High resolution electron microscopy of medium-range order in amorphous alloys

1994 ◽  
Vol 179-180 ◽  
pp. 97-101 ◽  
Author(s):  
Yoshihiko Hirotsu
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Amorphous Alloys ◽  
High Resolution Electron Microscopy ◽  
Range Order ◽  
Medium Range Order ◽  
Resolution Electron ◽  
Medium Range

Structure of sputter-deposited amorphous Pd-Si alloy studied by High Resolution Electron Microscopy

1990 ◽  
Vol 48 (4) ◽  
pp. 126-127
Author(s):  
Yoshihiko Hirotsu ◽  
Kazunori Anazawa ◽  
Sigemaro Nagakura
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Amorphous Alloys ◽  
High Resolution Electron Microscopy ◽  
Structural Studies ◽  
X Ray ◽  
Resolution Electron ◽  
Medium Range ◽  
Atomic Distance ◽  
Sputter Deposited

Recent structural studies of amorphous alloys by precise X-ray and neutron diffraction, Mossbauer spectroscopy and NMR have shown an atomic ordering developing beyond the first neighbor atomic distance, which is called a medium range ordering (MRO) of atoms in amorphous alloys. Lattice fringe images extending in a range of 1 to 2 nm have been observed in amorphous alloys by high resolution electron microscopy(HREM), indicating a possible formation of the MRO structures. In our HREM study of amorphous Pd77.5Cu6Si16.5 alloy ribbons, MRO domains with α-Pd-like structure were observed under the most appropriate underfocus condition. For more detailed understanding of MRO structure, it is necessary to calculate HREM images for possible MRO models and compare them with observed ones. In this study, we calculated HREM images for an amorphous Pd80Si20 with (1) a dense random packing(DRP) structure, (2) a FCC MRO structure( a FCC cluster embedded in the DRP structure) and (3) an icosahedral MRO structure( an icosahedral cluster embedded in the DRP structure).

Medium-Range Order in High Al-content Amorphous Alloys Measured by Fluctuation Electron Microscopy

2003 ◽  
Vol 806 ◽  
Author(s):  
W. G. Stratton ◽  
J. Hamann ◽  
J. H. Perepezko ◽  
P. M. Voyles
Keyword(s):  
Electron Microscopy ◽  
Cold Rolling ◽  
Amorphous Alloys ◽  
Melt Spinning ◽  
Amorphous State ◽  
Structural Difference ◽  
Range Order ◽  
Medium Range Order ◽  
Medium Range ◽  
Fluctuation Electron Microscopy

ABSTRACTWe have used fluctuation electron microscopy (FEM) to measure nanoscale mediumrange order in amorphous Al92Sm8. Samples of this amorphous alloy formed by rapid quenching (melt-spinning) show a high density of pure Al nanocrystals (>1020 m-3) after low temperature (< 250 °C) devitrification. In samples amorphized by deformation (cold-rolling), primary Al-crystallization does not occur. This difference in devitrification behavior suggests an underlying structural difference in the amorphous state. FEM is a quantitative microscopy technique for determining nanoscale medium-range order in amorphous materials. Our measurements show that amorphous alloys formed by melt-spinning and cold-rolling have significant structural differences, and that annealing melt-spun alloy under conditions previously shown to modify the devitrification thermodynamics also changes the medium-range structure.

Medium-Range Order in High Al-content Amorphous Alloys Measured by Fluctuation Electron Microscopy

2004 ◽  
Vol 10 (S02) ◽  
pp. 788-789 ◽  
Author(s):  
W. G. Stratton ◽  
P. M. Voyles ◽  
J. Hamann ◽  
J. H. Perepezko
Keyword(s):  
Electron Microscopy ◽  
Amorphous Alloys ◽  
Range Order ◽  
Medium Range Order ◽  
Al Content ◽  
Medium Range ◽  
Fluctuation Electron Microscopy ◽  
High Al Content

Extended abstract of a paper presented at Microscopy and Microanalysis 2004 in Savannah, Georgia, USA, August 1–5, 2004.

Structural analysis of the surface-layer protein of spirillum serpens by high-resolution electron microscopy

1983 ◽  
Vol 41 ◽  
pp. 738-739
Author(s):  
W. H. Wu ◽  
R. M. Glaeser
Keyword(s):  
Electron Microscopy ◽  
Surface Layer ◽  
Structural Analysis ◽  
High Resolution ◽  
Low Dose ◽  
High Resolution Electron Microscopy ◽  
Optical Diffraction ◽  
Surface Layer Protein ◽  
Morphological Unit ◽  
Resolution Electron

Spirillum serpens possesses a surface layer protein which exhibits a regular hexagonal packing of the morphological subunits. A morphological model of the structure of the protein has been proposed at a resolution of about 25 Å, in which the morphological unit might be described as having the appearance of a flared-out, hollow cylinder with six ÅspokesÅ at the flared end. In order to understand the detailed association of the macromolecules, it is necessary to do a high resolution structural analysis. Large, single layered arrays of the surface layer protein have been obtained for this purpose by means of extensive heating in high CaCl2, a procedure derived from that of Buckmire and Murray. Low dose, low temperature electron microscopy has been applied to the large arrays.As a first step, the samples were negatively stained with neutralized phosphotungstic acid, and the specimens were imaged at 40,000 magnification by use of a high resolution cold stage on a JE0L 100B. Low dose images were recorded with exposures of 7-9 electrons/Å2. The micrographs obtained (Fig. 1) were examined by use of optical diffraction (Fig. 2) to tell what areas were especially well ordered.

Electron microscopy of rabbit FC crystals

1983 ◽  
Vol 41 ◽  
pp. 730-731
Author(s):  
Robert A. Grant ◽  
Laura L. Degn ◽  
Wah Chiu ◽  
John Robinson
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
High Resolution Electron Microscopy ◽  
Molecular Replacement ◽  
X Ray ◽  
X Ray Crystallography ◽  
Resolution Electron ◽  
Replacement Technique ◽  
Hydrated Crystal ◽  
Molecular Structure Analysis

Proteolytic digestion of the immunoglobulin IgG with papain cleaves the molecule into an antigen binding fragment, Fab, and a compliment binding fragment, Fc. Structures of intact immunoglobulin, Fab and Fc from various sources have been solved by X-ray crystallography. Rabbit Fc can be crystallized as thin platelets suitable for high resolution electron microscopy. The structure of rabbit Fc can be expected to be similar to the known structure of human Fc, making it an ideal specimen for comparing the X-ray and electron crystallographic techniques and for the application of the molecular replacement technique to electron crystallography. Thin protein crystals embedded in ice diffract to high resolution. A low resolution image of a frozen, hydrated crystal can be expected to have a better contrast than a glucose embedded crystal due to the larger density difference between protein and ice compared to protein and glucose. For these reasons we are using an ice embedding technique to prepare the rabbit Fc crystals for molecular structure analysis by electron microscopy.

High resolution electron microscopy of lanthanum phosphate crystals

1978 ◽  
Vol 36 (1) ◽  
pp. 274-275
Author(s):  
J. C. Wheatley ◽  
J. M. Cowley
Keyword(s):  
Electron Microscopy ◽  
Catalytic Activity ◽  
High Resolution ◽  
Petroleum Industry ◽  
High Resolution Electron Microscopy ◽  
Lanthanum Phosphate ◽  
Good Catalyst ◽  
Resolution Electron ◽  
Good Catalytic Activity ◽  
Physical And Chemical

Rare-earth phosphates are of particular interest because of their catalytic properties associated with the hydrolysis of many aromatic chlorides in the petroleum industry. Lanthanum phosphates (LaPO4) which have been doped with small amounts of copper have shown increased catalytic activity (1). However the physical and chemical characteristics of the samples leading to good catalytic activity are not known.Many catalysts are amorphous and thus do not easily lend themselves to methods of investigation which would include electron microscopy. However, the LaPO4, crystals are quite suitable samples for high resolution techniques.The samples used were obtained from William L. Kehl of Gulf Research and Development Company. The electron microscopy was carried out on a JEOL JEM-100B which had been modified for high resolution microscopy (2). Standard high resolution techniques were employed. Three different sample types were observed: 669A-1-5-7 (poor catalyst), H-L-2 (good catalyst) and 27-011 (good catalyst).

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