Time-resolved high-resolution electron microscopy of structural stability in mgo clusters

1996 ◽  
Vol 54 ◽  
pp. 672-673
Author(s):  
T. Kizuka ◽  
N. Tanaka
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Magnesium Oxide ◽  
Structural Stability ◽  
High Resolution Electron Microscopy ◽  
Video Tape ◽  
Solid State Physics ◽  
Time Resolved ◽  
Resolution Electron ◽  
Structural And Functional Properties

Structure and stability of atomic clusters have been studied by time-resolved high-resolution electron microscopy (TRHREM). Typical examples are observations of structural fluctuation in gold (Au) clusters supported on silicon oxide films, graphtized carbon films and magnesium oxide (MgO) films. All the observations have been performed on the clusters consisted of single metal element. Structural stability of ceramics clusters, such as metal-oxide, metal-nitride and metal-carbide clusters, has not been observed by TRHREM although the clusters show anomalous structural and functional properties concerning to solid state physics and materials science.In the present study, the behavior of ceramic, magnesium oxide (MgO) clusters is for the first time observed by TRHREM at 1/60 s time resolution and at atomic resolution down to 0.2 nm.MgO and gold were subsequently deposited on sodium chloride (001) substrates. The specimens, single crystalline MgO films on which Au particles were dispersed were separated in distilled water and observed by using a 200-kV high-resolution electron microscope (JEOL, JEM2010) equipped with a high sensitive TV camera and a video tape recorder system.

Time-resolved high-resolution electron microscopy of grain migration process in MgO films

1996 ◽  
Vol 54 ◽  
pp. 674-675
Author(s):  
T. Kizuka ◽  
M. Iijima ◽  
N. Tanaka
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Boundary Migration ◽  
High Resolution Electron Microscopy ◽  
Video Tape ◽  
Grain Boundary Migration ◽  
Time Resolved ◽  
Resolution Electron

High-resolution electron microscopy (HREM) has been employed intensively to analyze the atomic structures of grain boundaries and interfaces having two dimensional structures inside polycrystalline and composite materials. Furthermore time-resolved HREM (TRHREM) is required to analyze the behavior of grain boundaries and interfaces at atomic scale. The grain boundary migration, which is a typical grain boundary behavior, is a fundamental process relating to structural stability of polycrystalline materials. The mechanism of the migration has been still unknown.In the present study, the variation of atomic arrangement at the grain boundary migration of a MgO [001]Σ5 boundary was analyzed by TRHREM.Magnesium oxide polycrystalline films were prepared by vacuum-deposition on air-cleaved (001) surfaces of sodium chloride at 300°C. TRHREM was carried out at room temperature using a 200-kV electron microscope (JEOL, JEM2010) equipped with a high sensitive TV camera and a video tape recorder. The spatial resolution of the system was 0.2 nm at 200 kV and the time resolution was 1/60 s. Electron beam density was 30 A/cm2.

Time-resolved high-resolution electron microscopy of structural transformation in nanocrystalline ZnO films

1996 ◽  
Vol 54 ◽  
pp. 978-979
Author(s):  
T. Kizuka ◽  
N. Tanaka
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Grain Boundary ◽  
Structural Transformation ◽  
Superplastic Deformation ◽  
Boundary Migration ◽  
High Resolution Electron Microscopy ◽  
Grain Boundary Migration ◽  
Time Resolved ◽  
Resolution Electron

Mechanical properties of polycrystalline materials become anomalous when the grain size and grain boundary length decrease to nanometer scale. For example, ductility and toughness increase significantly in nanometer-grained ceramics (nanocrystalline ceramics). Ductility increases due to appearance of fine-grained-superplastic deformation. Grain boundary migration and interface migration are fundamental processes of the superplastic deformation. Structural transformation of fine grains is a factor which limits the toughness in polycrystalline ceramics because the transformation relaxes internal strain. The behavior of grain boundaries and interfaces, such as diffusion bonding and Czochralski-type crystal growth at ambient temperature, can be analyzed by a time-resolved high-resolution electron microscopy (TRHREM) developed by Kizuka et al.,In the present study, grain boundary migration and successive transformation of crystal structure in nanocrystalline ZnO were investigated by TRHREM.Zinc oxide was vacuum-deposited on air-cleaved (001) surfaces of sodium chloride at 200°C. TRHREM was carried out at room temperature using a 200-kV electron microscope (JEOL, JEM2010) equipped with a high sensitive TV camera and a video tape recorder.

Time-resolved high-resolution electron microscopy of nanometer-scale electron beam processing of PbTe films

1996 ◽  
Vol 54 ◽  
pp. 980-981
Author(s):  
T. Kizuka ◽  
N. Tanaka
Keyword(s):  
Electron Microscopy ◽  
Electron Beam ◽  
Electron Microscope ◽  
High Resolution ◽  
Room Temperature ◽  
High Resolution Electron Microscopy ◽  
Nanometer Scale ◽  
Time Resolved ◽  
Electron Beam Processing ◽  
Resolution Electron

Various kinds of nanometer scale processings are required to produce advanced materials, for example, nano-structured electric devices. Electron beam processing at nanometer scale using STEM and TEM, such as drilling and line-writing, is recently interested as a most useful method. Details of structural change during the processing should be elucidated at atomic resolution in order to establish the processing. In the present work we have processed lead telluride (PbTe) films with nanometer electron beam in a high-resolution transmission electron microscope and in-situ observed the variation of atomic arrangements during the processing.PbTe of 99.99% was vacuum-deposited on air-cleaved (001) surfaces of sodium chloride at room temperature. Time-resolved high-resolution electron microscopy was carried out at room temperature using a 200-kV electron microscope (JEOL, JEM2010) equipped with a high sensitive TV camera and a video tape recorder. The spatial resolution of thesystem was 0.2 nm at 200 kV and the time resolution was 1/60 s. Electron beam irradiation density was 120 A/cm2 at the processing and the observation.

1/60 Sec. Time-Resolved High-Resolution Electron Microscopy of Surface-Diffusion of Tungsten Atoms on MgO (001) Surfaces

1995 ◽  
Vol 404 ◽  
Author(s):  
N. Tanaka ◽  
H. Kimata ◽  
T. Kizuka
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Surface Diffusion ◽  
Diffusion Processes ◽  
Jump Process ◽  
High Resolution Electron Microscopy ◽  
Metal Analysis ◽  
Time Resolved ◽  
Exponential Factor ◽  
Resolution Electron

AbstractSurface diffusion process of tungsten(W)-atoms on MgO (001) surfaces was studied by high-resolution electron microscopy (HREM) in the time resolution of 1/60 s. The W-atoms were prepared on single crystalline MgO (001) films at 300°C by vacuumdeposition of WO3 or W-metal. Analysis of the recorded images revealed individual jump-process of the W-atoms in the substrate temperature from R.T. to 400°C, and gave the barrier potential (Ed) and the pre-exponential factor (D0). The diffusion processes on terraces and along steps were also compared in viewpoint of the jump length.

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