scholarly journals In Situ Study of Deformation Mechanisms in Sputtered Free-Standing Nanocrystalline Nickel Films

2004 ◽  
Vol 19 (4) ◽  
pp. 1029-1037 ◽  
Author(s):  
R. Mitra ◽  
A. Chiou ◽  
J.R. Weertman
Keyword(s):  
Deformation Mechanisms ◽  
Free Standing ◽  
Ample Evidence ◽  
Nickel Films ◽  
Major Mechanism ◽  
Transmission Electron ◽  
Grain Size Distributions ◽  
Bulk Nanocrystalline ◽  
Parallel Arrays

Nickel films of 1.5–10-μm thickness, produced by dc magnetron sputtering and with disperse grain size distributions peaking in the 30–60-nm range, were subject to in situ tensile straining in a transmission electron microscope. The deformation was stopped frequently, while keeping the load applied, for transmission electron microscopy observation of the internal structure. Contrast changes occurred in many of the grains between strain increments. Ample evidence was seen of dislocation activity, which appears to be the major mechanism for deformation of the samples. Dislocations were seen in grains as small as 20 nm. Parallel arrays of roughly equally spaced dislocations were observed, spaced about 5–10-nm apart. Intergranular nanovoids were found to form and grow with accompanying strain relief in neighboring grains. The results of the current study are generally consistent with previous in situ investigations and contribute to the understanding of deformation mechanisms in free-standing thin films, which may differ somewhat from those in bulk nanocrystalline materials or in films attached to a substrate.

Mechanisms of Grain Growth in Free-Standing Nanograined Gold Thin Films

2005 ◽  
Vol 907 ◽  
Author(s):  
J. A. Gregg ◽  
K Hattar ◽  
C H Lei ◽  
I M Robertson
Keyword(s):  
Thin Films ◽  
Grain Growth ◽  
Structural Changes ◽  
Dislocation Slip ◽  
Free Standing ◽  
Transmission Electron ◽  
Enhanced Properties ◽  
Gold Thin Films ◽  
Annealing Experiments

AbstractRetention of the enhanced properties reported for nanograined metallic systems requires that the nanostructure be insensitive to temperature and deformation. In situ transmission electron microscopy annealing experiments were employed to investigate the structural changes associated with the formation of micron-sized grains in nanograined evaporated gold thin films. This abnormal grain growth occurs randomly throughout the film. Twinning but not dislocation slip occurs in the growing grains until the grain size is in the hundreds of nanometer range. The twins appear to hinder growth and for grain growth to continue the twins must either be annihilated or be able to grow with the grain concurrently.

Fabrication and In Situ Transmission Electron Microscope Characterization of Free-Standing Graphene Nanoribbon Devices

ACS Nano ◽  
2016 ◽  
Vol 10 (1) ◽  
pp. 1475-1480 ◽  
Author(s):  
Qing Wang ◽  
Ryo Kitaura ◽  
Shoji Suzuki ◽  
Yuhei Miyauchi ◽  
Kazunari Matsuda ◽  
...  
Keyword(s):  
Electron Microscope ◽  
Transmission Electron Microscope ◽  
Graphene Nanoribbon ◽  
Free Standing ◽  
Transmission Electron

In-Situ UHV TEM Investigations of the Initial Stages of Cu(001) Oxidation

1997 ◽  
Vol 3 (S2) ◽  
pp. 583-584
Author(s):  
J. C. Yang ◽  
M. Yeadon ◽  
B. Kolasa ◽  
J. M. Gibson
Keyword(s):  
High Vacuum ◽  
Copper Film ◽  
Ultra High Vacuum ◽  
Native Oxide ◽  
In Situ Tem ◽  
Face Centered Cubic ◽  
Free Standing ◽  
Transmission Electron ◽  
Face Centered

We studied the beginning oxidation stage of a model metal system by in-situ transmission electron microscopy (TEM) in order to gain insights into the initial kinetics of oxidation. In-situ TEM experiments can distinguish between nucleation and growth since individual oxide islands are imaged. We chose to investigate Cu, since it is a simple face-centered cubic metal. Also, Cu is a highly promising metal interconnect material because of its low resistivity and good electromigration properties as compared to Al.Single crystal -1000Å 99.999% purity copper films were grown on irradiated NaCl in an UHV e-beam evaporator system. The free-standing copper film was placed on a specially designed holder, which permits resistive heating of the sample. The microscope used for this experiment is a modified ultra-high vacuum, with base pressure of 10−9 torr, JEOL200CX, operated at l00kV. To remove the native oxide formed during exposure in air, the Cu film was annealed at ∼350°C

scholarly journals Anti-twinning in nanoscale tungsten

2020 ◽  
Vol 6 (23) ◽  
pp. eaay2792
Author(s):  
Jiangwei Wang ◽  
Zhi Zeng ◽  
Minru Wen ◽  
Qiannan Wang ◽  
Dengke Chen ◽  
...  
Keyword(s):  
Nucleation And Growth ◽  
Shear Displacement ◽  
Atomic Scale ◽  
Deformation Mechanisms ◽  
Body Centered Cubic ◽  
Plastic Shear ◽  
Transmission Electron ◽  
20 Nm ◽  
Scale Shear

Nanomaterials often surprise us with unexpected phenomena. Here, we report a discovery of the anti-twinning deformation, previously thought impossible, in nanoscale body-centered cubic (BCC) tungsten crystals. By conducting in situ transmission electron microscopy nanomechanical testing, we observed the nucleation and growth of anti-twins in tungsten nanowires with diameters less than about 20 nm. During anti-twinning, a shear displacement of 1/3〈111〉 occurs on every successive {112} plane, in contrast to an opposite shear displacement of 1/6〈1¯1¯1¯〉 by ordinary twinning. This asymmetry in the atomic-scale shear pathway leads to a much higher resistance to anti-twinning than ordinary twinning. However, anti-twinning can become active in nanosized BCC crystals under ultrahigh stresses, due to the limited number of plastic shear carriers in small crystal volumes. Our finding of the anti-twinning phenomenon has implications for harnessing unconventional deformation mechanisms to achieve high mechanical preformation by nanomaterials.

scholarly journals In situ formation of 1D nanostructures from ceria nanoparticle dispersions by liquid cell TEM irradiation

2019 ◽  
Vol 55 (7) ◽  
pp. 2815-2825 ◽  
Author(s):  
M. S. A. Asghar ◽  
B. J. Inkson ◽  
G. Möbus
Keyword(s):  
Cerium Oxide Nanoparticles ◽  
Oxide Nanoparticles ◽  
Free Standing ◽  
1D Nanostructures ◽  
Radical Concentration ◽  
Nanoparticle Dispersions ◽  
Transmission Electron ◽  
Liquid Cell ◽  
In Situ Formation

Abstract Deliberate electron irradiation of cerium oxide nanoparticles in water is used to trigger chemical reactions in a liquid cell transmission electron microscope. Formation of nanorods and nanoneedles is observed starting from predominantly octahedral shape nanoparticles. Detailed morphologies found include free-standing needles, needles connected to specific octahedral ceria facets and star-shaped multi-needle patterns. It is found that rod-axis orientations and crystallographic directions are aligned. It is suggested that high ion and radical concentration of radiolysed water dissolves layers of the original CeO2 particles which re-arrange as needles in the direction of energetically preferred facets.

scholarly journals Decorrelated Dislocation Movement in the γ-Matrix Channels of a Ni-Based Superalloy: Experiment and Dislocation Dynamics Simulation

2011 ◽  
Vol 278 ◽  
pp. 13-18
Author(s):  
Florence Pettinari-Sturmel ◽  
Joël Douin ◽  
Didier Locq ◽  
Pierre Caron ◽  
Armand Coujou
Keyword(s):  
Partial Dislocation ◽  
Dislocation Dynamics ◽  
Dynamics Simulation ◽  
Deformation Mechanisms ◽  
Narrow Channels ◽  
Microscopic Scale ◽  
Transmission Electron ◽  
Dislocation Movement ◽  
Low Strain Rate

The mechanical behavior of the polycrystalline NR3 Ni-based superalloy has been investigated at the microscopic scale. The elementary deformation mechanisms have been analyzed using transmission electron microscope observations as well as in situ straining experiments. Under low stress and relatively low strain rate conditions, a large variety of shearing micromechanisms has been observed depending on the local microstructure and the local effective stress. The influence of the smallest precipitates on the creep behavior has been enlightened: they induce narrow channels which act as obstacle for the movement of the dislocations. In the case of the narrowest channel, the deformation can operate by the propagation of Shockley dislocations or else, by the only propagation of the leading partial resulting from the partial dislocation decorrelation. The occurrence of the observed micromechanisms has been quantitatively analyzed using a nodal dislocation dynamics simulation.

In Situ High Voltage Electron Microscopy Observations of Deformation and Fracture in Multilayered Materials

1995 ◽  
Vol 404 ◽  
Author(s):  
M. A. Wall ◽  
T. W. Barbee ◽  
T. P. Weihs
Keyword(s):  
Crack Nucleation ◽  
Free Standing ◽  
Cross Sectional ◽  
High Voltage Electron Microscopy ◽  
Voltage Electron ◽  
Transmission Electron ◽  
Deformation And Fracture ◽  
Gauge Section ◽  
Multilayered Materials

AbstractA novel, in situ transmission electron microcopy technique for the direct observation of deformation and fracture in multilayered materials oriented in cross-section is reviewed. Cross-sectional tensile specimens were prepared from thick, free-standing, Cu/Zr and Al/Ti multilayered foils. These tensile specimens contain a micro-gauge section, thus predetermining the location at which dislocation activity and crack nucleation and growth can be observed at high magnifications in the transmission electron microscope. The results from these experiments are unique and cannot be realized by any other technique. These observations will aid us in our understanding of the micromechanisms of deformation and fracture in multilayered materials.

Understanding the graphitization and growth of free-standing nanocrystalline graphene using in situ transmission electron microscopy

Nanoscale ◽  
2017 ◽  
Vol 9 (35) ◽  
pp. 12835-12842 ◽  
Author(s):  
C. N. Shyam Kumar ◽  
Venkata Sai Kiran Chakravadhanula ◽  
Adnan Riaz ◽  
Simone Dehm ◽  
Di Wang ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Thin Films ◽  
Transmission Electron Microscopy ◽  
Domain Growth ◽  
Free Standing ◽  
Tem Analysis ◽  
Thermally Induced ◽  
Transmission Electron

In situ TEM analysis of the thermally induced graphitization and domain growth of free-standing nanocrystalline graphene thin films.

In situ Atmospheric Transmission Electron Microscopy of Catalytic Nanomaterials

MRS Advances ◽  
2018 ◽  
Vol 3 (39) ◽  
pp. 2297-2303 ◽  
Author(s):  
Sheng Dai ◽  
Wenpei Gao ◽  
George W. Graham ◽  
Xiaoqing Pan
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Reduction Reaction ◽  
In Situ Observation ◽  
Atmospheric Transmission ◽  
Free Standing ◽  
Gaseous Reaction ◽  
Transmission Electron ◽  
Catalyst Systems

AbstractSignificant developments in micro-electrical-mechanical systems (MEMS)-based devices for use in transmission electron microscopy (TEM) sample holders have recently led to the commercialization of windowed gas cells that now enable the atomic-resolution visualization of phenomena occurring during gas-solid interactions at atmospheric pressure. In situ atmospheric TEM study provides unique information that is beneficial to correlating the structure-properties relationship of catalytic nanomaterials, particularly under realistic gaseous reaction conditions. In this paper, we illustrate the capability of this novel in situ device as applied to our study of two catalyst systems: (1) In situ kinetic growth of free standing Pt nanowires as active catalysts toward oxygen reduction reaction (ORR); (2) In situ observation of facet-dependent oxidation of another promising ORR catalyst, Pt3Co nanoparticles.

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