In situ REM imaging of surface processes on ceramic bulk crystals from 300 to 1670 K in a conventional TEM

1991 ◽  
Vol 49 ◽  
pp. 660-661
Author(s):  
Z. L. Wang ◽  
J. Bentley
Keyword(s):  
High Temperatures ◽  
Image Resolution ◽  
Atomic Processes ◽  
Crystal Surfaces ◽  
Beam Radiation ◽  
Surface Areas ◽  
Transmission Electron ◽  
Reflection Electron Microscopy ◽  
Gas Reactions

Studying the behavior of surfaces at high temperatures is of great importance for understanding the properties of ceramics and associated surface-gas reactions. Atomic processes occurring on bulk crystal surfaces at high temperatures can be recorded by reflection electron microscopy (REM) in a conventional transmission electron microscope (TEM) with relatively high resolution, because REM is especially sensitive to atomic-height steps.Improved REM image resolution with a FEG: Cleaved surfaces of a-alumina (012) exhibit atomic flatness with steps of height about 5 Å, determined by reference to a screw (or near screw) dislocation with a presumed Burgers vector of b = (1/3)<012> (see Fig. 1). Steps of heights less than about 0.8 Å can be clearly resolved only with a field emission gun (FEG) (Fig. 2). The small steps are formed by the surface oscillating between the closely packed O and Al stacking layers. The bands of dark contrast (Fig. 2b) are the result of beam radiation damage to surface areas initially terminated with O ions.

Growth of Niobium Films at High Temperatures on Sapphire

1996 ◽  
Vol 440 ◽  
Author(s):  
T. Wagner
Keyword(s):  
High Temperatures ◽  
Basal Plane ◽  
Misfit Strain ◽  
High Energy ◽  
Total Density ◽  
Initial Growth ◽  
Island Size ◽  
Transmission Electron ◽  
Orientation Density

AbstractThe growth and microstructural evolution of Nb thin films on the basal plane of α-Al2O3 were studied at different growth temperatures. The influence of island orientation, density, and misfit strain energy on the growth behavior of Nb films on (0001)α-Al2O3 at high temperatures has been investigated. The films were grown by MBE at 900°C and 1100°C. At these temperatures the Nb grows in the Volmer-Weber growth mode on the basal plane. In-situ reflection high energy electron diffraction (RHEED), Auger electron spectroscopy (AES) and transmission electron microscopy (TEM) investigations revealed that in the initial growth stage, Nb nuclei with different epitaxial orientations were formed. This leads to different orientations of thicker Nb films at different growth temperatures. At a growth temperature of 900°C the Nb{111} planes are parallel to the sapphire basal plane whereas at 1100°C Nb grows with the {110) planes parallel to the basal plane of sapphire. The formation of two different epitaxial orientations of thick Nb films can only be explained by considering both the change in the total density of Nb islands with temperature and the influence of island size on their total energy.

To-and-Fro Motion of W5Si3 on a β-Si3N4 Substrate at Elevated Temperatures

2002 ◽  
Vol 8 (1) ◽  
pp. 16-20 ◽  
Author(s):  
S. Arai ◽  
K. Suzuki ◽  
H. Saka
Keyword(s):  
Electron Microscope ◽  
High Temperatures ◽  
Transmission Electron Microscope ◽  
Elevated Temperatures ◽  
Fine Particles ◽  
Transmission Electron ◽  
In Situ Heating

Behavior of fine crystalline particles of W5Si3 on a β-Si3N4 substrate at high temperatures was observed by an in situ heating experiment in a transmission electron microscope. Some of the fine particles of W5Si3 moved in a to-and-fro manner.

Reflection Electron Microscopy and Diffraction from Crystal Surfaces

1983 ◽  
Vol 31 ◽  
Author(s):  
J.M. Cowley
Keyword(s):  
Electron Microscopy ◽  
Surface Structure ◽  
Crystal Surfaces ◽  
Local Composition ◽  
Surface Steps ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Reflection Electron Microscopy ◽  
Electron Microscopes ◽  
Geometric Effects

ABSTRACTThe recent revival of techniques for the imaging of crystal surfaces, using electrons forward-scattered in the RHEED mode and employing modern electron microscopes, has lead to the introduction of valuable new methods for the study of surface structure. Either fixed beam or scanning transmission electron microscopy (STEM) instruments may be used and in each case a lateral resolution of 10Å or better is possible. Simple theoretical treatments suggest that the contrast from surface steps may be attributed to a combination of phase-contrast, diffraction contrast and geometric effects. With a STEM instrument the image information can be combined with information on the local composition and crystal structure by use of microanalysis and microdiffraction techniques. Examples of applications include studies of the surface structure of metals, semiconductors and oxides, and the surface reactions.

High-Temperature In Situ Straining Experiments in the High-Voltage Electron Microscope

1998 ◽  
Vol 4 (3) ◽  
pp. 226-234 ◽  
Author(s):  
Ulrich Messerschmidt ◽  
Dietmar Baither ◽  
Martin Bartsch ◽  
Bernd Baufeld ◽  
Bert Geyer ◽  
...  
Keyword(s):  
High Temperature ◽  
High Temperatures ◽  
Oxide Dispersion Strengthened ◽  
Voltage Electron ◽  
Dislocation Plasticity ◽  
Transmission Electron ◽  
Macroscopic Deformation ◽  
Oxide Particles ◽  
Short Time

Design rules are described here for high-temperature straining stages for transmission electron microscopy. Temperatures above 1000°C can be attained by electron bombardment of the specimen grips. Thermal equilibrium can be reached in a short time by carrying off the heat by water cooling. Some applications of this stage are described. Ferroelastic deformation was observed at 1150°C in t′ and partially stabilized zirconia, which changes the microstructure for successive dislocation plasticity. In the oxide-dispersion-strengthened alloy INCOLOY MA 956, dislocations are impeded by oxide particles and move smoothly between the particles. At high temperatures, both the resting and traveling times control the average dislocation velocity. In MoSi2 single crystals of a soft orientation, dislocations with 1/2〈111〉 Burgers vectors are created in localized sources and move on {110} planes in a viscous manner. The dislocations in Al-Pd-Mn single quasicrystals are oriented in preferred crystallographic directions and move in a viscous way as well. On the basis of in situ observations, conclusions are drawn for interpreting macroscopic deformation behavior at high temperatures.

High-Resolution EM of Colloidal Nanocrystal Growth Using Graphene Liquid Cells

Science ◽  
2012 ◽  
Vol 336 (6077) ◽  
pp. 61-64 ◽  
Author(s):  
Jong Min Yuk ◽  
Jungwon Park ◽  
Peter Ercius ◽  
Kwanpyo Kim ◽  
Daniel J. Hellebusch ◽  
...  
Keyword(s):  
Beam Radiation ◽  
Electron Beam Radiation ◽  
Nanocrystal Growth ◽  
Transmission Electron ◽  
Colloidal Platinum ◽  
New Type ◽  
Liquid Cell ◽  
Resolution Imaging ◽  
Site Selective

We introduce a new type of liquid cell for in situ transmission electron microscopy (TEM) based on entrapment of a liquid film between layers of graphene. The graphene liquid cell facilitates atomic-level resolution imaging while sustaining the most realistic liquid conditions achievable under electron-beam radiation. We employ this cell to explore the mechanism of colloidal platinum nanocrystal growth. Direct atomic-resolution imaging allows us to visualize critical steps in the process, including site-selective coalescence, structural reshaping after coalescence, and surface faceting.

Dynamics of In Cluster Growth During InP(110) Surface Dissociation Studied by in-situ Reflection Electron Microscopy

1995 ◽  
Vol 404 ◽  
Author(s):  
M. Gajdardziska-Josifovska ◽  
M. H. Malay ◽  
David J. Smith
Keyword(s):  
Electron Microscopy ◽  
Contact Angle ◽  
Annealing Process ◽  
Cluster Growth ◽  
Surface Cluster ◽  
Surface Steps ◽  
Transmission Electron ◽  
Annealing Effects ◽  
Reflection Electron Microscopy

AbstractAnnealing effects on InP (110) surfaces were observed in situ using a modified ultrahighvacuum transmission electron microscope equipped with a specimen heating holder. Reflection electron microscopy (REM) was used to record the dynamics of nucleation and growth of liquid In clusters at 650°C, following the desorption of P from the surface. These droplets showed no preference for nucleation at surface steps, and the steps appeared stationary throughout the annealing process. Two distinct types of In cluster growth rates and shape evolutions were detected. A model was developed to decouple height and length information in the REM images. Contact angle and volume above the InP(110) surface were calculated from the dynamic data. The change of contact angle with time provides evidence for sub-surface cluster etching.

In situ High Resolution TEM Observation of Solid-gas Reactions at High Temperatures

2007 ◽  
Vol 13 (S02) ◽  
Author(s):  
K Kishita ◽  
T Kamino ◽  
S Arai ◽  
K Kuroda ◽  
H Saka
Keyword(s):  
High Resolution ◽  
High Temperatures ◽  
High Resolution Tem ◽  
Gas Reactions

In situ REM study of indium particle evolution on InP(110) surfaces

1995 ◽  
Vol 53 ◽  
pp. 226-227
Author(s):  
M. Gajdardziska-Josifovska ◽  
M. H. Malay ◽  
David J. Smith
Keyword(s):  
Film Growth ◽  
Video Recording ◽  
Image Interpretation ◽  
Particle Sizes ◽  
Transmission Electron ◽  
Size Evolution ◽  
Surface Resonance ◽  
Projection Problem ◽  
Reflection Electron Microscopy

Reflection electron microscopy (REM) has been used by several groups for in situ studies of terrace and step dynamics induced by phase transformations, film growth, and surface electromigration. Real-time viewing and video-recording of these phenomena has become possible with the use of intensified TV cameras under surface resonance diffracting conditions. Recently we captured the dynamics of nucleation and growth of In particles on InP(l10) surfaces induced by thermal annealing in an ultrahigh-vacuum transmission electron microscope. In addition to the projection problem, also encountered in TEM, the REM image interpretation is further complicated by foreshortening effects. At present, there are no developed methods for measurement of particle sizes from REM images. This work quantifies the In particle shape and size evolution from in-situ REM experiments.Samples were prepared by cleavage of an undoped (001) InP wafer along the (110) crystallographic plane. The cleavage was performed in air, immediately before loading into a Philips 430ST HREM, modified for UHV operation and equipped with a single-tilt specimen heating holder.

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