Development of Quantitative in Situ Transmission Electron Microscopy for Nanoindentation and Cold-field Emission PDF Download
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Author: Ludvig de Knoop
Publisher:
ISBN:
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Languages : en
Pages : 0
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Book Description
This thesis has focused on the development of quantitative in situ transmission electron microscopy (TEM) techniques. We have used a special nano-probe sample holder, which allows local electrical biasing and micro-mechanical testing. The finite element method (FEM) was used to compare models with the experimental results. In addition to conventional imaging techniques, electron holography has been used to measure electric fields and strains. The first part addresses cold-field emission from a carbon cone nanotip (CCnT). This novel type of carbon structure may present an alternative to W-based cold-field emission sources, which are used in the most advanced electron guns today. When a sufficiently strong electric field is applied to the CCnT, electrons can tunnel through the energy barrier with the vacuum, which corresponds to the phenomenon of cold-field emission. Using electron holography and FEM, a quantified value of the local electric field at the onset of field emission was found (2.5 V/nm). Combining this with one of the Fowler-Nordheim equations, the exit work function of the CCnT was determined to be 4.8±0.3 eV. The number of charges on the CCnT before and after the onset of field emission was also measured. The second part focuses on the plastic deformation of Al thin films to test dislocation-interface interactions. A dislocation close to an interface with a stiffer material should be repelled by it. Here, we find to the contrary that dislocations moving towards the oxidized interface are absorbed, even at room temperature. The stress was derived from a combination of load-cell measurements and FEM calculations. Finally, preliminary experiments to combine in situ indentation and dark-field electron holography are reported.
Author: Ludvig de Knoop
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Book Description
This thesis has focused on the development of quantitative in situ transmission electron microscopy (TEM) techniques. We have used a special nano-probe sample holder, which allows local electrical biasing and micro-mechanical testing. The finite element method (FEM) was used to compare models with the experimental results. In addition to conventional imaging techniques, electron holography has been used to measure electric fields and strains. The first part addresses cold-field emission from a carbon cone nanotip (CCnT). This novel type of carbon structure may present an alternative to W-based cold-field emission sources, which are used in the most advanced electron guns today. When a sufficiently strong electric field is applied to the CCnT, electrons can tunnel through the energy barrier with the vacuum, which corresponds to the phenomenon of cold-field emission. Using electron holography and FEM, a quantified value of the local electric field at the onset of field emission was found (2.5 V/nm). Combining this with one of the Fowler-Nordheim equations, the exit work function of the CCnT was determined to be 4.8±0.3 eV. The number of charges on the CCnT before and after the onset of field emission was also measured. The second part focuses on the plastic deformation of Al thin films to test dislocation-interface interactions. A dislocation close to an interface with a stiffer material should be repelled by it. Here, we find to the contrary that dislocations moving towards the oxidized interface are absorbed, even at room temperature. The stress was derived from a combination of load-cell measurements and FEM calculations. Finally, preliminary experiments to combine in situ indentation and dark-field electron holography are reported.
Author: Nicolas Brodusch
Publisher: Springer
ISBN: 9811044333
Category : Technology & Engineering
Languages : en
Pages : 143
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Book Description
This book highlights what is now achievable in terms of materials characterization with the new generation of cold-field emission scanning electron microscopes applied to real materials at high spatial resolution. It discusses advanced scanning electron microscopes/scanning- transmission electron microscopes (SEM/STEM), simulation and post-processing techniques at high spatial resolution in the fields of nanomaterials, metallurgy, geology, and more. These microscopes now offer improved performance at very low landing voltage and high -beam probe current stability, combined with a routine transmission mode capability that can compete with the (scanning-) transmission electron microscopes (STEM/-TEM) historically run at higher beam accelerating voltage
Author:
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ISBN:
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Languages : en
Pages : 5
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Book Description
In-situ transmission electron microscopy is an established experimental technique that permits direct observation of the dynamics and mechanisms of dislocation motion and deformation behavior. In this paper, we detail the development of a novel specimen goniometer that allows real time observations of the mechanical response of materials to indentation loads. The technology of the scanning tunneling microscope is adopted to allow nanometer scale positioning of a sharp, conductive diamond tip onto the edge of an electron transparent sample. This allows application of loads to nanometer-scale material volumes couple with simultaneous imaging of the material response. The emphasis in this paper is experimental and descriptive, with particular attention given to sample geometry and other technical requirements. Examples of the deformation of aluminum and titanium carbide as well as the fracture of silicon will be presented.
Author: Litao Sun
Publisher: Springer Nature
ISBN: 9811968454
Category : Technology & Engineering
Languages : en
Pages : 378
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Book Description
This book focuses on in-situ transmission electron microscopy (TEM), an investigatory technique used to observe a sample’s response to a given stimulus (including electron irradiation, thermal excitation, mechanical force, optical excitation, electric and magnetic fields) at the nanoscale in real time. The book introduces readers to the technical strategy behind the in-situ technique and its developments. It reviews the research frontiers of using in-situ TEM in energy conversion and storage, catalysis, nanomaterials synthesis, nanoelectronics, etc. Furthermore, it discusses the future prospects for in-situ TEM. The book offers a valuable guide for all undergraduate and graduate students who are interested in TEM characterization technology. It also serves as a reference source on cutting-edge in-situ techniques for researchers and engineers.
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Category :
Languages : en
Pages : 5
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Book Description
This paper highlights future developments in the field of in-situ transmission electron microscopy, as applied specifically to the issues of deformation in thin films and nanostructured materials. Emphasis is place on the forthcoming technical advances that will aid in extraction of improved quantitative experimental data using this technique.
Author: Alain Claverie
Publisher: John Wiley & Sons
ISBN: 1118579054
Category : Technology & Engineering
Languages : en
Pages : 280
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Book Description
Today, the availability of bright and highly coherent electron sources and sensitive detectors has radically changed the type and quality of the information which can be obtained by transmission electron microscopy (TEM). TEMs are now present in large numbers not only in academia, but also in industrial research centers and fabs. This book presents in a simple and practical way the new quantitative techniques based on TEM which have recently been invented or developed to address most of the main challenging issues scientists and process engineers have to face to develop or optimize semiconductor layers and devices. Several of these techniques are based on electron holography; others take advantage of the possibility of focusing intense beams within nanoprobes. Strain measurements and mappings, dopant activation and segregation, interfacial reactions at the nanoscale, defect identification and specimen preparation by FIB are among the topics presented in this book. After a brief presentation of the underlying theory, each technique is illustrated through examples from the lab or fab.
Author: Andrew Murphy Minor
Publisher:
ISBN:
Category :
Languages : en
Pages : 246
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Book Description
Author: Renu Sharma
Publisher: John Wiley & Sons
ISBN: 3527347984
Category : Science
Languages : en
Pages : 389
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Book Description
In-Situ Transmission Electron Microscopy Experiments Design and execute cutting-edge experiments with transmission electron microscopy using this essential guide In-situ microscopy is a recently-discovered and rapidly-developing approach to transmission electron microscopy (TEM) that allows for the study of atomic and/or molecular changes and processes while they are in progress. Experimental specimens are subjected to stimuli that replicate near real-world conditions and their effects are observed at a previously unprecedented scale. Though in-situ microscopy is becoming an increasingly important approach to TEM, there are no current texts combining an up-to-date overview of this cutting-edge set of techniques with the experience of in-situ TEM professionals. In-Situ Transmission Electron Microscopy Experiments meets this need with a work that synthesizes the collective experience of myriad collaborators. It constitutes a comprehensive guide for planning and performing in-situ TEM measurements, incorporating both fundamental principles and novel techniques. Its combination of technical detail and practical how-to advice makes it an indispensable introduction to this area of research. In-Situ Transmission Electron Microscopy Experiments readers will also find: Coverage of the entire experimental process, from method selection to experiment design to measurement and data analysis Detailed treatment of multimodal and correlative microscopy, data processing and machine learning, and more Discussion of future challenges and opportunities facing this field of research In-Situ Transmission Electron Microscopy Experiments is essential for graduate students, post-doctoral fellows, and early career researchers entering the field of in-situ TEM.
Author: Joon Hwan Lee
Publisher:
ISBN:
Category :
Languages : en
Pages : 226
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Book Description
With the recent development of in situ transmission electron microscopy (TEM) characterization techniques, the real time study of property-structure correlations in nanomaterials becomes possible. This dissertation reports the direct observations of deformation behavior of Al2O3-ZrO2-MgAl2O4 (AZM) bulk ceramic nanocomposites, strengthening mechanism of twins in YBa2Cu3O7−x (YBCO) thin film, work hardening event in nanocrystalline nickel and deformation of 2wt% Al doped ZnO (AZO) thin film with nanorod structures using the in situ TEM nanoindentation tool. The combined in situ movies with quantitative loading-unloading curves reveal the deformation mechanism of the above nanomaterial systems. At room temperature, in situ dynamic deformation studies show that the AZM nanocomposites undergo the deformation mainly through the grain-boundary sliding and rotation of small grains, i.e., ZrO2 grains, and some of the large grains, i.e., MgAl2O4 grains. We observed both plastic and elastic deformations in different sample regions in these multi-phase ceramic nanocomposites at room temperature. Both ex situ (conventional) and in situ nanoindentation were conducted to reveal the deformation of YBCO films from the directions perpendicular and parallel to the twin interfaces. Hardness measured perpendicular to twin interfaces is ~50% and 40% higher than that measured parallel to twin interfaces, by ex situ and in situ, respectively. By using an in situ nanoindentation tool inside TEM, dynamic work hardening event in nanocrystalline nickel was directly observed. During stain hardening stage, abundant Lomer-Cottrell (L-C) locks formed both within nanograins and against twin boundaries. Two major mechanisms were identified during interactions between L-C locks and twin boundaries. Quantitative nanoindentation experiments recorded during in situ experiments show an increase of yield strength from 1.64 to 2.29 GPa during multiple loading-unloading cycles. In situ TEM nanoindentation has been conducted to explore the size dependent deformation behavior of two different types (type I: ~ 0.51 of width/length ratio and type II: ~ 088 ratio) of AZO nanorods. During the indentation on type I nanord structure, annihilation of defects has been observed which is caused by limitation of the defect activities by relatively small size of the width. On the other hand, type II nanorod shows dislocation activities which enhanced the grain rotation under the external force applied on more isotropic direction through type II nanorod. The electronic version of this dissertation is accessible from http://hdl.handle.net/1969.1/148150
Author: Giuseppe Mario Caruso (docteur en physique).)
Publisher:
ISBN:
Category :
Languages : en
Pages : 195
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Book Description
The investigation of the physics of nanoscale systems ideally requires atomic spatial resolution and femtosecond time-resolution. Ultrafast Transmission Electron Microscopy (UTEM) combining subpicosecond temporal resolution and nanometer spatial resolution has recently emerged as a unique tool with unprecedented spatio-temporal resolutions. However, the performances of the first UTEMs were limited by the brightness of the photocathodes used as ultrafast electron source. In this context, it was soon realized that UTEMs relying on laser-driven electron sources based on nanoscale emitters would overcome this limitation. The aim of this thesis is to report the development of an ultrafast Transmission Electron Microscope based on a cold field emission source, which can operate either in DC or ultrafast mode. Electron emission from a tungsten nanotip is triggered by femtosecond laser pulses, which are tightly focused by optical components integrated inside a cold-field emission source close to the cathode. The measured brightness is the largest reported so far for UTEMs. Combining this new high brightness source with an injection/Cathodoluminescence system, composed of a parabolic mirror placed above the sample holder, the UTEM can be used to perform time-resolved ultrafast pump-probe TEM experiments. The possibilities of such an instrument for ultrafast imaging, diffraction, electron holography and spectroscopy are presented. Particular attention has been paid on applications in nano-optics. In particular, Electron Energy Gain Spectroscopy (EEGS) allows to investigate the optical excitations of nanosystems in the energy domain. The ability to easily synchronize ultrashort free electron pulses with the optical excitation of the sample in UTEMs is essential for the observation of strongly nonlinear electron/photon interactions. These experiments will enable us to characterize the spectro-temporal properties of the ultrashort electron beam. Off-axis electron holography performed with ultrafast electron pulses are finally discussed. The electron dose in the specimen plane is considerably reduced due to the low repetition rate of the electron pulse train. This peculiar property of ultrafast FE-TEMs implies that ultrafast holograms are acquired in low-dose-like conditions. As a consequence, the experimental parameters commonly used for the acquisition of off-axis electron holograms with conventional TEMs cannot be directly implemented in the ultrafast mode. Experimental studies were performed to find the optimum conditions for ultrafast off-axis electron holography. Influence of the dose, the coherence length of the source, the illumination condition and the instrument instabilities have been addressed.
