On the way to physical nanowire implementation and device fabrication, both chemical and thermal stability of the nanowires should be carefully analyzed. Due to their extremely high surface-to-volume-ratio, nanowire properties are expected to be influenced by adsorbates, surface chemical modifications, and morphological changes at elevated temperatures.

Our group demonstrated that metal nanowires are transformed into chains of nanospheres during annealing due to the Rayleigh instability. The driving force of this process is the minimization of surface energy of the initial wire. Both sphere size and spacing between adjacent spheres depend on the initial wire diameter, material, and crystallinity of the wire.

Recently, we reported the geometrical transformation of metallic copper nanowires, confined in graphitic coating, into crystalline nanoparticles of up to tenfold increased diameter. In situ transmission electron microscopy images at 500 ° C, recorded as movies, provided an exceptional real-time visualization of Cu draining out of the carbon coating. The solid content of the carbon tube is effectively evacuated over micrometer distances towards the open end, transforming each nanowire into a single monocrystalline, facetted Cu particle. Kinetic Monte Carlo simulations propose that this dramatic morphological transformation is driven by surface diffusion of Cu atoms along the wire/tube interface, thus minimizing the total free energy of the system. These investigations are relevant for applications of nanotubes including their use as storage media for atoms and small molecules, as nanoscale capsules for chemical reactions, and as nanopipettes for material delivery.

Recent Publications

• Low temperature annealing effects on the stability of Bi nanowires, M. Cassinelli, A. Romanenko, H. Reith, F. Völklein, W. Sigle, C. Trautmann, and M.E. Toimil-Molares, Physica status solidi (a) 213 (2016) 603-609.
• Pipetting Nanowires: In-Situ Visualization of Solid State Nanowire to nanoparticle Transformation Driven by Surface Diffusion Mediated Capillarity, M.E. Toimil-Molares, W. Sigle, L. Roentsch, K.H. Heinig, C. Trautmann, R. Neumann, Advanced Functional Materials 22 (2012) 695.
• Influence of crystallinity on the Rayleigh instability of gold nanowires, S. Karim, M.E. Toimil-Molares, W. Ensinger, A.G. Balogh, T.W. Cornelius, E.U. Khan, R. Neumann, Journal of Physics D- Applied Physics 40 (2007) 3767.
• Morphological evolution of Au nanowires controlled by Rayleigh instability, S. Karim, M.E. Toimil-Molares, A.G. Balogh, W. Ensinger, T.W. Cornelius, E.U. Khan, R. Neumann, Nanotechnology 17 (2006) 5954.
• Fragmentation of nanowires driven by Rayleigh instability, M.E. Toimil-Molares, A.G. Balogh, T.W. Cornelius, R. Neumann, C. Trautmann, Appl. Phys. Lett. 85 (2004) 5337.

GSI contact: m.e.toimilmolares(at)gsi.de

MAT beam time schedule 2024

Beam time at GSI

Gratulation

Wir gratulieren Nils Ulrich herzlich zum erfolgreichen Abschluss seiner Promotion am 18. Oktober 2024 an der TU Darmstadt. In seiner Doktorarbeit beschäftigte sich Nils mit freistehenden, nanostrukturierten Kupferdrahtnetzwerken als Katalysatoren für die elektrochemische CO₂-Reduktion. Nils hat bereits vor fast 2 Jahren eine spannende neue Forschungsaufgabe in der Galvanikindustrie übernommen. Wir wünschen ihm Zufriedenheit und Erfolg.

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Congratulation

We congratulate Nils Ulrich on the successful completion of his PhD thesis on October 18, 2024, at TU Darmstadt. In his thesis project, Nils investigated free-standing, nanostructured copper wire networks as catalysts for electrochemical CO₂ reduction. Nils has already taken on an exciting new research position in the galvanic industry. We wish him continued satisfaction and success.

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Giersch Award für Maxim Saifulin

Dr. Maxim Saifulin wurde mit dem Preis der Giersch-Stiftung für herausragende Dissertationen 2024 ausgezeichnet. Er erhielt den Preis für seine Arbeit „Fast scintillating ZnO ceramics for relativistic heavy-ion beam diagnostics“. Die Arbeit basiert auf einem gemeinsamen Projekt der Abteilungen Strahldiagnostik und Materialforschung und befasste sich mit der Entwicklung eines ultraschnellen Keramikdetektors für ionisierende Strahlung auf der Basis von Zinkoxid-Nanokristallen. Aufgrund seiner hohen Strahlungsresistenz hat dieses Material ein erhebliches Potenzial für Anwendungen in Strahlkontrollsystemen an Schwerionenbeschleunigeranlagen.

Giersch Award for Maxim Saifulin

Dr. Maxim Saifulin was honored with the Giersch Foundation's Award for Outstanding Doctoral Thesis 2024. He received the prize for his work “Fast scintillating ZnO ceramics for relativistic heavy-ion beam diagnostics“. This research was a collaborative project between the Beam Diagnostic and Materials Research departments focusing on the development of an ultrafast ceramic detector for ionization radiation based on zinc oxide nanocrystals. Due to its high radiation resistance, this material holds considerable potential for applications in beam control systems at heavy ion accelerator facilities.