuum set of equations was derived to simulate the growth of the intermetallic product. The mode predicts that the growth rate of the products might be sensitively controlled by axial compressive or tensile stress. The described growth asymmetry can be controlled and increasingly suppressed with increasing tensile stress. Core/shell stainless steel/CrC nanowires were experimentally demonstrated by electroplating into trackedged membranes. By thermal reaction, the CrC shell is formed. With further annealing these wires form hollow nanotubes of CrC.
Publications
- ‘Growth kinetics and interface structure of copper Silizides studied by atom probe tomography’, Phys. Stat. Sol. (c), (2013) 1724-1727
M. Ibrahim, B. Parditka, A.Fuhrich, Z.Balogh, P.Stender, Z. Erdélyi, and G. Schmitz
(See online at https://doi.org/10.1002/pssc.201300370) - ‘Phase growth in amorphous Si-Cu system: combination of SNMS, XPS, XRD, and APT techniques’, Acta Materialia 61 (2013) 7173-7179
Bence Parditka, Mariana Verezhak, Zoltán Balogh, Attila Csik,Gábor A. Langer, Dezső L. Beke, Mohammed Ibrahim, Guido Schmitz, Zoltán Erdélyi
(See online at https://doi.org/10.1016/j.actamat.2013.08.021) - ‘On the influence of the stacking sequence in the nucleation of Cu3Si in sputter deposited Cu-amorphous Si thin films’, Acta Materialia, 76 (2014) 306-313
M. Ibrahim, Z. Balogh, P. Stender, R. Schlesiger, G.-H. Greiwe, G. Schmitz, B. Parditka, G.A. Langer, A. Csik and Z. Erdélyi
(See online at https://doi.org/10.1016/j.actamat.2014.05.006) - MicroTap: Conjunction of FIB and APT. International Conference APT&M, Gyeongju, Korea Korea 2016 [Posterpreis]
Patrick Stender, Manuel Roussel, Guido Schmitz
- Nucleation controlled reaction of Cu3Si in the field of sharp concentration gradient, Acta Mater. 112 (2016) Pages 315-325
M. Ibrahim, Z. Balogh, P. Stender, D. Baither, G. Schmitz
(See online at https://doi.org/10.1016/j.actamat.2016.04.041) - Phase Transformation in Alloyed Nanowires. DPG Frühjahrskonferenz, Arbeitsgemeinschaft Metall- und Materialphysik 2016 [Posterpreis]
Manuel Roussel, Martin Schellenberger, Tim Lehmann, and Guido Schmitz
- “Reactive diffusion and stresses in nanowires or nanorods”, Acta Materialia 131 (2017) 315-322
Manuel Roussel, Guido Schmitz, Zoltán Erdélyi
(See online at https://doi.org/10.1016/j.actamat.2017.04.001) - ‘Synthesis and thermal reaction of stainless steel nanowires’, Nanoscale 2020, 12, 731
G. Csiszár, M. Schellenberger, G. Schmitz
(See online at https://doi.org/10.1039/C9NR06946A)
