In Situ TEM Study of Straining of Free Standing Nickel Thin Films

2000 ◽  
Vol 6 (S2) ◽  
pp. 464-465
Author(s):  
W.-A. Chiou ◽  
R. Mitra
Keyword(s):  
Ultrafine Grain ◽  
In Situ Tem ◽  
Metallic Films ◽  
Free Standing ◽  
Nickel Thin Films ◽  
Ultrafine Grain Size ◽  
Thin Nickel ◽  
Unique Method ◽  
Bulk Nanocrystalline

In situ dynamic experiments in the TEM provide a powerful and unique method of investigating materials, when they are subjected to different environments or treatments. Study of plastic deformation mechanisms of free standing thin metallic films have evoked strong research interest in recent years. In the past, free standing thin metallic films have been tested in tension, where the tensile properties were measured and compared with those of bulk samples. Certain other studies dealt with metallic films attached to the substrate, where the deformation was introduced by thermal cycling or mechanical straining. The deformaion of bulk nanocrystalline samples has also been extensively studied recently. However, few publications have documented in situ straining of free standing metallic films with ultrafine grain size. In this study, an in situ straining stage was employed in the TEM to deform a free standing thin nickel film with grain sizes in submicron and nanocrystalline range, and the goal was to observe the microstructural response to deformation.

In-Situ TEM Study of Plastic Stress Relaxation Mechanisms and Interface Effects in Metallic Films

2005 ◽  
Vol 875 ◽  
Author(s):  
Marc Legros ◽  
Gerhard Dehm ◽  
T. John Balk
Keyword(s):  
Thin Films ◽  
High Strength ◽  
Dislocation Motion ◽  
Dislocation Nucleation ◽  
Film Stress ◽  
In Situ Tem ◽  
Metallic Films ◽  
Cross Sectional ◽  
Thin Foils

AbstractTo investigate the origin of the high strength of thin films, in-situ cross-sectional TEM deformation experiments have been performed on several metallic films attached to rigid substrates. Thermal cycles, comparable to those performed using laser reflectometry, were applied to thin foils inside the TEM and dislocation motion was recorded dynamically on video. These observations can be directly compared to the current models of dislocation hardening in thin films. As expected, the role of interfaces is crucial, but, depending on their nature, they can attract or repel dislocations. When the film/interface holds off dislocations, experimental values of film stress match those predicted by the Nix-Freund model. In contrast, the attracting case leads to higher stresses that are not explained by this model. Two possible hardening scenarios are explored here. The first one assumes that the dislocation/interface attraction reduces dislocation mobility and thus increases the yield stress of the film. The second one focuses on the lack of dislocation nucleation processes in the case of attracting interfaces, even though a few sources have been observed in-situ.

In situ TEM Straining of Nanograined Al Films Strengthened with Al2O3 Nanoparticles

2010 ◽  
Vol 1262 ◽  
Author(s):  
Khalid Hattar ◽  
Blythe G. Clark ◽  
James A Knapp ◽  
David M Follstaedt ◽  
I. M. Robertson
Keyword(s):  
In Situ Tem ◽  
Al2o3 Nanoparticles ◽  
Particle Sizes ◽  
Free Standing ◽  
Active Deformation ◽  
Deformation And Failure ◽  
Annealing Conditions ◽  
Thermal Histories ◽  
Initial Results

AbstractGrowing interest in nanomaterials has raised many questions regarding the operating mechanisms active during the deformation and failure of nanoscale materials. To address this, a simple, effective in situ TEM straining technique was developed that provides direct detailed observations of the active deformation mechanisms at a length scale relevant to most nanomaterials. The capabilities of this new straining structure are highlighted with initial results in pulsed laser deposited (PLD) Al-Al2O3 thin films of uniform thickness. The Al-Al2O3 system was chosen for investigation, as the grain size can be tailored via deposition and annealing conditions and the active mechanisms in the binary system can be compared to previous studies in PLD Ni and evaporated Al films. PLD Al-Al2O3 free-standing films of various oxide concentrations and different thermal histories were produced and characterized in terms of average grain and particle sizes. Preliminary in situ TEM straining experiments show intergranular failure for films with 5 vol% Al2O3. Further work is in progress to explore and understand the active deformation and failure mechanisms, as well as the dependence of mechanisms on processing routes.

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 The potentials and challenges of electron microscopy in the study of atomic chains

2017 ◽  
Vol 78 (2) ◽  
pp. 20701
Author(s):  
Florian Banhart ◽  
Alessandro La Torre ◽  
Ferdaous Ben Romdhane ◽  
Ovidiu Cretu
Keyword(s):  
Electron Microscopy ◽  
Electrical Transport ◽  
In Situ Tem ◽  
Free Standing ◽  
One Dimensional ◽  
Resonant States ◽  
In Situ Experiments ◽  
Atomic Chains ◽  
Substantial Progress

The article is a brief review on the potential of transmission electron microscopy (TEM) in the investigation of atom chains which are the paradigm of a strictly one-dimensional material. After the progress of TEM in the study of new two-dimensional materials, microscopy of free-standing one-dimensional structures is a new challenge with its inherent potentials and difficulties. In-situ experiments in the TEM allowed, for the first time, to generate isolated atomic chains consisting of metals, carbon or boron nitride. Besides having delivered a solid proof for the existence of atomic chains, in-situ TEM studies also enabled us to measure the electrical properties of these fundamental linear structures. While ballistic quantum conductivity is observed in chains of metal atoms, electrical transport in chains of sp1-hybridized carbon is limited by resonant states and reflections at the contacts. Although substantial progress has been made in recent TEM studies of atom chains, fundamental questions have to be answered, concerning the structural stability of the chains, bonding states at the contacts, and the suitability for applications in nanotechnology.

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.

In situ TEM Observations of Grain Growth in Nanograined Thin Films

2004 ◽  
Vol 854 ◽  
Author(s):  
K. Hattar ◽  
J. Gregg ◽  
J. Han ◽  
T. Saif ◽  
I. M. Robertson
Keyword(s):  
Thin Films ◽  
Grain Growth ◽  
Elevated Temperatures ◽  
Critical Role ◽  
Grain Structure ◽  
In Situ Tem ◽  
Free Standing ◽  
Transmission Electron Microscopy Analysis ◽  
Cu Films

ABSTRACTIn situ transmission electron microscopy analysis is used to study the stability of nanograined and ultra-fine grained thin films at elevated temperatures. In the free-standing Au and Cu films, grain growth was dependent on annealing temperature and time with growth observed in both materials at temperatures greater than 373K. Both materials exhibited abnormal grain growth although it was more prevalent in Au than in Cu, which may be a consequence of pinning of the Cu grain boundaries by impurities. The formation and destruction of twins was observed to play a critical role in the grain growth, with the twins retarding the growth in gold, but not in Cu. In constrained Au films no grain growth was observed on annealing at temperatures below 636 K. At 636 K, the eutectic temperature, the microstructure transformed to the eutectic structure with the first stage being the annihilation of the grain structure.

An In-Situ Tem Study of the Dynamic Behavior of Domain Walls in a Free-Standing Lead Titanate Thin Film Under External Stress

1995 ◽  
Vol 404 ◽  
Author(s):  
S. B. Ren ◽  
C. J. Lu ◽  
H. M. Shen ◽  
Y. N. Wang
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Dynamic Behavior ◽  
Domain Walls ◽  
High Stress ◽  
Ferroelectric Thin Film ◽  
External Stress ◽  
In Situ Tem ◽  
Free Standing

AbstractThe evolution of domain structure with external stress in a free-standing PbTiO3 ferroelectric thin film of ˜100nm in thickness is observed by in-situ TEM technique. The thin film is composed of granular grains of ˜100nm in diameter, most of them appear to be single-domained whereas others are multi-domained showing domains of different sizes(5˜20nm). For some single-domained grains new domains appear during tension. For multi-domained grains, rearrangement of domain walls and coarsening of domains have been observed during tension. In many cases the domain walls disappear under high stress, i.e., a multi-domained grain changes into a single-domained grain. However, it is also observed that a large portion of single-domained grains appear not to respond to external stress. The dynamic behavior of domain walls in very thin ferroelectric thin films may help to understand the switching of these very thin films.

In situ TEM studies of irradiation effects for materials improvement

1991 ◽  
Vol 49 ◽  
pp. 452-453
Author(s):  
Charles W. Allen
Keyword(s):  
Nuclear Reactor ◽  
Austenitic Stainless Steels ◽  
High Energy ◽  
Point Of View ◽  
In Situ Tem ◽  
Irradiation Effects ◽  
Tem Analysis ◽  
Radiation Induced ◽  
Analytical Tools

Irradiation effects studies employing TEMs as analytical tools have been conducted for almost as many years as materials people have done TEM, motivated largely by materials needs for nuclear reactor development. Such studies have focussed on the behavior both of nuclear fuels and of materials for other reactor components which are subjected to radiation-induced degradation. Especially in the 1950s and 60s, post-irradiation TEM analysis may have been coupled to in situ (in reactor or in pile) experiments (e.g., irradiation-induced creep experiments of austenitic stainless steels). Although necessary from a technological point of view, such experiments are difficult to instrument (measure strain dynamically, e.g.) and control (temperature, e.g.) and require months or even years to perform in a nuclear reactor or in a spallation neutron source. Consequently, methods were sought for simulation of neutroninduced radiation damage of materials, the simulations employing other forms of radiation; in the case of metals and alloys, high energy electrons and high energy ions.

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