scholarly journals Measuring Structural Heterogeneities in Metallic Glasses Using Transmission Electron Microscopy

Metals ◽  
2018 ◽  
Vol 8 (12) ◽  
pp. 1085 ◽  
Author(s):  
Lin Tian ◽  
Cynthia A. Volkert
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Metallic Glasses ◽  
Local Density ◽  
Temporal Correlations ◽  
Transmission Electron ◽  
Excellent Spatial Resolution ◽  
And Performance ◽  
The Stability

Local heterogeneities in the structure and properties of metallic glasses have recently been predicted by computer simulations and also observed in experiments. These heterogeneities are important in understanding the stability and performance of metallic glasses. Progress has been made in measuring heterogeneities in elastic properties and local density down to length scales of less than 10 nm. In this review, we focus on studies of structural and mechanical heterogeneities with emphasis on those achieved by transmission electron microscopy which has an excellent spatial resolution, multifunctional detection modes, as well as in-situ testing capabilities. We argue that the next important step in understanding the behavior of metallic glasses lies in understanding the spatial and temporal correlations between the various structural and mechanical heterogeneities.

Precipitation of Zr2Cu Stable Crystalline Phase from Zr70Cu27.5Rh2.5 Amorphous Alloy

2006 ◽  
Vol 979 ◽  
Author(s):  
David Cushman ◽  
Junji Saida ◽  
Chunfei Li
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Metallic Glasses ◽  
Crystalline Phase ◽  
Crystallization Process ◽  
Amorphous Matrix ◽  
Nucleation Process ◽  
Transmission Electron ◽  
The Stability ◽  
Icosahedral Quasicrystalline

AbstractThe crystallization process of Zr70Cu27.5Rh2.5 metallic glass was studied with Transmission Electron Microscopy (TEM). In contrast to previous studies where the precipitation of metastable icosahedral quasicrystalline (IQC) particles is of the interest, we designed the present work to focus on the nucleation process of the stable Zr2Cu crystalline phase. It has been found that the alloy consists of IQC particles distributed in amorphous matrix prior to the precipitation of the Zr2Cu stable crystalline phase and Zr2Cu nucleates from the amorphous matrix. The encounter of the IQC phase with Zr2Cu transforms the former into the latter so quickly that no interface between them was found in the present experiment. These insights provide the basis for a discussion of the stability of metallic glasses and the IQC particles.

Atomistic and dynamic structural characterizations in low-dimensional materials: recent applications of in situ transmission electron microscopy

Microscopy ◽  
2019 ◽  
Author(s):  
He Zheng ◽  
Fan Cao ◽  
Ligong Zhao ◽  
Renhui Jiang ◽  
Peili Zhao ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Atomic Scale ◽  
Transmission Electron ◽  
Indispensable Tool ◽  
And Performance ◽  
Low Dimensional ◽  
Low Dimensional Materials

Abstract In situ transmission electron microscopy has achieved remarkable advances for atomic-scale dynamic analysis in low-dimensional materials and become an indispensable tool in view of linking a material’s microstructure to its properties and performance. Here, accompanied with some cutting-edge researches worldwide, we briefly review our recent progress in dynamic atomistic characterization of low-dimensional materials under external mechanical stress, thermal excitations and electrical field. The electron beam irradiation effects in metals and metal oxides are also discussed. We conclude by discussing the likely future developments in this area.

Thermal stability of Nb thin films on sapphire

1996 ◽  
Vol 11 (5) ◽  
pp. 1255-1264 ◽  
Author(s):  
Thomas Wagner ◽  
Marko Lorenz ◽  
Manfred Rühle
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Orientation Relationship ◽  
High Energy ◽  
X Ray Diffraction ◽  
Model Study ◽  
Transmission Electron ◽  
The Stability ◽  
Thermal Stability Of

The Nb/α−Al2O3 system has been used as a model study for investigating the stability of different MBE grown epitaxial Nb films on α−Al2O3 substrates. The films were grown at 800 °C in ultrahigh vacuum. The growth process was monitored in situ by reflection high energy electron diffraction (RHEED). After deposition the structure of the film was investigated by x-ray diffraction (XRD) and conventional transmission electron microscopy (CTEM) which encompasses also selected area diffraction (SAD). Both techniques revealed the following orientation relationship between the Nb film and the α–Al2O3 substrate: (0001)α–Al2O3‖ (111)Nb; [2110]α–Al2O3‖ [110]Nb. The stability of the niobium films was investigated by annealing the Nb-film/α–Al2O3 system to temperatures up to 1500 °C for different periods of time. Surprisingly, the orientation relationship between the Nb film and the substrate changed to (0001)α–Al2O3‖ (110)Nb; [0110]α–Al2O3‖ [001]Nb. A model will be developed which shows that above a critical film thickness the growth orientation is metastable with respect to its crystallographic orientation. Furthermore, high resolution transmission electron microscopy (HREM) was performed to investigate the defect structure of the annealed Nb/α–Al2O3 interface.

scholarly journals Stability of a Bifunctional Cu-Based Core@Zeolite Shell Catalyst for Dimethyl Ether Synthesis Under Redox Conditions Studied by Environmental Transmission Electron Microscopy andIn SituX-Ray Ptychography

2017 ◽  
Vol 23 (3) ◽  
pp. 501-512 ◽  
Author(s):  
Sina Baier ◽  
Christian D. Damsgaard ◽  
Michael Klumpp ◽  
Juliane Reinhardt ◽  
Thomas Sheppard ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Dimethyl Ether ◽  
Core Shell ◽  
X Ray ◽  
Environmental Transmission ◽  
The Core ◽  
Transmission Electron ◽  
The Stability

AbstractWhen using bifunctional core@shell catalysts, the stability of both the shell and core–shell interface is crucial for catalytic applications. In the present study, we elucidate the stability of a CuO/ZnO/Al2O3@ZSM-5 core@shell material, used for one-stage synthesis of dimethyl ether from synthesis gas. The catalyst stability was studied in a hierarchical manner by complementary environmental transmission electron microscopy (ETEM), scanning electron microscopy (SEM) andin situhard X-ray ptychography with a specially designedin situcell. Both reductive activation and reoxidation were applied. The core–shell interface was found to be stable during reducing and oxidizing treatment at 250°C as observed by ETEM andin situX-ray ptychography, although strong changes occurred in the core on a 10 nm scale due to the reduction of copper oxide to metallic copper particles. At 350°C,in situX-ray ptychography indicated the occurrence of structural changes also on theµm scale, i.e. the core material and parts of the shell undergo restructuring. Nevertheless, the crucial core–shell interface required for full bifunctionality appeared to remain stable. This study demonstrates the potential of these correlativein situmicroscopy techniques for hierarchically designed catalysts.

Epitaxy and texture analysis of Bi-Sr-Ca-Cu-O thin films on (100) MgO using Transmission Electron Microscopy

1990 ◽  
Vol 48 (4) ◽  
pp. 68-69
Author(s):  
J. T. Sizemore ◽  
D. G. Schlom ◽  
Z. J. Chen ◽  
J. N. Eckstein ◽  
I. Bozovic ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Thin Films ◽  
Transmission Electron Microscopy ◽  
Critical Currents ◽  
Unit Cell ◽  
X Ray Diffraction ◽  
Cell Axis ◽  
Transmission Electron ◽  
Synthesis Procedure

Investigators observe large critical currents for superconducting thin films deposited epitaxially on single crystal substrates. The orientation of these films is often characterized by specifying the unit cell axis that is perpendicular to the substrate. This omits specifying the orientation of the other unit cell axes and grain boundary angles between grains of the thin film. Misorientation between grains of YBa2Cu3O7−δ decreases the critical current, even in those films that are c axis oriented. We presume that these results are similar for bismuth based superconductors and report the epitaxial orientations and textures observed in such films.Thin films of nominally Bi2Sr2CaCu2Ox were deposited on MgO using molecular beam epitaxy (MBE). These films were in situ grown (during growth oxygen was incorporated and the films were not oxygen post-annealed) and shuttering was used to encourage c axis growth. Other papers report the details of the synthesis procedure. The films were characterized using x-ray diffraction (XRD) and transmission electron microscopy (TEM).

Transmission Electron Microscopy of Epitaxial silicides grown by ultra high vacuum deposition

1989 ◽  
Vol 47 ◽  
pp. 462-463
Author(s):  
D. Loretto ◽  
J. M. Gibson ◽  
S. M. Yalisove
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Electron Diffraction ◽  
High Vacuum ◽  
High Energy ◽  
Energy Electron ◽  
Ultra High Vacuum ◽  
Ex Situ ◽  
Transmission Electron

The silicides CoSi2 and NiSi2 are both metallic with the fee flourite structure and lattice constants which are close to silicon (1.2% and 0.6% smaller at room temperature respectively) Consequently epitaxial cobalt and nickel disilicide can be grown on silicon. If these layers are formed by ultra high vacuum (UHV) deposition (also known as molecular beam epitaxy or MBE) their thickness can be controlled to within a few monolayers. Such ultrathin metal/silicon systems have many potential applications: for example electronic devices based on ballistic transport. They also provide a model system to study the properties of heterointerfaces. In this work we will discuss results obtained using in situ and ex situ transmission electron microscopy (TEM).In situ TEM is suited to the study of MBE growth for several reasons. It offers high spatial resolution and the ability to penetrate many monolayers of material. This is in contrast to the techniques which are usually employed for in situ measurements in MBE, for example low energy electron diffraction (LEED) and reflection high energy electron diffraction (RHEED), which are both sensitive to only a few monolayers at the surface.

Investigation of Switching Mechanism in HfO2-Based Oxide Resistive Memories by In-Situ Transmission Electron Microscopy and Electron Energy Loss Spectroscopy

2017 ◽  
Author(s):  
T. Dewolf ◽  
D. Cooper ◽  
N. Bernier ◽  
V. Delaye ◽  
A. Grenier ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Energy Loss ◽  
Electron Energy ◽  
Electron Energy Loss Spectroscopy ◽  
Hafnium Dioxide ◽  
Switching Mechanism ◽  
Transmission Electron ◽  
Electron Energy Loss

Abstract Forming and breaking a nanometer-sized conductive area are commonly accepted as the physical phenomenon involved in the switching mechanism of oxide resistive random access memories (OxRRAM). This study investigates a state-of-the-art OxRRAM device by in-situ transmission electron microscopy (TEM). Combining high spatial resolution obtained with a very small probe scanned over the area of interest of the sample and chemical analyses with electron energy loss spectroscopy, the local chemical state of the device can be compared before and after applying an electrical bias. This in-situ approach allows simultaneous TEM observation and memory cell operation. After the in-situ forming, a filamentary migration of titanium within the dielectric hafnium dioxide layer has been evidenced. This migration may be at the origin of the conductive path responsible for the low and high resistive states of the memory.

scholarly journals Fabrication of a liquid cell for in situ transmission electron microscopy

Microscopy ◽  
2020 ◽  
Author(s):  
Xiaoguang Li ◽  
Kazutaka Mitsuishi ◽  
Masaki Takeguchi
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Cost Effective ◽  
Production Method ◽  
Microscopy Imaging ◽  
Transmission Electron ◽  
In Situ Electron Microscopy ◽  
Liquid Cell ◽  
Si Wafer

Abstract Liquid cell transmission electron microscopy (LCTEM) enables imaging of dynamic processes in liquid with high spatial and temporal resolution. The widely used liquid cell (LC) consists of two stacking microchips with a thin wet sample sandwiched between them. The vertically overlapped electron-transparent membrane windows on the microchips provide passage for the electron beam. However, microchips with imprecise dimensions usually cause poor alignment of the windows and difficulty in acquiring high-quality images. In this study, we developed a new and efficient microchip fabrication process for LCTEM with a large viewing area (180 µm × 40 µm) and evaluated the resultant LC. The new positioning reference marks on the surface of the Si wafer dramatically improve the precision of dicing the wafer, making it possible to accurately align the windows on two stacking microchips. The precise alignment led to a liquid thickness of 125.6 nm close to the edge of the viewing area. The performance of our LC was demonstrated by in situ transmission electron microscopy imaging of the dynamic motions of 2-nm Pt particles. This versatile and cost-effective microchip production method can be used to fabricate other types of microchips for in situ electron microscopy.

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