Characterization of Pd/V Multilayer Structures by High-Angle Annular Dark-Field Microscopy and High Resolution Tem

1991 ◽  
Vol 238 ◽  
Author(s):  
J. Liu ◽  
Y. Cheng ◽  
G. D. Lewen ◽  
M. B. Stearns
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
High Resolution Electron Microscopy ◽  
Dark Field ◽  
Compositional Variation ◽  
High Angle ◽  
Dark Field Microscopy ◽  
Annular Dark Field ◽  
Chemical Modulation ◽  
Substrate Temperatures

ABSTRACTThe structures of e-beam evaporated Pd/V multilayer thin films, which were fabricated at different substrate temperatures, have been characterized by high-angle annular dark-field microscopy and high resolution electron microscopy techniques. X-ray scattering and crosssectional electron microscopy showed that both the Pd and V layers are composed of small textured crystallites with dominant orientations of Pd (111) and V (110). It is found that Pd/V multilayers with high chemical modulation can be fabricated at substrate temperatures around 350 K and at a deposition rate of 0.2 nm/s. Here high-angle annular dark-field microscopy has been shown to provide direct information about the compositional variation of the interlayers of these ML.

Characterization of Ultrathin Doping Layers in Semiconductors

1997 ◽  
Vol 3 (4) ◽  
pp. 352-363 ◽  
Author(s):  
C.P. Liu ◽  
R.E. Dunin-Borkowski ◽  
C.B. Boothroyd ◽  
P.D. Brown ◽  
C.J. Humphreys
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
High Resolution Electron Microscopy ◽  
Dark Field ◽  
High Angle ◽  
Compositional Profile ◽  
Resolution Electron ◽  
Annular Dark Field ◽  
Contrast Analysis

Abstract: The compositional profile of a narrow layer of InAsxPl−x in InP has been determined using energy-filtered Fresnel contrast analysis, high-resolution electron microscopy (HREM), and high-angle annular dark-field (HAADF) imaging. The consistency of the results obtained using the three techniques is discussed, and conclusions are drawn both about the validity of interpreting the magnitude of Fresnel contrast data quantitatively and about the degree to which high-angle annular dark-field images of such materials are affected by inelastic scattering and strain.

High Resolution TEM Studies On Palladium, Rhodium Nanoparticles

2001 ◽  
Vol 7 (S2) ◽  
pp. 1100-1101
Author(s):  
M. José-Yacamán ◽  
M. Marín-Almazo ◽  
J.A. Ascencio
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Indirect Evidence ◽  
High Resolution Electron Microscopy ◽  
Dark Field ◽  
Rhodium Nanoparticles ◽  
Resolution Electron ◽  
Annular Dark Field ◽  
High Resolution Tem ◽  
Important Field

The field of catalysis is one of the most important areas of the nano-sciences for many years. in deed the goal of having a catalyst, with the maximum active area exposed to a chemical reaction, has produced enormous amount of research in nanoparticles. Particularly, the metal nanoparticles study is a very important field in catalysis. Electron Microscopy is one of the techniques that have played a mayor role on studding nanoparticles. Since bright field images, dark field techniques, to the high-resolution atomic images of nanoparticles and more recently the High Angle Annular dark field images or Z-contrast. However this technique provides only indirect evidence of the atomic arrangements on the particles. High Resolution Electron Microscopy (HREM) still appears as a very powerful technique to study nanoparticles and their internal structure. Among the most interesting metals to study is the palladium, which acts for instance as excellent catalyst for hydrogenation of unsaturated hydrocarbons and has many other applications such as environmental catalysts.

scholarly journals De los micrómetros a los picómetros: evolución de las técnicas de microscopia para el estudio de nanomateriales

2019 ◽  
Vol 12 (23) ◽  
pp. 1
Author(s):  
Margarita Rivera Hernandez ◽  
Jesús Arenas-Alatorre
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Resolution ◽  
Scanning Transmission Electron Microscopy ◽  
Dark Field ◽  
High Angle ◽  
Scanning Transmission Electron ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Annular Dark Field

Sin lugar a duda, las técnicas de microscopía electrónica (ME) y microscopia de sonda de barrido (SPM) han contribuido enormemente al estudio de nanomateriales, dando información de propiedades morfológicas, estructurales, de superficie, eléctricas y magnéticas, entre muchas otras. Las técnicas más empleadas para estudios a nanoescala han sido las microscopías electrónicas de transmisión y barrido, y por otro lado, las de efecto túnel y de fuerza atómica, respectivamente. Los avances tecnológicos en los últimos años de estas técnicas han permitido límites de resolución que hace 25 años era inimaginables, siendo los últimos valores alcanzados de decenas de picómetros (10<sup>-12</sup> m). Cabe señalar, que más allá de esto, las técnicas de microscopia mencionadas han crecido en sus capacidades de análisis en el campo de las nanociencias y nanotecnología, dando lugar a otras técnicas como microscopía electrónica de barrido por transmisión (STEM, del inglés Scanning Transmission Electron Microscopy), Imagen en campo obscuro a ángulo grande en alta resolución (HR-HAADF, del inglés High Resolution - High Angle Annular Dark Field), Crio-Microscopía Electrónica, Tomografía electrónica, Espectroscopía de tunelamiento, Tunelamiento inelástico, Curvas de fuerza, etc. Lo anterior, no solo ha complementado la información morfológica y estructural, sino que también, ha contribuido al entendimiento de fenómenos de interacción y propiedades fisicoquímicas a escalas atómicas y moleculares. En este artículo se hace un análisis de la trascendencia actual que tienen las técnicas de microscopía electrónica, así como las de microscopia de sonda de barrido (SPM), y se menciona brevemente el alcance de estas técnicas como métodos de modificación de superficies a ultra alta resolución, como el caso de la nanolitografía y nanomanipulación, que estan abriendo un panorama enorme en el desarrollo de las  tecnologías del futuro.

scholarly journals Evidence of a minority monoclinic LaNiO2.5 phase in lanthanum nickelate thin films

2017 ◽  
Vol 19 (13) ◽  
pp. 9137-9142 ◽  
Author(s):  
L. López-Conesa ◽  
J. M. Rebled ◽  
D. Pesquera ◽  
N. Dix ◽  
F. Sánchez ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Thin Films ◽  
Transmission Electron Microscopy ◽  
High Resolution ◽  
Dark Field ◽  
High Angle ◽  
Transmission Electron ◽  
Lanthanum Nickelate ◽  
Annular Dark Field

LaNiO3 (LNO) thin films of 14 nm and 35 nm thicknesses grown epitaxially on LaAlO3 (LAO) and (LaAlO3)0.3(Sr2TaAlO6)0.7 (LSAT) substrates are studied using High Resolution Transmission Electron Microscopy (HRTEM) and High Angle Annular Dark Field (HAADF) imaging.

The Effect of Substrates / Ligands on Metal Nanocatalysts Investigated By Quantitative Z-Contrast Imaging and High Resolution Electron Microscopy

2005 ◽  
Vol 876 ◽  
Author(s):  
Huiping Xu ◽  
Laurent Menard ◽  
Anatoly Frenkel ◽  
Ralph Nuzzo ◽  
Duane Johnson ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Three Dimensional ◽  
High Resolution Electron Microscopy ◽  
Dark Field ◽  
Contrast Imaging ◽  
Mixed Ligands ◽  
Resolution Electron ◽  
Annular Dark Field ◽  
Z Contrast

AbstractOur direct density function-based simulations of Ru-, Pt- and mixed Ru-Pt clusters on carbon-based supports reveal that substrates can mediate the PtRu5 particles [1]. Oblate structure of PtRu5 on C has been found [2]. Nevertheless, the cluster-substrate interface interactions are still unknown. In this work, we present the applications of combinations of quantitative z-contrast imaging and high resolution electron microscopy in investigating the effect of different substrates and ligand shells on metal particles. Specifically, we developed a relatively new and powerful method to determine numbers of atoms in a nanoparticle as well as three-dimensional structures of particles including size and shape of particles on the substrates by very high angle (~96mrad) annular dark-field (HAADF) imaging [2-4] techniques. Recently, we successfully synthesize icosahedra Au13 clusters with mixed ligands and cuboctahedral Au13 cores with thiol ligands, which have been shown by TEM to be of sub-nanometer size (0.84nm) and highly monodisperse narrow distribution. X-ray absorption and UV-visible spectra indicate many differences between icosahedra and cuboctahedral Au13 cores. Particles with different ligands show different emissions and higher quantum efficiency has been found in Au11 (PPH3) SC12)2C12. We plan to deposit those ligands-protected gold clusters onto different substrates, such as, TiO2 and graphite, etc. Aforementioned analysis procedure will be performed for those particles on the substrates and results will be correlated with that of our simulations and activity properties. This approach will lead to an understanding of the cluster-substrates relationship for consideration in real applications.

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