Symmetry Breaking during Seeded Growth of Nanocrystals

Nano Letters ◽  
2012 ◽  
Vol 12 (11) ◽  
pp. 6038-6042 ◽  
Author(s):  
Xiaohu Xia ◽  
Younan Xia
Keyword(s):  
Symmetry Breaking ◽  
Seeded Growth

scholarly journals Symmetry Breaking by Surface Blocking: Synthesis of Bimorphic Silver Nanoparticles, Nanoscale Fishes and Apples

2016 ◽  
Vol 6 (1) ◽  
Author(s):  
Nicole Cathcart ◽  
Vladimir Kitaev
Keyword(s):  
Silver Nanoparticles ◽  
Acrylic Acid ◽  
Symmetry Breaking ◽  
Metal Nanoparticle ◽  
Shape Design ◽  
Seeded Growth ◽  
Nanoparticle Growth ◽  
Powerful Approach ◽  
Advanced Applications ◽  
Nucleation Point

Abstract A powerful approach to augment the diversity of well-defined metal nanoparticle (MNP) morphologies, essential for MNP advanced applications, is symmetry breaking combined with seeded growth. Utilizing this approach enabled the formation of bimorphic silver nanoparticles (bi-AgNPs) consisting of two shapes linked by one regrowth point. Bi-AgNPs were formed by using an adsorbing polymer, poly(acrylic acid), PAA, to block the surface of a decahedral AgNP seed and restricting growth of new silver to a single nucleation point. First, we have realized 2-D growth of platelets attached to decahedra producing nanoscale shapes reminiscent of apples, fishes, mushrooms and kites. 1-D bimorphic growth of rods (with chloride) and 3-D bimorphic growth of cubes and bipyramids (with bromide) were achieved by using halides to induce preferential (100) stabilization over (111) of platelets. Furthermore, the universality of the formation of bimorphic nanoparticles was demonstrated by using different seeds. Bi-AgNPs exhibit strong SERS enhancement due to regular cavities at the necks. Overall, the reported approach to symmetry breaking and bimorphic nanoparticle growth offers a powerful methodology for nanoscale shape design.

scholarly journals Disconnecting Symmetry Breaking from Seeded Growth for the Reproducible Synthesis of High Quality Gold Nanorods

ACS Nano ◽  
2019 ◽  
Vol 13 (4) ◽  
pp. 4424-4435 ◽  
Author(s):  
Guillermo González-Rubio ◽  
Vished Kumar ◽  
Pablo Llombart ◽  
Pablo Díaz-Núñez ◽  
Eva Bladt ◽  
...  
Keyword(s):  
Symmetry Breaking ◽  
Gold Nanorods ◽  
Seeded Growth ◽  
High Quality

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.

Symmetry breaking in convergent-beam diffraction

1989 ◽  
Vol 47 ◽  
pp. 480-481
Author(s):  
D.J. Eaglesham
Keyword(s):  
Symmetry Breaking ◽  
Point Group ◽  
X Ray Diffraction ◽  
Multiple Diffraction ◽  
Space Groups ◽  
Atomic Displacements ◽  
Small Probe ◽  
Phase Sensitive ◽  
Convergent Beam

Convergent Beam Electron Diffraction is now almost routinely used in the determination of the point- and space-groups of crystalline samples. In addition to its small-probe capability, CBED is also postulated to be more sensitive than X-ray diffraction in determining crystal symmetries. Multiple diffraction is phase-sensitive, so that the distinction between centro- and non-centro-symmetric space groups should be trivial in CBED: in addition, the stronger scattering of electrons may give a general increase in sensitivity to small atomic displacements. However, the sensitivity of CBED symmetry to the crystal point group has rarely been quantified, and CBED is also subject to symmetry-breaking due to local strains and inhomogeneities. The purpose of this paper is to classify the various types of symmetry-breaking, present calculations of the sensitivity, and illustrate symmetry-breaking by surface strains.CBED symmetry determinations usually proceed by determining the diffraction group along various zone axes, and hence finding the point group. The diffraction group can be found using either the intensity distribution in the discs

Centrosome Aurora A gradient ensures single polarity axis in C. elegans embryos

2020 ◽  
Vol 48 (3) ◽  
pp. 1243-1253 ◽  
Author(s):  
Sukriti Kapoor ◽  
Sachin Kotak
Keyword(s):  
Symmetry Breaking ◽  
Cell Fate ◽  
Cell Cortex ◽  
Axis Formation ◽  
Aurora A Kinase ◽  
Aurora A ◽  
C Elegans ◽  
Cell Embryo ◽  
Polarity Establishment

Cellular asymmetries are vital for generating cell fate diversity during development and in stem cells. In the newly fertilized Caenorhabditis elegans embryo, centrosomes are responsible for polarity establishment, i.e. anterior–posterior body axis formation. The signal for polarity originates from the centrosomes and is transmitted to the cell cortex, where it disassembles the actomyosin network. This event leads to symmetry breaking and the establishment of distinct domains of evolutionarily conserved PAR proteins. However, the identity of an essential component that localizes to the centrosomes and promotes symmetry breaking was unknown. Recent work has uncovered that the loss of Aurora A kinase (AIR-1 in C. elegans and hereafter referred to as Aurora A) in the one-cell embryo disrupts stereotypical actomyosin-based cortical flows that occur at the time of polarity establishment. This misregulation of actomyosin flow dynamics results in the occurrence of two polarity axes. Notably, the role of Aurora A in ensuring a single polarity axis is independent of its well-established function in centrosome maturation. The mechanism by which Aurora A directs symmetry breaking is likely through direct regulation of Rho-dependent contractility. In this mini-review, we will discuss the unconventional role of Aurora A kinase in polarity establishment in C. elegans embryos and propose a refined model of centrosome-dependent symmetry breaking.

A Symmetry-Breaking Theory of False Pop Out

2011 ◽  
Author(s):  
Kimberley D. Orsten ◽  
Mary C. Portillo ◽  
James R. Pomerantz
Keyword(s):  
Symmetry Breaking
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