Microdiffraction Studies of Small Gold Metallic Particles

1983 ◽  
Vol 31 ◽  
Author(s):  
Miguel Jose-Yacaman ◽  
Alfredo Gomez ◽  
Krystyna Truszkowska
Keyword(s):  
Diffraction Pattern ◽  
Crystalline Structure ◽  
Size Range ◽  
Hexagonal Lattice ◽  
Anomalous Diffraction ◽  
Single Crystalline ◽  
Gold Particles ◽  
Metallic Particles ◽  
Splitting Effect

ABSTRACTThe crystalline structure of small gold particles in the size range between 50–200 Å is studied using STEM in microdiffraction.It is found that some single-crystalline particles showed an anomalous diffraction pattern. In some cases these pattern be indexed as an hexagonal lattice with a ratio c/a= 2.46. A number of models to explain the hexagonal diffraction are discussed. In some other cases the patterns correspond to fcc structures but with a large splitting effect. The results reveal the strong dynamical character of the diffraction by small gold particles.

Microdiffraction Patterns of Small Metallic Particles II; Theoretical Analysis

1982 ◽  
Vol 40 ◽  
pp. 668-669
Author(s):  
A. Gómez ◽  
P. Schabes-Retchkiman ◽  
M. José-Yacamán ◽  
T. Ocaña
Keyword(s):  
Experimental Data ◽  
Electron Diffraction ◽  
Theoretical Analysis ◽  
Size Range ◽  
Dynamical Theory ◽  
Metallic Particles ◽  
Splitting Effect

The splitting effect that is observed in microdiffraction pat-terns of small metallic particles in the size range 50-500 Å can be understood using the dynamical theory of electron diffraction for the case of a crystal containing a finite wedge. For the experimental data we refer to part I of this work in these proceedings.

Crystal structure-size relationship in ultrafine metallic particles

1989 ◽  
Vol 47 ◽  
pp. 266-267
Author(s):  
Jun Liu ◽  
Mehmet Sarikaya ◽  
Ilhan A. Aksay
Keyword(s):  
Ultrafine Particles ◽  
Carbon Film ◽  
Lattice Defects ◽  
Careful Examination ◽  
Seeded Growth ◽  
Gold Particles ◽  
Metallic Particles ◽  
Interfacial Structures ◽  
Typical Particle ◽  
Many Particles

Ultrafine particles usually have unique physical properties. This study illustrates how the lattice defects and interfacial structures between particles are related to the size of ultrafine crystalline gold particles.Colloidal gold particles were produced by reducing gold chloride with sodium citrate at 100°C. In this process, particle size can be controlled by changing the concentration of the reactant. TEM samples are prepared by transferring a small amount of solution onto a thin (5 nm) carbon film which is suspended on a copper grid. In this work, all experiments were performed with Philips 430T at 300 kV.With controlled seeded growth, particles of different sizes are produced, as shown in Figure 1. By a careful examination, it can be resolved that very small particles have lattice defects with complex interfaces. Some typical particle structures include multiple twins, resulting in a five-fold symmetry bicrystals, and highly disordered regions. Many particles are too complex to be described by simple models.

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.

Surface structure effects of small particles

1984 ◽  
Vol 42 ◽  
pp. 658-659
Author(s):  
V. Castaño ◽  
A. Gömez ◽  
M. José-Yacamán
Keyword(s):  
Crystal Structure ◽  
Diffraction Pattern ◽  
Gold Particle ◽  
Noble Metals ◽  
Theoretical Calculations ◽  
Dynamical Theory ◽  
Small Particles ◽  
Gold Particles ◽  
The Past ◽  
Diffraction Patterns

Small particles of noble metals have been widely used in catalysis. In the past, very little has been known about crystal structure of this kind of particles. However, STEM microdiffraction patterns can now provide a great deal of information concerning the morphological characteristcs of these particles. In this comunication we report microdiffraction studies of small gold particles (∼ 100 Å) grown by evaporation onto KCl substracte. This investigation was carried out by comparing theoretical diffraction patterns from wedgeshaped crystals (with and without surface vacancies) with experimental microdiffraction patterns. The theoretical calculations have been based on the multislice formulation of Dynamical Theory.Fig. 1 shows a diffraction pattern of a gold particle. In addition of the (111) FCC zone, six forbidden reflections are clearly seen. These reflections have been observed in the past in films of gold and large gold particles.

Stereo-epitaxial growth of single-crystal Ni nanowires and nanoplates from aligned seed crystals

Nanoscale ◽  
2016 ◽  
Vol 8 (19) ◽  
pp. 10291-10297 ◽  
Author(s):  
Hyoban Lee ◽  
Youngdong Yoo ◽  
Taejoon Kang ◽  
Jiyoung Lee ◽  
Eungwang Kim ◽  
...  
Keyword(s):  
Single Crystal ◽  
Epitaxial Growth ◽  
Crystalline Structure ◽  
Vapor Phase ◽  
Growth Direction ◽  
Single Crystalline ◽  
Seed Crystals ◽  
Sapphire Substrates

Vertical Ni NWs, inclined Ni NWs, and vertical Ni nanoplates were epitaxially grown on sapphire substrates with a single-crystalline structure in the vapor phase. The morphology and growth direction of Ni nanostructures are determined by Ni seed crystals.

Scalable synthesis of high-quality transition metal dichalcogenide nanosheets and their application as sodium-ion battery anodes

2016 ◽  
Vol 4 (44) ◽  
pp. 17370-17380 ◽  
Author(s):  
Jingwen Zhou ◽  
Jian Qin ◽  
Lichao Guo ◽  
Naiqin Zhao ◽  
Chunsheng Shi ◽  
...  
Keyword(s):  
Transition Metal ◽  
Crystalline Structure ◽  
Large Scale ◽  
Sodium Ion ◽  
Sodium Ion Battery ◽  
Transition Metal Dichalcogenide ◽  
High Quality ◽  
Single Crystalline ◽  
Scalable Synthesis

High-quality 2D WS2, MoS2, MoSe2 and WSe2 nanosheets with a single-crystalline structure have been synthesized on a large scale by a NaCl template-assisted strategy.

One-pot synthesis of single-crystalline PtPb nanodendrites with enhanced activity for electrooxidation of formic acid

2016 ◽  
Vol 52 (24) ◽  
pp. 4493-4496 ◽  
Author(s):  
Ximing Qu ◽  
Zhenming Cao ◽  
Binwei Zhang ◽  
XiaoChun Tian ◽  
Fuchun Zhu ◽  
...  
Keyword(s):  
Formic Acid ◽  
Crystalline Structure ◽  
One Pot ◽  
Single Crystalline ◽  
One Pot Synthesis ◽  
Enhanced Activity

Bimetallic PtPb nanodendrites with a single-crystalline structure were obtained by a facile one-pot strategy.

Atomically Architected Silicon Pyramid Single-Crystalline Structure Supporting Epitaxial Material Growth and Characteristic Magnetism

2021 ◽  
Author(s):  
Aydar Irmikimov ◽  
Liliany N. Pamasi ◽  
Azusa N. Hattori ◽  
Takaaki Higashi ◽  
Shunta Takahashi ◽  
...  
Keyword(s):  
Crystalline Structure ◽  
Single Crystalline ◽  
Material Growth
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