AFM observations of the surface morphology of metallic glasses Fe78B13Si9 in the early stage of crystallization

1992 ◽  
Vol 7 (8) ◽  
pp. 2126-2130 ◽  
Author(s):  
Yoshihisa Watanabe ◽  
Yoshikazu Nakamura
Keyword(s):  
Surface Morphology ◽  
Metallic Glasses ◽  
Crystallization Process ◽  
Early Stage ◽  
Spatial Density ◽  
Exoelectron Emission ◽  
Force Microscopy ◽  
Atomic Force ◽  
Transmission Electron ◽  
Surface Image

The change in the surface morphology of metallic glasses Fe78B13Si9 during the early stage of the crystallization process has been studied mainly by atomic force microscopy (AFM). Specimens of 50-μm thickness have been heated up to 323 K, 373 K, 423 K, and 523 K with a heating rate of 30 K/min in vacuum, and then the surface morphology of each specimen has been observed by AFM in air. In the surface image of the specimen heated to 323 K, many holes are observed and inside the holes single or plural protrusions can be observed. Clusters composed of aggregated protrusions are also found like islands in the amorphous sea. The specimen heated to 323 K has also been observed by a high-resolution transmission electron microscope and crystalline structures among the amorphous matrix have been detected. From the selected area diffraction study, the crystalline structure is found to be α–Fe crystallites. In contrast, in the AFM image of the surface of the specimen heated to 423 K, no holes are seen and many protrusions are found to extend above the surface and form several parallel lines. The spatial density of protrusions above the surface becomes much higher in the specimen heated to 523 K. We propose that this change in the surface morphology during heat treatments indicates the process of nucleation and growth of α–Fe crystallites in the surface of metallic glasses. It is also found that the stage of many protrusions extending above the surface corresponds with the beginning of exoelectron emission from the surface. This result suggests that exoelectron emission and surface crystallization connect with each other.

Exoelectron emission from unexcited metallic glasses Fe40Ni38Mo4B18 during heat treatment

1993 ◽  
Vol 8 (5) ◽  
pp. 1041-1044
Author(s):  
Yoshihisa Watanabe ◽  
Yoshikazu Nakamura ◽  
Tadayoshi Kubozoe
Keyword(s):  
Heat Treatment ◽  
Metallic Glasses ◽  
Background Level ◽  
Spatial Density ◽  
Exoelectron Emission ◽  
Force Microscopy ◽  
Atomic Force ◽  
Lower Temperature ◽  
Constant Heating ◽  
Ionizing Radiations

In order to elucidate a mechanism for exoelectron emission from metallic glasses during heat treatment, metallic glasses Fe40Ni38Mo4B18, which have a 140 K lower crystallization temperature than the metallic glasses Fe78B13Si9 reported previously, were heated up to 723 K with a constant heating rate of 0.5 K/s under ultrahigh vacuum condition. Although specimens were not excited by ionizing radiations, mechanical treatment, or chemical processes prior to measurements, exoelectrons have been detected for the first heating cycle. However, in the subsequent heating cycles, the counting rate does not exceed the background level. These results agree well with our previous report about metallic glasses Fe78B13Si9, but it is recently found that from the present glasses exoelectrons are emitted from the lower temperature region, and the total number of emitted exoelectrons is larger than that from the previous glasses. An atomic force microscopy (AFM) study reveals many crystallites formed on the surface of the heated specimen, and the spatial density of crystallites on the surface is much higher than that of previous glasses. Both results of exoelectron measurements and AFM observations show that the number of emitted exoelectrons increases with increasing the number of crystallites on the surface. This result implies that exoelectrons are emitted associated with the crystallites formation process on the surface.

Influence of MeV Gamma Photons on Thermally Stimulated Exoelectron Emission from MgO Films

2021 ◽  
Vol 903 ◽  
pp. 162-167
Author(s):  
Marina Romanova ◽  
Regīna Burve ◽  
Yuri Dekhtyar ◽  
Kristaps Palskis ◽  
Vera Serga
Keyword(s):  
Atomic Force Microscopy ◽  
Radiation Dose ◽  
Surface Morphology ◽  
Percentage Increase ◽  
Exoelectron Emission ◽  
X Ray Diffraction ◽  
X Ray ◽  
Force Microscopy ◽  
Atomic Force ◽  
Gamma Irradiated

The effect of 6 MeV gamma photons on thermally stimulated exoelectron emission (TSEE) spectra of MgO films was studied. The films were fabricated on Si/SiO2 substrates using the extraction-pyrolytic method. The crystalline structure and surface morphology of the films were characterized by X-ray diffraction (XRD) and atomic force microscopy (AFM). TSEE spectra of MgO films had emission peaks at about 450 oC and 525 oC. The area under the TSEE peaks increased after repeated TSEE measurements. In the case of gamma-irradiated films, the percentage increase in the area depended on the radiation dose, decreasing linearly with an increase in the radiation dose from 0 to 80 Gy. The results suggest that gamma radiation reduced the density of trapped electrons present in the as-grown MgO films or created competing hole traps that inhibited TSEE from the films.

Surface Morphology of SiGe Epitaxial Layers Grown on Uniquely Oriented Si Substrates

2000 ◽  
Vol 648 ◽  
Author(s):  
Morgan E. Ware ◽  
Robert J. Nemanich
Keyword(s):  
Surface Morphology ◽  
Lattice Mismatch ◽  
Morphological Structure ◽  
Epitaxial Layers ◽  
Misfit Dislocations ◽  
Force Microscopy ◽  
Si Substrates ◽  
Atomic Force ◽  
Transmission Electron ◽  
Relationship Of

AbstractThe 4% lattice mismatch between Si and Ge creates strain in epitaxial layers of SiGe alloys on Si, and this strain can manifest itself in the morphological structure of the surface of the epitaxial layer. This study explores the relationship of the evolution of the surface morphology of SiGe layers grown on a range of Si surface orientations. We have grown thin, strained and thick, relaxed layers of Si0.7Ge0.3 by solid source molecular beam epitaxy on substrates with surface normals rotated from [001] towards [111] by angles of θ = (0, 2, 4, 10, 22) degrees. The surface morphology was investigated by atomic force microscopy, which showed considerable ordering of surface features on relaxed samples. These features evolve from hut-like structures at 0 degrees to large mesa-like structures separated by pits and crevices at 22 degrees. The organization of these features is also shown to vary with the substrate orientation. Each surface has characteristic directions along which features are aligned, and these directions vary continuously with the angle of rotation of the substrate. Transmission electron microscopy confirmed that misfit dislocations had formed along those same directions. The state of relaxation of each layer is quantified by Raman spectroscopy in order to make a direct correlation between residual strain and surface morphology.

Surface Roughening and Composition Modulation of ZnSe-related II-VI epitaxial films

1996 ◽  
Vol 448 ◽  
Author(s):  
Shigetaka Tomiya ◽  
Hironori Tsukamoto ◽  
Satoshi Itoh ◽  
Kazushi Nakano ◽  
Etsuo Morita ◽  
...  
Keyword(s):  
Surface Morphology ◽  
Surface Reconstruction ◽  
Epitaxial Films ◽  
Surface Roughening ◽  
Force Microscopy ◽  
Composition Modulation ◽  
Atomic Force ◽  
Transmission Electron ◽  
Rich Condition ◽  
Lattice Matched

AbstractWe have investigated ZnSSe and ZnMgSSe epitaxial layers lattice-matched to GaAs (001) substrates grown by molecular beam epitaxy using atomic force microscopy and transmission electron microscopy. Under II-rich conditions with c(2x2) surface reconstruction, surface morphology exhibited corrugation aligned in the [1ī0] direction and composition modulation was observed in the same [1ī0] direction. Under VI-rich condition with (2x1) surface reconstruction, the surface morphology becomes rounded grain-like and composition modulation was not observed. The formation of composition modulation is associated with the surface corrugated structures.

A TEM study of the microstructures formed during the crystallization of Ni–Zr metallic glasses

1991 ◽  
Vol 6 (4) ◽  
pp. 755-759 ◽  
Author(s):  
R. Allem ◽  
G. L'Espérance ◽  
Z. Altounian ◽  
J.O. Ström-Olsen
Keyword(s):  
Metallic Glasses ◽  
Crystallization Process ◽  
Early Stage ◽  
Face Centered Cubic ◽  
Simple Cubic ◽  
Transmission Electron ◽  
The Face ◽  
Face Centered ◽  
Two Phases ◽  
Average Size

The microstructure of two metastable crystalline phases, which are formed during the first step of the crystallization process in Ni–Zr metallic glasses, was investigated by transmission electron microscopy. For the composition Ni33Zr67, crystallites with average size of 150 nm having the face-centered cubic E93 structure are formed. For the Ni42Zr58 composition, 100 nm size crystallites with a simple cubic unit cell, space group Pa3 are formed. The microstructure of the crystallites in the early stage of crystallization of the two phases is similar to globular morphology and internal striations.

Distribution of sulphated polysaccharides within calcareous biominerals suggests a widely shared two-step crystallization process for the microstructural growth units

2008 ◽  
Vol 72 (1) ◽  
pp. 233-237 ◽  
Author(s):  
J. P. Cuif ◽  
Y. Dauphin ◽  
B. Farre ◽  
G. Nehrke ◽  
J. Nouet ◽  
...  
Keyword(s):  
Crystallization Process ◽  
Growth Layer ◽  
Microscopy Imaging ◽  
Sulphated Polysaccharides ◽  
Force Microscopy ◽  
Atomic Force ◽  
Transmission Electron ◽  
Vital Effects ◽  
Ca Carbonate

AbstractSynchrotron-based XANES characterization of sulphated sulphur combined with atomic force microscopy and transmission electron microscopy (imaging and diffraction) allow insights into the crystallization of the calcareous units produced by invertebrates. As a result of a series of converging data, reticulate crystallization of the amorphous Ca-carbonate molecules conveyed to the micron-thick growth layer by the sumicrometric organo-mineral units seems a reasonable hypothesis, providing us with a method of explaining the multiple and taxonomy-linked ‘vital effects’ which have long been recognized among the calcareous biocrystals.

Correlation between Extended Defects and Surface Morphology in MBE Grown InAs/GaAs Heterostructures

1995 ◽  
Vol 399 ◽  
Author(s):  
M.R. Bruni ◽  
G. Padeletti ◽  
M.G. Simeone ◽  
L. Francesio ◽  
P. Franzosi ◽  
...  
Keyword(s):  
Surface Morphology ◽  
Growth Temperature ◽  
Crystal Defects ◽  
Extended Defects ◽  
X Ray Diffraction ◽  
X Ray ◽  
Force Microscopy ◽  
Atomic Force ◽  
Gaas Substrates ◽  
Transmission Electron

ABSTRACTInAs single layers were grown by Molecular Beam Epitaxy on nominally (001) oriented GaAs substrates at growth temperatures ranging from 350 °C to 500 °C and thicknesses between 1 nm and 6 μm. A systematic study of the influence of growth temperature and thickness on crystal defects and surface morphology is discussed by comparing High Resolution X-Ray Diffraction, Transmission Electron Microscopy and Atomic Force Microscopy investigations.Surface hexagonal shaped holes were observed to develop at the lowest temperatures starting from an heterolayer thickness of 50 nm. Both misfit and threading dislocations were revealed; moreover the correlation between hexagonal shaped surface holes and mixed dislocations, with the component of the Burgers vector (b) along the growth axis larger than the minimum interatomic distance, is discussed. The holes increase in size and decrease in density by increasing the layer thickness. An almost complete surface planarization is observed at a thickness of 6 μm by increasing the growth temperature up to 500 °C.

Scanning tunneling microscopy and atomic force microscopy: New tools for biology

1989 ◽  
Vol 47 ◽  
pp. 778-779
Author(s):  
CE Bracker ◽  
P. K. Hansma
Keyword(s):  
Physical Property ◽  
Scanning Probe ◽  
Scanning Tunneling ◽  
Small Scale ◽  
Tunneling Microscopy ◽  
Force Microscopy ◽  
New Family ◽  
Small Probe ◽  
Atomic Force ◽  
Transmission Electron

A new family of scanning probe microscopes has emerged that is opening new horizons for investigating the fine structure of matter. The earliest and best known of these instruments is the scanning tunneling microscope (STM). First published in 1982, the STM earned the 1986 Nobel Prize in Physics for two of its inventors, G. Binnig and H. Rohrer. They shared the prize with E. Ruska for his work that had led to the development of the transmission electron microscope half a century earlier. It seems appropriate that the award embodied this particular blend of the old and the new because it demonstrated to the world a long overdue respect for the enormous contributions electron microscopy has made to the understanding of matter, and at the same time it signalled the dawn of a new age in microscopy. What we are seeing is a revolution in microscopy and a redefinition of the concept of a microscope.Several kinds of scanning probe microscopes now exist, and the number is increasing. What they share in common is a small probe that is scanned over the surface of a specimen and measures a physical property on a very small scale, at or near the surface. Scanning probes can measure temperature, magnetic fields, tunneling currents, voltage, force, and ion currents, among others.

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