研究热点

An Office of Science user facility jointly operated by Los Alamos and Sandia National Laboratories.

The Center for Integrated Nanotechnologies (CINT) offers world-leading scientific expertise and specialized capabilities to create, characterize, and integrate nanostructured materials at a range of length scales, from nano- to meso-scale. CINT helps scientists perform cutting-edge research in the areas of nanoscience and nanotechnology, providing FREE ACCESS for nonproprietary research. CINT facilities are open to the international research community, including government, academic, and industry researchers.

One of CINT’s core research areas is in-situ S/TEM experiments. Early capabilities focused on electrical and electrochemical property measurements of materials during high-resolution imaging. More recently, the staff has expanded the available techniques to include gaseous environments (ETEM), liquid-cell, mechanics, ion irradiation, laser ablation, cryogenic, heating, and air-free transfer. In-situ investigations have focused on coupled structure-property measurements on real materials, with the CINT user community expanding many of the in-situ method developments. 

CINT Capability Highlights

Energy Storage: Solid-liquid interfacial reactions control the performance of many of today’s portable energy storage technologies. Understanding the mechanisms of ion transfer across these interfaces provides critical insight for engineering solutions to improve performance, such as artificial solid-electrolyte interphases. CINT can analyze these materials and systems using a variety of techniques.    

• Open-Cell In-Situ Electrochemistry: Individual nanowires or nanoparticles may be observed during reaction with charge-transfer ions (lithium, sodium, potassium, etc.)

• Closed-Cell In-Situ Electrochemistry: CINT’s Electrochemical Discovery Platform is a custom-designed microelectromechanical system platform

• Cryogenic FIB Lift-Out and Cryo-S/TEM: Intact investigations of electrode/electrolyte interfaces may be achieved by preparing an electrode-surface cross-section under inert transfer and cryogenic conditions in a focused ion beam (FIB)

• Cryo-TEM: Investigations of electrolytes may be studied using plunge-freezing methods to rapidly cool a thin electrolyte layer, then image any structural features using TEM
• Vacuum-Transfer S/TEM Holder: Allows for loading of a TEM grid in an Ar-filled glovebox for direct transfer into the S/TEM or ETEM

Soft Matter and Beam Sensitive Materials: CINT recently established a cryo-TEM suite dedicated to minimizing the electron dose for imaging materials and interfaces in their native hydrated (or solvated state). This provides an optimized characterization of sensitive materials across multiple length scales. Instruments included are a Talos dedicated cryo-TEM, a Scios 2 Dual-Beam SEM/FIB equipped with a Leica cryogenically-cooled stage, and a Vitrobot for reproducible and controlled vitrification of hydrated samples. Uniquely, CINT also provides Leica cryogenic-transfer equipment including a sample-prep station (VCM), high-vacuum transfer shuttle (VCT500), and a cryogenically-cooled sputter coater (ACE600). This robust and complete workflow allows for the preparation of frozen, electron-transparent lamellae that can be transferred to the TEM without ever leaving a cryogenic environment.

• Talos L120C: Dedicated low dose, low kV TEM (user switchable from 20-120 kV) for imaging beam sensitive materials, and analyzing buried sample features and interfaces

• Scios 2 Dual Beam Cryo-SEM/FIB: Contains a cryo-cooled SEM stage for surface analysis, analysis of buried interfaces, and serial sectioned 3D tomography of soft matter and nanomaterials in their native, hydrated state

• Leica Transfer Equipment: Leica EM VCM enables users to easily put their cryogenic samples on holders under liquid nitrogen

Corrosion: Reactions at the surfaces of metals in contact with various solutions can cause massive structural deterioration, in the form of uniform, localized, and pitting corrosion. In-situ S/TEM has recently been proven as a method to investigate the initiation and propagation mechanisms of localized corrosion, with implications for progression mechanisms that cause pit formation.

• S/TEM Experimental Methodology for Pre-, In-situ, and Post-Characterization: Using ACOM, energy-filtered TEM, EDS mapping, nanobeam diffraction, and high-resolution imaging, the metal sample may be mapped structurally and for the identification of compositional variations

• Cryo-FIB/SEM/EDS/EBSD: Bulk corrosion samples with the corrosive medium intact can be studied using the Scios SEM with an attached Leica cryo-stage

Gas-solid Reactions: CINT offers a 300kV Titan G2 Environmental TEM which is monochromated, image-corrected, and equipped with a Gatan K2-IS camera. The gas cart provides high-level control over the inlet gas composition while minimizing contamination throughout the system. Many different studies may be conducted with an array of TEM holders. We also offer Protochips’ AXON software for minimizing image drift during in-situ reactions.

• Catalysis: Gasses fed directly to the objective lens in the TEM include oxygen, hydrogen, nitrous oxide, methane, carbon monoxide, carbon dioxide, nitrogen, argon, and helium

• Environmental Surface Reactions: Oxidation, reduction, annealing, and electrical break down mechanisms may be investigated
• Hydrogenation: Coupled mechanical studies may be performed using a Hysitron PI-95 TEM holder
• Vapor-Phase Corrosion: A new system has been installed to allow vapor introduction into the ETEM, including water for deliquescence corrosion studies

Publication Highlights

1. Hattar, K.; Bufford, D. C.; Buller, D. L., Concurrent in situ ion irradiation transmission electron microscope. Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms 338 (2014): 56-65.
2. Grosso, R.; Muccillo, E. N. S.; Muche, D. N. F.; Jawaharram, G. S.; Barr, C. M.; Monterrosa, A. M.; Castro, R. H. R.; Hattar, K.; Dillon, S. J., In situ transmission electron microscopy for ultrahigh temperature mechanical testing of ZrO2. Nano Letters (2020).
3. Bufford, D. C., Stauffer, D.; Mook, W. M.; Syed Asif, S. A.; Boyce, B. L.; Hattar, K., High cycle fatigue in the transmission electron microscope. Nano Letters 16, no. 8 (2016): 4946-4953.
4. Watt, J.;  Huber, D. L.; Stewart, P. L., Soft matter and nanomaterials characterization by cryogenic transmission electron microscopy. MRS Bull. 2019, 44 (12), 942-948.
5. Poerwoprajitno, A. R.;  Gloag, L.;  Benedetti, T. M.;  Cheong, S.;  Watt, J.;  Huber, D. L.;  Gooding, J. J.; Tilley, R. D., Formation of branched ruthenium nanoparticles for improved electrocatalysis of oxygen evolution reaction. Small 2019, 15 (17), e1804577.
6. Watt, J.;  Austin, M. J.;  Simocko, C. K.;  Pete, D. V.;  Chavez, J.;  Ammerman, L. M.; Huber, D. L., Formation of metal nanoparticles directly from bulk sources using ultrasound and application to e‐waste upcycling. Small 2018, 14 (17), 1703615.
7. Hayden, S. C.; Chisholm, C.; Grudt, R. O.; Aguiar, J. A.; Mook, W. M.; Kotula, P. G.; Pilyugina, T. S.; Bufford, D.C.; Hattar, K.; Kucharski, T. J.; Taie, I. M.; Orstraat, M. L.; Jungjohann, K. L., Localized corrosion of low-carbon steel at the nanoscale, npj Materials Degradation 3(1), 1 (2019).
8. Harrison, K.; Zavadil, K. R.; Hahn, N. T.; Meng, X.; Elam, J. W.; Leenheer, A.; Zhang, J. -G.; Jungjohann, K. L., Lithium self-discharge and its prevention: Direct visualization through in-situ electrochemical scanning transmission electron microscopy, ACS Nano 11, 11194 (2017).
9. Xie, H.; Tan, X.; Luber, E. J.; Olsen, B.; Kalisvaart, W. P.; Jungjohann, K. L.; Mitlin, D.; Buriak, J. M., β-SnSb for Sodium ion battery anodes: Phase transformations responsible for enhanced cycling stability revealed by in-situ TEM. ACS Energy Letters 3(7), 1670 (2018).

Department of Materials Science and Engineering.
School for the Engineering of Matter, Transport, and Energy. Arizona State University (ASU)

Dr. Peter Crozier has been an active member of the electron microscopy community for over 30 years, making significant contributions to the fields of in-situ microscopy, in-operando microscopy, and vibrational electron energy loss spectroscopy (EELS). The Crozier group conducts research largely in the field of catalysis, across a wide range of materials systems, structures, and length scales. They are key users and supporters of the John M. Cowley Center for High-Resolution Electron Microscopy—one of the world's leading electron microscopy facilities. Moreover, the entire group actively participates in outreach and mentorship of the microscopy community by organizing and leading events at ASU and national conferences.

Recent Work

Recent work from the group focuses on understanding the effects that atomic-scale composition and structure of different materials have on their catalytic activity. For example, the group used vibrational EELS to examine graphitic carbon nitride photocatalysts and in-situ environmental TEM (ETEM) to examine the interfacial behavior between catalysts and their support.

Dr. Crozier presented part of his group’s in-situ ETEM work in the Gatan webinar “In-Situ Electron Energy Loss Spectroscopy for Nanoscale Characterization of Materials Dynamics.” He showed how in-situ ETEM was used to observe the localized structural evolution of a Ni/CeO₂ system under different gas flow conditions. Specifically, varying gas composition while heating the Ni/CeO₂ to 550°C resulted in different carbon growth behavior at the nanocatalyst interfaces. Ethylene (C₂H₄) gas flow resulted in graphite formation on the Ni nanoparticle surface, whereas ethane (C₂H₆) gas flow instead resulted in the amorphization of CeO₂ due to oxygen-induced reaction with C₂H₆. These results highlight key catalytic behavior of the Ni/CeO₂ system when used for hydrocarbon reforming.

Find more information about the Crozier group and their research on their group website. https://crozier.engineering.asu.edu/ 

Watch Dr. Crozier’s webinar on In-Situ EELS 

Publications

https://pubs.acs.org/doi/abs/10.1021/acsanm.8b00102

Material science is at the core of a large majority of research topics at the Centre for Nanoscience and Nanotechnology (C2N). Innovating in this field is of crucial importance. The Materials Department has two general objectives:

• To conduct its own research activities in material science, from the physics of growth to the control of various material properties
• To interact with the 3 other departments (Photonics, Nanoelectronics, Microsystems and Nanobiofluidics), collaborate with external groups and provide samples and devices

Understanding growth mechanisms and correlating the material properties with their growth conditions is one of the main challenges of the Department. To this aim, we use advanced equipment for growth and analysis. We also develop adapted theoretical and numerical tools. Our activities in material science focus mainly on nanostructures made of III-V semiconductors, Si/Ge, novel 2D materials (2D Materials team) and functional oxides (OXIDE team). Hybridization of these various materials is another challenge, opening the way to novel functionalities. These activities are pursued in strong interaction with photonics, nanoelectronics, devices, and systems.

Lab Highlight

In-situ growth in a transmission electron microscope of semiconductor nanostructures: Atomic Step Flow on a Nanofacet

The project Nanomax associates specialists (from the Ecole Polytechnique and C2N) in the epitaxial growth of nano-objects from the experimental and theoretical points of view. 

The goal is to investigate fundamental issues of solid phase nucleation and growth (from a supersaturated vapor phase) that cannot be solved by ex situ observation (due to the evolution of nanostructures during post-growth cooling). The pilot project in NANOMAX is MBE of III-V semiconductor nanowires. Other investigations include chemical vapor deposition of various nano-objects ranging from semiconductor quantum dots to carbon nanotubes. NANOMAX is the first ever attempt to implement MBE in a TEM column. Moreover, its goal is real atomic resolution during growth, which has never been achieved so far. NANOMAX thus implies significant technical developments, regarding both hardware and software, such as the implementation of effusion cells in the vicinity of a modified objective lens and stage (http://www.tempos.fr).

A remarkable specificity of nanocrystals is the strong influence of their surfaces and edges on their properties. The important role of crystal boundaries also manifests itself at the growth stage. Indeed, surfaces influence the morphology and crystalline arrangement of nanostructures, not only as regards thermodynamics but also via their growth dynamics. This is notably illustrated in the vapor-liquid-solid (VLS) growth of semiconductor nanowires (NWs). In this method, vapor containing the NW constituents is supplied to a liquid catalyst nanoparticle. Upon supersaturation of the catalyst droplet, crystallization occurs: A nanocrystal forms, one of its facets in contact with the droplet. This nanofacet is where crystal growth further proceeds. A detailed and real-time observation of the liquid-solid interface is thus expected to clarify the role of the boundaries in the crystallization process. We observe the VLS growth of GaAs NWs in real time. We use a modified FEI environmental TEM equipped with an image aberration corrector. Two ports were designed to implement Ga and As4 molecular beam sources in the TEM. NW formation is catalyzed by Au particles dispersed on a heating carrier membrane, and in situ growth is performed by molecular beam epitaxy at 400 °C. At this temperature, the Au particles alloy with Ga to form liquid droplets. Upon As supersaturation of the droplets, GaAs NWs of hexagonal shape crystallize under the droplets. The boundaries of this system consist of the NW-catalyst interface, the NW sidewalls, and the surface of the liquid catalyst particle. We examine the formation of the WZ phase. The sidewalls of the NWs are {11-20} facets, and the hexagon sides are ⟨10-10⟩ directions. We first present an atomically resolved growth observation in a ⟨11-20⟩ zone axis. The electron beam is then parallel to the LS interface, and the atomic columns parallel to the beam produce a strong contrast.

Nevertheless, the observation conditions adopted in these studies, with the electron beam parallel to the LS interface, provide an incomplete picture of ML formation and progression. Here, we present in addition bird’s eye views of growing NWs which reveal essential complementary information. A two-dimensional projection of the growing ML is visualized, from the early stage of formation to ML completion. We confirm that WZ layers start from the periphery of the NW top facet, and we image, analyze, and model the progression of the step within this hexagonal perimeter. Relevant edge energies are extracted. This leads to a better understanding of the formation of the nanocrystal and ultimately to a better control of its structure.

Reference :

Atomic step flow on a nanofacet
J.-C. Harmand, G. Patriarche, F. Glas, F. Panciera, I. Florea, J.-L. Maurice, L. Travers et Y. Ollivier; Physical Review Letters, 121, 166101 (2018)
DOI : 10.1103/PhysRevLett.121.166101