CLUSTER

Birth of Solids: Atomic-Scale Processes in Crystal Nucleation

CLUSTER is a research project funded by the European Research Commission (ERC) under the European Union's Horizon 2020 program (grant agreement No. 681312) running from 01/06/2016 through 31/05/2021.

A list of publications from the CLUSTER project can be found here.

Atoms-Clusters.png

The goal of CLUSTER is to explore the fundamental processes which trigger the nucleation and growth of solids. Condensed matter is formed by clustering of atoms, ions or molecules. This initial step is key for the onset of crystallization, condensation and precipitate formation. Yet, despite of the scientific and technological significance of these phenomena, on an atomistic level we merely have expectations on how atoms should behave rather than experimental evidence about how the growth of solid matter is initiated. The classical nucleation theory is commonly in agreement with experiments, provided the original and the final stages are inspected qualitatively. However, the classical theory does not define what fundamentally constitutes a pre-nucleation state or how a nucleus is formed at all. CLUSTER aims at investigating the very early stages of crystalline matter formation on an unprecedented length scale. It shall explore the atomic mechanisms which prompt the formation of solids. Complemented by density functional theory calculations and molecular dynamics simulations, in-situ high-resolution electron microscopy shall be used to investigate the formation, dynamics, stability and evolution of tiniest atomic clusters which represent the embryos of solid matter. Firstly, we investigate the 3D structure of clusters deposited on suspended graphene. Secondly, we focus on cluster formation, the evolution of sub-critical nuclei and the onset of particle growth by thermal activation. Thirdly, using a novel liquid-cell approach in the transmission electron microscope, we control and monitor in-situ cluster formation and precipitation in supersaturated solutions. The results of CLUSTER, which will advance the understanding of the birth of solid matter, are important for the controlled synthesis
of (nano-)materials, for cluster science and catalysis and for the development of novel materials.

Atomic Clusters, Nuclei & Nanoparticles
Pt+cluster.gif

In our experiments with sub-nm sized clusters on amorphous carbon support films, we investigate, e.g., the behaviour of Pt atoms under electron irradiation at different temperatures. We observe a strong dependence of the structures of the clusters as a function of temperature, and find tiniest clusters with the bulk face-centered cubic (fcc) structure. We employ an unconventional fast scanning transmission mode which simultaneously images the structure and probes its stability by electron impact.   

The animation of experimental STEM micrographs shows three Pt clusters. Inset is a model of the 13-atom cluster at the bottom. The 13-atom cluster shows the structure of one single fcc unit cell, missing one corner atom. During the recording, the cluster rotates twice, before two corner atoms detach and the cluster starts deforming, then it gets absorbed by the larger cluster.  (Denoised, animated in real time)

 

Particle Nucleation and Growth in Ionic Liquids
Au_IonicLiquid_256.gif
Gold particle growth by coalescence and by single-atom attachments with subsequent particle relaxation in ionic liquid at elevated temperature in dark-field STEM.

Ionic liquids have low vapor pressures and can be inserted into the high vacuum column of the microscope as free-standing, thin, liquid layers. In terms of their chemical properties, they are more complex than the solvents typically used in liquid-cell experiments. However, ionic liquids allow for high resolution observations in very thin liquid films, similar to gas phase experiments, but still in a liquid environment. Therefore, ionic liquids render insights complementary to results from liquid-cell and gas phase experiments and provide an additional, useful tool for studying particle nucleation and growth processes in situ at variable temperatures without being limited in resolution by electron transparent windows used in conventional liquid cells in STEM/TEM.

See, e.g., Keller et al., Micron 117 (2019) 16-21.

Liquid cell (S)TEM
Au+HiInt.gif

Gold nanoparticles particles nucleate and growth in a aqueous solution of HAuCl4 under electron irradiation.

(Data recorded on Empa's FEI Titan Themis operated at 300 kV, Protochips Poseidon liquid-cell holder, HAADF-STEM)

Au+LInt.gif

Reducing the electron dose, the growth mode changes: the particles don't show facetted growth, but a dentritic growth mode.

(Movies: 10-times faster than experiment)

 

Publications: CLUSTER Project

Peer-Reviewed Journal Articles

A complete list of current publications of Empa's Electron Microscopy Group can be found here.

  1. W. Dachraoui, M. I. Bodnarchuk, R. Erni, Direct imaging of the atomic mechanisms governing the growth and shape of bimetallic Pt-Pd nanocrystals by in situ liquid cell STEM, ACS Nano 16 (2022) 14198-14209.

  2. W. Dachraoui, T. R. Henninen, D. Keller, R. Erni, Multi-step atomic mechanism of platinum nanocrystals nucleation and growth revealed by in-situ liquid cell STEM, Scientific Reports 11 (2021) 23965.

  3. W. Dachraoui, M. I. Bodnarchuk, A. Vogel, M. V. Kovalenko, R. Erni, Unravelling the shell grwoth pathways of Pd-Pt core-shell nanocubes at atomic level by in situ liquid cell electron microscopy, Applied Physics Reviews 8 (2021) 041407.

  4. W. Dachraoui, D. Keller, T. R. Henninen, O. Ashton, R. Erni, Atomic mechanisms of nanocrystallization via cluster-clouds in solution studied by liquid-phase scanning transmission electron microscopy, Nano Letters 21 (2021) 2861-2869.

  5. T. R. Henninen, D. Keller, R. Erni, Structure Matters - Direct In‐situ Observation of Cluster Nucleation at Atomic Scale in a Liquid Phase, ChemNanoMat 7 (2021) 110-116.

  6. D. Keller, T. R. Henninen, R. Erni, Atomic mechanisms of gold nanoparticle growth in ionic liquids studied by in situ scanning transmission electron microscopy, Nanoscale 12 (2020) 22511-22517.

  7. F. Wang, T. R. Henninen, D. Keller, R. Erni, Noise2Atom: unsupervised denoising for scanning transmission electron microscopy images, Applied Microscopy 50 (2020) 23 (1-9).

  8. M. Campanini, L. Nasi, F. Albertini, R. Erni, Disentangling nanoscale electric and magnetic fields by time-reversal operation in differential phase-contrast STEM, Applied Physics Letters 117 (2020) 154102.

  9. Y. Zhao, W. Wan, Y. Chen, R. Erni, C. A. Triana, J. Li, C. K. Mavrokefalos, Y. Zhou, G. R. Patzke, Understanding and optimizing ultra-thin coordination polymer derivatives with high oxygen evolution performance, Advanced Energy Materials 10 (2020) 2002228.

  10. Y. Jiang, T. Feurer, R. Carron, G. Torres Sevilla, T. Moser, S. Pisoni, R. Erni, M. D. Rossell, M. Ochoa, R. Hertwig, A. N. Tiwari, F. Fu, High-mobility In2O3:H electrodes for four-terminal perovskite/CuInSe2 tandem solar cells, ACS Nano 14 (2020) 7502-7512.

  11. M. Campanini, K. Eimre, M. Bon, C. A. Pignedoli, M. D. Rossell, R. Ern, Atomic-resolution differential phase contrast STEM on ferroelectric materials: a mean-field approach, Physical Review B 101 (2020) 184116.

  12. F. Wang, A. Eljarrat, J. Müller, T. R. Henninen, R. Erni, C. T. Koch, Multi-resolution convolutional neural networks for inverse problems, Scientific Reports 10 (2020) 5730.

  13. S. Griffiths, J. R. Croteau, M. D. Rossell, R. Erni, A. De Luca, N. Q. Vo, D. C. Dunan, C. Leinenbach, Coarsening- and creep resistance of precipitation-strengthened Al-Mg-Zr alloys processed by selective laser melting, Acta Materialia 188 (2020) 192-202.

  14. Y. Zhao, C. K. Mavrokefalos, P. Zhang, R. Erni, G. R. Patzke, Self-templating strategies for transition metal sulfide nanoboxes as robust bifunctional electrocatalysts, Chemistry of Materials 32 (2020) 1371-1383. 

  15. T. R. Henninen, M. Bon, F. Wang, D. Passerone, R. Erni, The structure of sub-nm Platinum clusters at elevated temperatures, Angewandte Chemie Internation Edition 59 (2020) 839-845.

  16. N. Ahmad, M. Bon, D. Passerone, R. Erni, Template assisted in situ synthesis of Ag@Au bimetallic nanostructures employing liquid-phase transmission electron microscopy, ACS Nano 19 (2019) 13333-13342.

  17. J. Nordlander, M. Campanini, M. D. Rossell, R. Erni, Q. N. Meier, A. Cano, N. A. Spaldin, M. Fiebig, M. Trassin, The utrathin limit of improper ferroelectricity, Nature Communications 10 (2019) 5591(1-7).

  18. J. Li, W. Wan, C. A. Triana, Z. Novotny, J. Osterwalder, R. Erni, G. R. Patzke, Dynamic role of cluster cocatalysts on molecular photoanodes for water oxidation, Journal of the American Chemical Society (JACS) 141 (2019) 12839-12848.

  19. M. Bon, N. Ahmad, R. Erni, D. Passerone, Reliability of two embedded atom models for the description of Ag@Au nanoalloys, The Journal of Chemical Physics 151 (2019) 064105.

  20. D. Keller, T. R. Henninen, R. Erni, Formation of gold nanoparticles in a free-standing ionic liquid triggered by heat and electron irradiation, Micron 117 (2019) 16-21.

  21. N. Ahmad, D. Keller, M. D. Rossell, R. Erni, In situ template assisted growth of Ag@Au bimetallic nanostructures, Microscopy and Microanalysis 25 (Suppl. 1) (2019) 41-42.

  22. N. Ahmad, D. Keller, M. D. Rossell, R. Erni, Liquid Phase Studies of Nanomaterials, Chimia 72 (2018) 727.
  23. Y. Zhang, D. Keller, M. D. Rossell, R. Erni, Formation of Au nanoparticles in liquid cell transmission electron microscopy: from a systematic study to engineered nanostructures, Chemistry of Materials 29 (2017) 10518-10525. Download pdf.
  24. C. P. Guntlin, S. T. Ochsenbein, M. Wörle, R. Erni, K. V. Kravchyk, M. V. Kovalenko, Popcorn-shaped FexO (Wüstite) nanoparticles from a single-source precursor: colloidal synthesis and magnetic properties, Chemistry of Materials 30 (2018) 1249-1256. Download pdf.
  25. Y. Zhang, C. Guerra-Nunez, I. Utke, J. Michler, P. Agrawal, M. D. Rossell, R. Erni, Atomic layer deposition of titanium oxide on single layer graphene: an atomic scale study towards understanding nucleation and growth, Chemistry of Materials 29 (2017) 2232-2238. Download pdf.
  26. H. K. Hong, J. Jo, D. Hwang, J. Lee, N. Y. Kim, S. Son, J. H. Kim, M. J. Jin, Y. C. Jun, R. Erni, S. K. Kwak, J. W. Yoo, Z. Lee, Atomic scale study on growth and heteroepitaxy of ZnO monolayer on graphene, Nano Letters 17 (2017) 120-127.  Download pdf.
Other Articles
  1. F. Wang, J. Müller, A. Eljarrat, T. R. Henninen, R. Erni, C. T. Koch, Solving inverse problems with multi-scale deep convolutional neural networks, arXiv:1810.12183v1 (2018).
Conference Presentations
  1. R. Erni, W. Dachraoui, D. Keller, T. R. Henninen, F. Wang, Liquid-phase atomic-scale investigations of crystal nucleation, particle growth and core-shell formation using in-situ scanning transmission electron microscopy, ELMINA 2022, Belgrade (RS), August 23, 2022. (invited)
  2. R. Erni, D. Keller, W. Dachraoui, Electron-induced particle nucleation-and-growth reactions studied by atomic-resolution liquid-phase scanning transmission electron microscopy, CECAM Workshop on Multiscale modelling of irradiation-driven processes, Lausanne (CH), March 16-18, 2022. (invited)
  3. R. Erni, D. Keller, T. R. Henninen, M. Bon, F. Wang, W. Dachraoui, Atomic mechanisms in crystal nucleation and particle growth by liquid-phase STEM, 17th International Conference on Electron Microscopy, Krakow (PL), November 30 – December 2, 2020. (invited, online)
  4. T. R. Henninen, D. Keller, R. Erni, From atoms to particles: Hetero- and homogeneous nucleation of Pt at atomic scale in ionic liquid, Gordon Research Conference, Liquid Phase Electron Microscopy, Lucca (IT), January 26-31, 2020.
  5. D. Keller, T. R. Henninen, R. Erni, In situ observation of gold nanoparticle growth in thin ionic liquid layers, Microscopy Conference 2019, Berlin (DE), September 2-5, 2019. (oral presentation)
  6. F. Wang, T. R. Henninen, R. Erni, Blind denoising STEM images with deep convolutional neural network, Microscopy Conference 2019, Berlin (DE), September 2-5, 2019. (poster)
  7. T. R. Henninen, F. Wang, D. Keller, R. Erni, Stability and dynamics of sub-nm Pt clusters on a carbon surface and in ionic liquid, Microscopy Conference 2019, Berlin (DE), September 2-5, 2019. (poster)
  8. R. Erni, D. Keller, T. R. Henninen, M. Bon, F. Wang, Structure, dynamics and stability of small Pt clusters at elevated temperature, EUROMAT, Stockholm (SE), September 2-5, 2019. (invited presentation)
  9. R. Erni, M. Campanini, M. D. Rossell, Ordering and defects in complex functional oxides studied by analytical STEM, Joint ISAF-ICE-EMF-IWPM-PFM Meeting, Lausanne (CH), July 15-19, 2019. (invited presentation)
  10. M. Bon, N. Ahmad, D. Passerone, R. Erni, Reliability of the two embedded atom models for the description of Au-Ag nanoalloy growth, Challenges in modeling and simulations of nanoparticles in complex environments, Genova (IT), May 27-29, 2019. (poster, poster prize)
  11. N. Ahmad, Nanoscale liquid phase in situ observations of structural transformations of Au and Au-Cu nanostructures, CISCEM 2018, Saarbrücken (DE), October 10-12, 2018. (oral)
  12. N. Ahmad, In situ Template Assisted Growth of Ag@Au Bimetallic Nanostructuress, 19th International Microscopy Congress IMC 2018, Sydney (AU), September 9-14, 2018. (oral)
  13. R. Erni, Unconventional Imaging by Scanning Transmission Electron Microscopy, 20th YUCOMAT, Herceg Novi (CS), September 3-7, 2018. (invited presentation)
  14. T. Henninen, M. Bon, D. Passerone, R. Erni, Temperature Dependent Quasimolten Crystallinity of Sub-nm Pt and Au Clusters Observed in 3D by Fast Dynamic STEM, ELMINA, 1st International Conference on Electron Microscopy of Nanostructures, Belgrade (CS), August 27-29, 2018. (poster, poster prize)
  15. R. Erni, Possibilities of differential phase contrast STEM to study functional oxides, ELMINA, 1st International Conference on Electron Microscopy of Nanostructures, Belgrade (CS), August 27-29, 2018. (invited presentation)
  16. D. Keller, T. Henninen, R. Erni, In Situ Gold Nanoparticle Formation in a Free-Standing Ionic Liquid Layer Triggered by Heat and Electron Irradiation, SCANDEM, Copenhagen (DK), June 26-28, 2018. (oral presentation)
  17. T. Henninen, M. Bon, D. Passerone, R. Erni, Temperature Dependent Quasimolten Crystallinity of sub-nm Pt and Au Clusters Observed in 3D by Fast Dynamic STEM, SCANDEM, Copenhagen (DK), June 26-28, 2018. (poster)
  18. T. Henninen, M. Bon, D. Passerone, R. Erni, Temperature Dependent Quasimolten Crystallinity of sub-nm Pt and Au Clusters Observed in 3D by Dynamic Scanning Transmission Electron Microscopy, Nanoconvention, ETH Zurich (CH), June 6&7, 2018. (poster)
  19. R. Erni, D. Keller, M. Rossell, Y. Zhang, N. Ahmad, T. Henninen, M. Campanini, Advanced Analytics by Scanning Transmission Electron Microscopy, Nanoconvention, ETH Zurich (CH), June 7, 2018. (oral, invited)
  20. D. Keller, Y. Zhang, M. D. Rossell, R. Erni. Gold Nanoparticle Growth in Liquid Cell Transmission Electron Microscopy: From a Systematic Study to Engineered Nanostructures.  Microscopy Characterisation of organic-inorganic Interfaces, London, Queen Mary University (UK). February 22-23, 2018. (poster: poster price)
  21. M. Bon, T. Henninen, D. Passerone, R. Erni. Dynamics of sub-nm Pt clusters on carbon-based materials: Computation meets STEM measurements.  DPG Conference 2018, Berlin. March 11-16, 2018. (oral)
  22. R. Erni, Y. Zhang, T. Henninen, D. Keller, Towards atomic-scale studies of nucleation and growth of matter by in situ (scanning) transmission electron microscopy. 13th Multinational Congress on Microscopy, MCM2017, Rovinj (HR), September 24-29, 2017. (oral, invited)
  23. T. Henninen, M. D. Rossell, R. Erni, Temperature dependent dynamics and structure of atomic clusters in 3D by high speed STEM. 13th Multinational Congress on Microscopy, MCM2017, Rovinj (HR), September 24-29, 2017. (oral)
  24. Y. Zhang, C. Guerra-Nuñez, I. Utke, J. Michler, P. Agrawal, M. D. Rossell, R. Erni, Understanding and controlling atomic layer deposited TiO2 on carbon-based nanomaterials – growth, structure and interface. Microscopy Conference 2017, MC2017, Lausanne (CH), August 21-25, 2017. (oral)
  25. T. Henninen, M. D. Rossell, R. Erni, Studying the dynamics of atomic clustering in 3D by HAADF-STEM. Microscopy Conference 2017, MC2017, Lausanne (CH), August 25-29, 2017. (oral)
  26. D. Keller, Y. Zhang, R. Erni, Observation of nucleation and growth processes of Au nanoparticles
    at high dose rates. Microscopy Conference 2017, MC2017, Lausanne (CH), August 25-29, 2017. (poster)
Seminars & Workshop Presentations

 

  1. R. Erni, W. Dachraoui, D. Keller, T. R. Henninen, F. Wang, Atomic scale mechanisms of particle nucleation in liquid-phase STEM, StEM Workshop, Ringberg Castle, Lake Tegernsee, (D), July 20-22, 2022. (invited)
  2. M. Campanini et al., Exploring Phase Transitions by in-situ Scanning Transmission Electron Microscopy, SSOM Seminar, ETH Zurich (CH), October 30, 2019.
  3. N. Ahmad,  In situ Template Assisted Growth of Ag@Au Bimetallic Nanostructuress, In-situ Workshop Protochips-Empa, Dübendorf (CH), October 16-17, 2018.
  4. T. R. Henninen,  Crystallinity and Dynamics of sub-nm Pt Clusters at Elevated Temperatures, In-situ Workshop Protochips-Empa, Dübendorf (CH), October 16-17, 2018.
  5. R. Erni, D. Keller, Y. Zhang, M. D. Rossell, N. Ahmad, T. Henninen, M. Campanini, Advanced Analytics by Scanning Transmission Electron Microscopy, Dectris Ltd., Baden (CH), June 28, 2018.
  6. R. Erni, Y. Zhang, T. Henninen, D. Keller, M. D. Rossell, M. Campanini, M. Bon, D. Passerone, Towards an atomic-scale understanding of nucleation and growth of matter by in-situ (S)TEM, University of Vienna, January 19, 2018.
  7. R. Erni, Y. Zhang, T. Henninen, D. Keller, Towards an atomic-scale understanding of nucleation and growth of matter by in-situ (S)TEM. NORTEM & University of Oslo, Seminar, Oslo (NO), December 13, 2017.
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