Multiply Twinned Structures in Gas-Phase Sintered Stoichiometric FePt Nanoparticles

2001 ◽  
Vol 704 ◽  
Author(s):  
Sonja Stappert ◽  
Bernd Rellinghaus ◽  
Mehmet Acet ◽  
Eberhard F. Wassermann
Keyword(s):  
Gas Phase ◽  
Intermetallic Phase ◽  
Structural Data ◽  
Building Blocks ◽  
High Resolution Electron Microscopy ◽  
Degree Of Crystallinity ◽  
Fept Nanoparticles ◽  
Irregular Shapes ◽  
Resolution Electron ◽  
Partial Formation

AbstractStoichiometric FePt nanoparticles with sizes in the range 3 – 6 nm were prepared in the gas-phase and thermally sintered prior to deposition. Whereas unsintered particles exhibit irregular shapes and a low degree of crystallinity, the majority of the sintered particles are multiply twinned and have predominantly icosahedral structure. There is no indication for the occurance of L10 ordering in the gas-phase sintered particles, although previous post-deposition annealing experiments of unsintered particles had shown the occurrence of partial formation of the L10 FePt intermetallic phase. On the other hand, analysis of the structural data obtained from (high resolution) electron microscopy shows that the relative amount of icosahedral particles increases with increasing sintering temperature. This result is discussed on the basis of a structure model of an irregular icosahedron, which is built up from distorted tetrahedral building blocks. The distortion in each tetrahedron is in accordance with the tetragonally compressed unit cell of the L10-phase.

X-Ray-Optical Multilayer Structures Studied Using High Resolution Electron Microscopy.

1986 ◽  
Vol 77 ◽  
Author(s):  
Mary Beth Stearns ◽  
Amanda K. Petford-Long ◽  
C.-H. Chang ◽  
D. G. Stearns ◽  
N. M. Ceglio ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Substrate Surface ◽  
High Resolution Electron Microscopy ◽  
Atomic Scale ◽  
Degree Of Crystallinity ◽  
Multilayer Systems ◽  
Layer Width ◽  
X Ray ◽  
Resolution Electron

ABSTRACTThe technique of high resolution electron microscopy has been used to examine the structure of several multilayer systems (MLS) on an atomic scale. Mo/Si multilayers, in use in a number of x-ray optical element applications, and Mo/Si multilayers, of interest because of their magnetic properties, have been imaged in cross-section. Layer thicknesses, flatness and smoothness have been analysed: the layer width can vary by up to 0.6nm from the average value, and the layer flatness depends on the quality of the substrate surface for amorphous MLS, and on the details of the crystalline growth for the crystalline materials. The degree of crystallinity and the crystal orientation within the layers have also been investigated. In both cases, the high-Z layers are predominantly crystalline and the Si layers appear amorphous. Amorphous interfacial regions are visible between the Mo and Si layers, and crystalline cobalt suicide interfacial regions between the Co and Si layers. Using the structural measurements obtained from the HREM results, theoretical x-ray reflectivity behaviour has been calculated. It fits the experimental data very well.

Self-Assembled Structures of Gas-Phase Prepared FePt Nanoparticles

2001 ◽  
Vol 707 ◽  
Author(s):  
Bernd Rellinghaus ◽  
Sonja Stappert ◽  
Mehmet Acet ◽  
Eberhard F. Wassermann
Keyword(s):  
Gas Phase ◽  
Elevated Temperatures ◽  
High Mobility ◽  
Carbon Layer ◽  
Carbon Films ◽  
Blocking Temperature ◽  
Fept Nanoparticles ◽  
Irregular Shapes ◽  
Transmission Electron ◽  
Self Assembled

ABSTRACTWe report on a non-lithographic method for the preparation of self-assembled FePt nanoparticles via inert-gas condensation. Prior to deposition the particles can be sintered in flight at temperatures as high as TS = 1273 K. Whereas un-sintered particles have irregular shapes, particles sintered at elevated temperatures TS ≤ 793 K show a regular faceting. (High resolution) transmission electron microscopy ((HR)TEM) shows that these regularly faceted particles are of icosahedral structure. When being deposited onto amorphous carbon films, the gas-phase sintered particles are found to have a high mobility. In particular, for the high-temperature sintered FePt nanoparticles, we observe that this mobility leads to the formation of particle arrays with hexagonal close-packed arrangements. Within these ordered patches, the particles are separated from one another. Analytical investigations using energy filtered TEM (EFTEM) show that a carbon layer is formed between the particles. Magnetization analyses give results showing that the gas-phase sintered particles are superparamagnetic at room temperature with a blocking temperature of TB = 49K.

scholarly journals DNA origami single crystals with Wulff shapes

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Yong Wang ◽  
Lizhi Dai ◽  
Zhiyuan Ding ◽  
Min Ji ◽  
Jiliang Liu ◽  
...  
Keyword(s):  
Single Crystals ◽  
Three Dimensional ◽  
Building Blocks ◽  
High Resolution Electron Microscopy ◽  
Dna Origami ◽  
High Yield ◽  
Binding Modes ◽  
Resolution Electron ◽  
Ultrathin Layer ◽  
Wulff Shapes

AbstractDNA origami technology has proven to be an excellent tool for precisely manipulating molecules and colloidal elements in a three-dimensional manner. However, fabrication of single crystals with well-defined facets from highly programmable, complex DNA origami units is a great challenge. Here, we report the successful fabrication of DNA origami single crystals with Wulff shapes and high yield. By regulating the symmetries and binding modes of the DNA origami building blocks, the crystalline shapes can be designed and well-controlled. The single crystals are then used to induce precise growth of an ultrathin layer of silica on the edges, resulting in mechanically reinforced silica-DNA hybrid structures that preserve the details of the single crystals without distortion. The silica-infused microcrystals can be directly observed in the dry state, which allows meticulous analysis of the crystal facets and tomographic 3D reconstruction of the single crystals by high-resolution electron microscopy.

Self-Assembled Structures of Gas-Phase Prepared FePt Nanoparticles

2001 ◽  
Vol 705 ◽  
Author(s):  
Bernd Rellinghaus ◽  
Sonja Stappert ◽  
Mehmet Acet ◽  
Eberhard F. Wassermann
Keyword(s):  
Gas Phase ◽  
Elevated Temperatures ◽  
High Mobility ◽  
Carbon Layer ◽  
Carbon Films ◽  
Blocking Temperature ◽  
Fept Nanoparticles ◽  
Irregular Shapes ◽  
Transmission Electron ◽  
Self Assembled

AbstractWe report on a non-lithographic method for the preparation of self-assembled FePt nanoparticles via inert-gas condensation. Prior to deposition the particles can be sintered in flight at temperatures as high as TS = 1273 K. Whereas un-sintered particles have irregular shapes, particles sintered at elevated temperatures TS ≥ 793 K show a regular faceting. (High resolution) transmission electron microscopy ((HR)TEM) shows that these regularly faceted particles are of icosahedral structure. When being deposited onto amorphous carbon films, the gas-phase sintered particles are found to have a high mobility. In particular, for the high-temperature sintered FePt nanoparticles, we observe that this mobility leads to the formation of particle arrays with hexagonal close-packed arrangements. Within these ordered patches, the particles are separated from one another. Analytical investigations using energy filtered TEM (EFTEM) show that a carbon layer is formed between the particles. Magnetization analyses give results showing that the gas-phase sintered particles are superparamagnetic at room temperature with a blocking temperature of TB = 49K.

High Resolution TEM and EDX Investigation of Metal Coated Nanoparticles

2001 ◽  
Vol 7 (S2) ◽  
pp. 388-389
Author(s):  
Jun Jiao ◽  
Fangqiong Tang
Keyword(s):  
High Resolution ◽  
Colloidal Stability ◽  
Metal Oxide Nanoparticles ◽  
Sol Gel ◽  
Building Blocks ◽  
High Resolution Electron Microscopy ◽  
Coated Nanoparticles ◽  
Resolution Electron ◽  
High Resolution Tem ◽  
Potential Applications

Nanoparticles are increasingly being heralded as the next-generation building blocks for modern materials design. Coating of semiconductor, metal, or metal oxide nanoparticles with a thin layer of a compatible material makes possible the control of interparticle and particle-matrix interactions, thereby further improving functional properties of devices and expanding the range of potential applications . The core-shell geometry has previously allowed for the enhancement of luminescence of semiconductor nanoparticles, charging of metal cores, chemical and colloidal stability, and optimization of magnetic properties of nanoparticles.The work reported here uses new approaches to synthesize metal-coated nanoparticles characterized with high-resolution electron microscopy (HRTEM), micro-diffraction, and electron energy dispersive X-ray (EDX). Colloidal uniform composite nanoparticles of SiO2/TiO2 were synthesized using the sol-gel process. Fig. l-(a) shows a TEM micrograph of a group of particles coated with an outer layer.

Amorphization of Al10(Vx,Cr1-x) intermetallic phase

1994 ◽  
Vol 52 ◽  
pp. 662-663
Author(s):  
V. Radmilovic ◽  
R. Kilaas ◽  
G. Thomas
Keyword(s):  
Electron Microscopy ◽  
Electron Beam ◽  
Chemical Composition ◽  
Intermetallic Phase ◽  
High Resolution Electron Microscopy ◽  
Intermetallic Phases ◽  
Compositional Variation ◽  
Aerospace Applications ◽  
Resolution Electron ◽  
The Stability

The stability of phases in alloy systems, including stability in irradiation environments, is conditio sine qua non of their engineering applications. Thus, investigations of different phenomena, such as compositional variation, segregation, order/disorder transitions and amorphization in different phases under irradiation, is of great importance.In the present paper experiments are reported on using high resolution electron microscopy and electron diffraction to observe the stability of Al-V-Cr based intermetallic phase in Al based alloys which are considered potential material for aerospace applications. In addition, it is an attempt to establish a possible method for investigation of disordering and amorphization in intermetallic phases under the electron beam, as first observed by Thomas et al. in the Ni-Ti system.The Al based alloy with chemical composition (in wt.%) Al - 2.3 Li - 1.0 Cu - 0.8 Mg - 1.0 Cr - 1.0 V - 0.5 Zr was solutionized at 530°C for 4 hours, water quenched, and aged for 48 hours at 148°C.

Recent Applications of High Resolution Electron Microscopy to Crystalline Arrays of Virus Particles

1978 ◽  
Vol 36 (3) ◽  
pp. 470-482 ◽  
Author(s):  
R.W. Horne
Keyword(s):  
Electron Microscopy ◽  
Image Processing ◽  
Analytical Techniques ◽  
Staining Technique ◽  
High Resolution Electron Microscopy ◽  
Optical Diffraction ◽  
Full Potential ◽  
Virus Particles ◽  
Resolution Electron ◽  
Wide Range

The technique of surrounding virus particles with a neutralised electron dense stain was described at the Fourth International Congress on Electron Microscopy, Berlin 1958 (see Home & Brenner, 1960, p. 625). For many years the negative staining technique in one form or another, has been applied to a wide range of biological materials. However, the full potential of the method has only recently been explored following the development and applications of optical diffraction and computer image analytical techniques to electron micrographs (cf. De Hosier & Klug, 1968; Markham 1968; Crowther et al., 1970; Home & Markham, 1973; Klug & Berger, 1974; Crowther & Klug, 1975). These image processing procedures have allowed a more precise and quantitative approach to be made concerning the interpretation, measurement and reconstruction of repeating features in certain biological systems.

One Million Direct Magnification Microscopy

1971 ◽  
Vol 29 ◽  
pp. 166-167
Author(s):  
J. A. Hugo ◽  
V. A. Phillips
Keyword(s):  
Electron Microscopy ◽  
High Resolution Electron Microscopy ◽  
Illumination Level ◽  
Level Of Detail ◽  
Photographic Emulsion ◽  
Low Contrast ◽  
Fluorescent Screen ◽  
Resolution Electron ◽  
Lattice Images ◽  
Electron Microscopes

A continuing problem in high resolution electron microscopy is that the level of detail visible to the microscopist while he is taking a picture is inferior to that obtainable by the microscope, readily readable on a photographic emulsion and visible in an enlargement made from the plate. Line resolutions, of 2Å or better are now achievable with top of the line 100kv microscopes. Taking the resolution of the human eye as 0.2mm, this indicates a need for a direct viewing magnification of at least one million. However, 0.2mm refers to optimum viewing conditions in daylight or the equivalent, and certainly does not apply to a (colored) image of low contrast and illumination level viewed on a fluorescent screen through a glass window by the dark-adapted eye. Experience indicates that an additional factor of 5 to 10 magnification is needed in order to view lattice images with line spacings of 2 to 4Å. Fortunately this is provided by the normal viewing telescope supplied with most electron microscopes.

Lattice Imaging of Twin, Lath and α/Martensite Boundaries in Duplex Low Carbon Steels

1977 ◽  
Vol 35 ◽  
pp. 118-119
Author(s):  
J. Y. Koo ◽  
G. Thomas
Keyword(s):  
High Resolution Electron Microscopy ◽  
Ferrite Matrix ◽  
Carbon Steels ◽  
Bright Field Image ◽  
Low Carbon ◽  
Lattice Imaging ◽  
Bright Field ◽  
Lattice Image ◽  
New Information ◽  
Resolution Electron

High resolution electron microscopy has been shown to give new information on defects(1) and phase transformations in solids (2,3). In a continuing program of lattice fringe imaging of alloys, we have applied this technique to the martensitic transformation in steels in order to characterize the atomic environments near twin, lath and αmartensite boundaries. This paper describes current progress in this program.Figures A and B show lattice image and conventional bright field image of the same area of a duplex Fe/2Si/0.1C steel described elsewhere(4). The microstructure consists of internally twinned martensite (M) embedded in a ferrite matrix (F). Use of the 2-beam tilted illumination technique incorporating a twin reflection produced {110} fringes across the microtwins.

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.

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