scholarly journals Nanoscale Mapping of Heterogeneous Strain and Defects in Individual Magnetic Nanocrystals

Crystals ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 658
Author(s):  
Xiaowen Shi ◽  
Ross Harder ◽  
Zhen Liu ◽  
Oleg Shpyrko ◽  
Eric Fullerton ◽  
...  
Keyword(s):  
Uniform Distribution ◽  
Displacement Field ◽  
Density Functional ◽  
Core Region ◽  
Outer Shell ◽  
Core Shell ◽  
Diffractive Imaging ◽  
The Core ◽  
Partial Dislocations ◽  
Distribution Of Magnetization

We map the three-dimensional strain heterogeneity within a single core-shell Ni nanoparticle using Bragg coherent diffractive imaging. We report the direct observation of both uniform displacements and strain within the crystalline core Ni region. We identify non-uniform displacements and dislocation morphologies across the core–shell interface, and within the outer shell at the nanoscale. By tracking individual dislocation lines in the outer shell region, and comparing the relative orientation between the Burgers vector and dislocation lines, we identify full and partial dislocations. The full dislocations are consistent with elasticity theory in the vicinity of a dislocation while the partial dislocations deviate from this theory. We utilize atomistic computations and Landau–Lifshitz–Gilbert simulation and density functional theory to confirm the equilibrium shape of the particle and the nature of the (111) displacement field obtained from Bragg coherent diffraction imaging (BCDI) experiments. This displacement field distribution within the core-region of the Ni nanoparticle provides a uniform distribution of magnetization in the core region. We observe that the absence of dislocations within the core-regions correlates with a uniform distribution of magnetization projections. Our findings suggest that the imaging of defects using BCDI could be of significant importance for giant magnetoresistance devices, like hard disk-drive read heads, where the presence of dislocations can affect magnetic domain wall pinning and coercivity.

scholarly journals Selective Cation Exchange in the Core Region of Cu2–xSe/Cu2–xS Core/Shell Nanocrystals

2015 ◽  
Vol 137 (38) ◽  
pp. 12195-12198 ◽  
Author(s):  
Karol Miszta ◽  
Graziella Gariano ◽  
Rosaria Brescia ◽  
Sergio Marras ◽  
Francesco De Donato ◽  
...  
Keyword(s):  
Cation Exchange ◽  
Core Region ◽  
Core Shell ◽  
The Core

Boron clusters with 46, 48, and 50 atoms: competition among the core–shell, bilayer and quasi-planar structures

Nanoscale ◽  
2017 ◽  
Vol 9 (37) ◽  
pp. 13905-13909 ◽  
Author(s):  
Linwei Sai ◽  
Xue Wu ◽  
Nan Gao ◽  
Jijun Zhao ◽  
R. Bruce King
Keyword(s):  
Genetic Algorithm ◽  
Density Functional Theory ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Global Search ◽  
Core Shell ◽  
Functional Theory ◽  
Boron Clusters ◽  
The Core ◽  
Planar Structures

Using a genetic algorithm combined with density functional theory calculations, we perform a global search for the lowest-energy structures of Bnclusters withn= 46, 48, 50.

In vivo and in vitro comparison of three astilbin encapsulated zein nanoparticles with different outer shell

2021 ◽  
Author(s):  
Yi-Ting Ruan ◽  
Wenjun Wang ◽  
Guodong Zheng ◽  
Zhong-Ping Yin ◽  
Ji-Guang Chen ◽  
...  
Keyword(s):  
Sodium Caseinate ◽  
Outer Shell ◽  
Core Shell ◽  
The Core ◽  
In Vitro Comparison

Three shell materials, lecithin (ZNP-L), chitosan (ZNP-CH) and sodium caseinate (ZNP-SC), were used to prepared the core-shell zein nanoparticles. Astilbin was encapsulated as a model flavonoid to compared the influence...

scholarly journals Computational high-throughput screening of alloy nanoclusters for electrocatalytic hydrogen evolution

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Xinnan Mao ◽  
Lu Wang ◽  
Yafeng Xu ◽  
Pengju Wang ◽  
Youyong Li ◽  
...  
Keyword(s):  
Hydrogen Evolution ◽  
High Throughput ◽  
High Throughput Screening ◽  
Active Sites ◽  
Density Functional ◽  
Screening Method ◽  
Machine Learning Techniques ◽  
Core Shell ◽  
The Core ◽  
Alloy Clusters

AbstractHere, we report a density functional theory (DFT)-based high-throughput screening method to successfully identify a type of alloy nanoclusters as the electrocatalyst for hydrogen evolution reaction (HER). Totally 7924 candidates of Cu-based alloy clusters of Cu55-nMn (M = Co, Ni, Ru, and Rh) are optimized and evaluated to screening for the promising catalysts. By comparing different structural patterns, Cu-based alloy clusters prefer the core–shell structures with the dopant metal in the core and Cu as the shell atoms. Generally speaking, the HER performance of the Cu-based nanoclusters can be significantly improved by doping transition metals, and the active sites are the bridge sites and three-fold sites on the outer-shell Cu atoms. Considering the structural stability and the electrochemical activity, core–shell CuNi alloy clusters are suggested to be the superior electrocatalyst for hydrogen evolution. A descriptor composing of surface charge is proposed to efficiently evaluate the HER activity of the alloy clusters supported by the DFT calculations and machine-learning techniques. Our screening strategy could accelerate the pace of discovery for promising HER electrocatalysts using metal alloy nanoclusters.

scholarly journals Microstructural Evolution from Dendrites to Core-Shell Equiaxed Grain Morphology for CoCrFeNiVx High-Entropy Alloys in Metallic Casting Mold

Metals ◽  
2019 ◽  
Vol 9 (11) ◽  
pp. 1172 ◽  
Author(s):  
Leigang Cao ◽  
Lin Zhu ◽  
Hongde Shi ◽  
Zerui Wang ◽  
Yue Yang ◽  
...  
Keyword(s):  
Grain Morphology ◽  
Core Region ◽  
Core Shell ◽  
High Entropy Alloys ◽  
Σ Phase ◽  
High Entropy ◽  
The Core ◽  
Interdendrite Region ◽  
Fcc Phase ◽  
Equiaxed Grain

The CoCrFeNiVx (x = 0, 0.25, 0.5, 0.7, 0.8, 0.9, and 1.0) high-entropy alloys (HEAs) were fabricated by the copper mold casting process. The microstructure, phase constitution, and mechanical properties were investigated by using X-ray diffraction, scanning electron microscopy, transmission electron microscopy analyses and compressive testing. It revealed that, when x ≤ 0.25, the alloys solidified into a single fcc phase. When 0.5 ≤ x ≤ 0.8, the alloys solidified into a dendritic structure of the fcc phase with the formation of the σ phase in the interdendrite region. Interestingly, when x exceeded 0.9, the alloys presented a typical core-shell equiaxed grain morphology. The core region consisting of a mixture of fcc + σ phases was surrounded by the shell of the single σ phase and the interdendrite region solidified into the single fcc phase. The dual-phase “eutectiod” structure in the core region of the equiaxed grain might be formed from the decomposition of the unidentified metastable phase. As the V fraction increased, the compressive yield strength of the CoCrFeNiVx alloys gradually increased from 164 MPa (x = 0) to 458 MPa (x = 0.8), and then sharply increased to 722 MPa (x = 0.9) and 1493 MPa (x = 1.0).

Polymer@MOF@MOF: “grafting from” atom transfer radical polymerization for the synthesis of hybrid porous solids

2015 ◽  
Vol 51 (60) ◽  
pp. 11994-11996 ◽  
Author(s):  
Kyle A. McDonald ◽  
Jeremy I. Feldblyum ◽  
Kyoungmoo Koh ◽  
Antek G. Wong-Foy ◽  
Adam J. Matzger
Keyword(s):  
Atom Transfer Radical Polymerization ◽  
Radical Polymerization ◽  
Outer Shell ◽  
Polymer Chains ◽  
Porous Solids ◽  
Core Shell ◽  
Atom Transfer ◽  
Hybrid Polymer ◽  
The Core ◽  
Grafting From

PMMA@IRMOF-3@MOF-5, a hybrid polymer–MOF composite, was produced through a combination of core–shell and post-synthetic modification techniques. The core–shell architecture allows polymer chains to be tethered to the outer shell selectively.

Theoretical study of the stability of Bep@Rbq core-shell clusters

2013 ◽  
Vol 91 (9) ◽  
pp. 832-838 ◽  
Author(s):  
Yan Sun ◽  
René Fournier
Keyword(s):  
Charge Separation ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Lower Surface ◽  
Outer Shell ◽  
Shell Structures ◽  
Core Shell ◽  
Prototype System ◽  
Surface Charges ◽  
The Difference

Core-shell structures Ap@Bq can be energetically favored in bimetallic clusters when B has a lower surface energy than A, and p and q are chosen such that a single and complete outer shell of q atoms of B can form around the Ap core. If the difference in the electronegativities of A and B is large, one expects significant charge separation between the A core and the B shell. The combination of a closed atomic shell of B atoms and surface charges (core-shell charge separation) should impart stability on this type of Ap@Bq clusters. We report results of density functional theory calculations, including global optimization of cluster geometries, to characterize the prototype system BepRbq. Our calculations show that BepRbq clusters indeed adopt core-shell structures. However, they do not have particularly large surface charges and are unstable against coalescence. Surprisingly, the Rbq outer shell carries a net negative charge. This can be interpreted as the analog, for clusters, of electron spill-out at semi-infinite jellium surfaces, and it probably results from the electrons’ kinetic pressure.

Intramitochondrial Viruses of Reptilian Cell Origin

1972 ◽  
Vol 30 ◽  
pp. 318-319
Author(s):  
Philip D. Lunger ◽  
H. Fred Clark
Keyword(s):  
Particle Production ◽  
Outer Zone ◽  
Density Variation ◽  
Core Region ◽  
Mitochondrial Membranes ◽  
Virus Particles ◽  
The Core ◽  
Vipera Russelli ◽  
Maturation Stages ◽  
Type Particle

In the course of fine structure studies of spontaneous “C-type” particle production in a viper (Vipera russelli) spleen cell line, designated VSW, virus particles were frequently observed within mitochondria. The latter were usually enlarged or swollen, compared to virus-free mitochondria, and displayed a considerable degree of cristae disorganization.Intramitochondrial viruses measure 90 to 100 mμ in diameter, and consist of a nucleoid or core region of varying density and measuring approximately 45 mμ in diameter. Nucleoid density variation is presumed to reflect varying degrees of condensation, and hence maturation stages. The core region is surrounded by a less-dense outer zone presumably representing viral capsid.Particles are usually situated in peripheral regions of the mitochondrion. In most instances they appear to be lodged between loosely apposed inner and outer mitochondrial membranes.

Magnetic Properties of Fe3O4/CoFe2O4 Composite Nanoparticles with Core/Shell Architecture

2020 ◽  
Vol 65 (10) ◽  
pp. 904
Author(s):  
V. O. Zamorskyi ◽  
Ya. M. Lytvynenko ◽  
A. M. Pogorily ◽  
A. I. Tovstolytkin ◽  
S. O. Solopan ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Spinel Ferrite ◽  
Composite Nanoparticles ◽  
Core Shell ◽  
Cofe2o4 Nanoparticles ◽  
Core Diameter ◽  
The Core ◽  
Shell Particles ◽  
Interface Parameters ◽  
Shell Composite

Magnetic properties of the sets of Fe3O4(core)/CoFe2O4(shell) composite nanoparticles with a core diameter of about 6.3 nm and various shell thicknesses (0, 1.0, and 2.5 nm), as well as the mixtures of Fe3O4 and CoFe2O4 nanoparticles taken in the ratios corresponding to the core/shell material contents in the former case, have been studied. The results of magnetic research showed that the coating of magnetic nanoparticles with a shell gives rise to the appearance of two simultaneous effects: the modification of the core/shell interface parameters and the parameter change in both the nanoparticle’s core and shell themselves. As a result, the core/shell particles acquire new characteristics that are inherent neither to Fe3O4 nor to CoFe2O4. The obtained results open the way to the optimization and adaptation of the parameters of the core/shell spinel-ferrite-based nanoparticles for their application in various technological and biomedical domains.

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