scholarly journals Structural order in ultrathin films of the monolayer protected clusters based upon 4 nm gold nanocrystals: an experimental and theoretical study

2014 ◽  
Vol 16 (34) ◽  
pp. 18098-18104 ◽  
Author(s):  
Nabraj Bhattarai ◽  
Subarna Khanal ◽  
Daniel Bahena ◽  
Jimena A. Olmos-Asar ◽  
Arturo Ponce ◽  
...  
Keyword(s):  
Ultrathin Films ◽  
Theoretical Study ◽  
Size Range ◽  
Gold Nanocrystals ◽  
Metallic Core ◽  
Structural Order ◽  
Monolayer Protected Clusters ◽  
Intermediate Size ◽  
Conventional Methods

The structural order in ultrathin films of monolayer protected clusters (MPCs) is important in a number of application areas but can be difficult to demonstrate by conventional methods, particularly when the metallic core dimension, d, is in the intermediate size-range, 1.5 < d < 5.0 nm.

LOW DIMENSIONAL NON-CRYSTALLOGRAPHIC METALLIC NANOSTRUCTURES: HRTEM SIMULATION, MODELS AND EXPERIMENTAL RESULTS

2006 ◽  
Vol 20 (13) ◽  
pp. 725-751 ◽  
Author(s):  
J. L. RODRÍGUEZ-LÓPEZ ◽  
J. M. MONTEJANO-CARRIZALES ◽  
M. JOSÉ-YACAMÁN
Keyword(s):  
Experimental Evidence ◽  
Bimetallic Nanoparticles ◽  
Size Range ◽  
Simulation Models ◽  
Platonic Solid ◽  
Gold Nanocrystals ◽  
Metallic Particles ◽  
Bimetallic Nanoparticle ◽  
Equilibrium Shapes ◽  
Low Dimensional

Modern nanoparticle research in the field of small metallic systems has confirmed that many nanoparticles take on some Platonic and Archimedean solids related shapes. A Platonic solid looks the same from any vertex, and intuitively they appear as good candidates for atomic equilibrium shapes. A very clear example is the icosahedral ( I h ) particle that only shows {111} faces that contribute to produce a more rounded structure. Indeed, many studies report the I h as the most stable particle at the size range r≤20 Å for noble gases and for some metals. In this review, we report on the structure and shape of mono- and bimetallic nanoparticles in the wide size range from 1–300 nm. First, we present AuPd nanoparticles in the 1–2 nm size range that show dodecahedral atomic growth packing, one of the Platonic solid shapes that have not been identified before in this small size range for metallic particles. Next, with particles in the size range of 2–5 nm, we present an energetic surface reconstruction phenomenon observed also on bimetallic nanoparticle systems of AuPd and AuCu , similar to a re-solidification effect observed during cooling process in lead clusters. These binary alloy nanoparticles show the fivefold edges truncated, resulting in {100} faces on decahedral structures, an effect largely envisioned and reported theoretically, with no experimental evidence in the literature before. Next nanostructure we review is a monometallic system in the size range of ≈5 nm that we termed the decmon. We present here some detailed geometrical analysis and experimental evidence that supports our models. Finally, in the size range of 100–300 nm, we present icosahedrally derived star gold nanocrystals which resembles the great stellated dodechaedron, which is a Kepler–Poisont solid. We conclude then that the shape or morphology of some mono- and bimetallic particles evolves with size following the sequence from atoms to the Platonic solids, and with a slightly greater particle's size, they tend to adopt Archimedean related shapes. If the particle's size is still greater, they tend to adopt shapes beyond the Archimedean (Kepler–Poisont) solids, reaching at the very end the bulk structure of solids. We demonstrate both experimentally and by means of computational simulations for each case that this structural atomic growth sequence is followed in such mono- and bimetallic nanoparticles.

Theoretical Study of the Kerr Effect in Ultrathin Films Fen/Ag(001)

2013 ◽  
Vol 11 (9) ◽  
pp. 1658-1666 ◽  
Author(s):  
M. Boukelkoul ◽  
N. Ouarab ◽  
M. Kharoubi ◽  
A. Haroun
Keyword(s):  
Ultrathin Films ◽  
Kerr Effect ◽  
Theoretical Study

scholarly journals Paternally Transmitted FMR1 Alleles Are Less Stable than Maternally Transmitted Alleles in the Common and Intermediate Size Range

2002 ◽  
Vol 70 (6) ◽  
pp. 1532-1544 ◽  
Author(s):  
Amy K. Sullivan ◽  
Dana C. Crawford ◽  
Elizabeth H. Scott ◽  
Mary L. Leslie ◽  
Stephanie L. Sherman
Keyword(s):  
Size Range ◽  
Intermediate Size ◽  
The Common

Specific surface area and pore structure of allophanic soil clays

Clay Minerals ◽  
1977 ◽  
Vol 12 (1) ◽  
pp. 1-9 ◽  
Author(s):  
E. Paterson
Keyword(s):  
Low Temperature ◽  
Specific Surface ◽  
Pore Structure ◽  
Surface Area ◽  
Specific Surface Area ◽  
Size Range ◽  
Nitrogen Adsorption ◽  
Soil Clays ◽  
Intermediate Size ◽  
Allophanic Soil

AbstractLow temperature nitrogen adsorption has been used to study the external and internal structure of a number of allophanic soil clays. The results indicate that allophane, in addition to having pores in the intermediate size range (2–10 nm radius), contains micropores of < 1 nm radius. The occurrence of hitherto unreported micropores in allophanic clays has necessitated re-evaluation of the validity of specific surface area measurements.

Microtomy of spherical Al2O3 powders

1983 ◽  
Vol 41 ◽  
pp. 74-75
Author(s):  
E.J. Jenkins ◽  
D.S. Tucker ◽  
J.J. Hren
Keyword(s):  
Thin Film ◽  
Size Range ◽  
Particle Aggregation ◽  
Ion Milling ◽  
Thin Sections ◽  
Α Phase ◽  
Convenient Means ◽  
Van Der Waals Attraction ◽  
Negative Feature ◽  
Film Substrate

The size range of mineral and ceramic particles of one to a few microns is awkward to prepare for examination by TEM. Electrons can be transmitted through smaller particles directly and larger particles can be thinned by crushing and dispersion onto a substrate or by embedding in a film followed by ion milling. Attempts at dispersion onto a thin film substrate often result in particle aggregation by van der Waals attraction. In the present work we studied 1-10 μm diameter Al2O3 spheres which were transformed from the amprphous state to the stable α phase.After the appropriate heat treatment, the spherical powders were embedded in as high a density as practicable in a hard EPON, and then microtomed into thin sections. There are several advantages to this method. Obviously, this is a rapid and convenient means to study the microstructure of serial slices. EDS, ELS, and diffraction studies are also considerably more informative. Furthermore, confidence in sampling reliability is considerably enhanced. The major negative feature is some distortion of the microstructure inherent to the microtoming operation; however, this appears to have been surprisingly small. The details of the method and some typical results follow.

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