scholarly journals Tuning the Dielectric Response in a Nanocomposite Material through Nanoparticle Morphology

2021 ◽  
Author(s):  
Archita Adluri ◽  
Brett Henderson ◽  
Irina Paci
Keyword(s):  
Metal Cluster ◽  
Periodic Boundary Conditions ◽  
Nanoparticle Size ◽  
Modern Theory ◽  
Quantum Properties ◽  
High K ◽  
Molecular Scale ◽  
The Matrix ◽  
Nanoparticle Morphology ◽  
Molecular Nanoparticles

The introduction of metal cluster dopants and molecular-scale inclusions in metal oxide matrices provides an opportunity for exploring new high-k solid-state dielectrics with tunable response. The quantum properties of molecular nanoparticles depend strongly on their size and shape, a characteristic that can be exploited in changing the response properties of a material, while the small nanoparticle size can help limit the usual issues of conduction and leakage. Here, we model the polarization of molecular-scale silver inclusions in magnesium oxide, using the Modern Theory of Polarization and Car-Parinello Molecular Dynamics (CPMD). Several trends are considered, including nanoparticle size, shape and orientation relative to the applied field. Dielectric permittivity enhancements of 30-100% were observed with inclusion sizes varying from 8 to 32 atoms, considering both rod-like and disk-like inclusions, with alignment either parallel or perpendicular to the external field. Currents calculated using the modern theory of polarization with periodic boundary conditions can experience box edge jumps due to the distortion of the matrix during the simulations - an approach for addressing these issues in CPMD calculations is outlined within.

scholarly journals Effect of Nanoparticle Size on the Mechanical Strength of Ni–Graphene Composites

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 3087
Author(s):  
Karina A. Krylova ◽  
Liliya R. Safina ◽  
Ramil T. Murzaev ◽  
Julia A. Baimova ◽  
Radik R. Mulyukov
Keyword(s):  
Nickel Nanoparticles ◽  
Dynamics Simulation ◽  
Nanoparticle Size ◽  
Strain Behavior ◽  
Graphene Composite ◽  
Graphene Flakes ◽  
Property Anisotropy ◽  
The Matrix ◽  
Material Volume ◽  
Crumpled Graphene

The effect of the size of nickel nanoparticles on the fabrication of a Ni–graphene composite by hydrostatic pressure at 0 K followed by annealing at 1000 and 2000 K is studied by molecular dynamics simulation. Crumpled graphene, consisting of crumpled graphene flakes interconnected by van der Waals forces is chosen as the matrix for the composite and filled with nickel nanoparticles composed of 21 and 47 atoms. It is found that the main factors that affect composite fabrication are nanoparticle size, the orientation of the structural units, and temperature of the fabrication process. The best stress–strain behavior is achieved for the Ni/graphene composite with Ni47 nanoparticle after annealing at 2000 K. However, all of the composites obtained had strength property anisotropy due to the inhomogeneous distribution of pores in the material volume.

CONSTRUCTION OF A PHYSICAL AND MATHEMATICAL MODEL OF THE GRAVITATIONAL FIELD

2021 ◽  
Vol 73 (1) ◽  
pp. 91-95
Author(s):  
L.G. Kassenova ◽  
◽  
G.S. Yensebaeva ◽  
G.Zh. Shuitenov ◽  
◽  
...  
Keyword(s):  
Gravitational Field ◽  
Test Particle ◽  
Quantum Physics ◽  
Hubble Constant ◽  
Space Time ◽  
Modern Theory ◽  
Quantum Properties ◽  
Centrally Symmetric ◽  
The Relationship ◽  
Time Continuum

The problem of gravitational field physics is to identify the relationship between the gravitational field and the expansion of the space-time continuum. Therefore, the creation of models, the study of which makes it possible to identify these relationships and express them in formulas, is relevant. In the modern theory of the gravitational field, small quantities appear, which are neglected in the derivation of formulas of practical application. This paper presents a model of the gravitational field that combines quantum properties with the expansion of the space-time continuum. Also, using a simplified model of the coordinate system, the gravitational field of a stationary centrally symmetric object is studied and the limiting distance of the test particle capture by the gravitational field is calculated. Calculations made without neglecting small quantities gave interesting results: the limiting radius of capture by the gravitational field of the test particle; the formula for the mass defect of the black hole Schwarzschild; relations expressing the dependence of the quantities of quantum physics on the Hubble constant.

Low-frequency polarization in molecular-scale noble-metal/metal–oxide nanocomposites

Nanoscale ◽  
2018 ◽  
Vol 10 (20) ◽  
pp. 9583-9593 ◽  
Author(s):  
David J. T. Hally ◽  
Irina Paci
Keyword(s):  
Metal Oxide ◽  
Noble Metal ◽  
Low Frequency ◽  
Modern Theory ◽  
New Methods ◽  
Polarization Response ◽  
Metal Metal ◽  
Molecular Scale

New methods for calculating the polarization response in metal/metal–oxide nanocomposites using the Modern Theory of Polarization, with partitioning into inclusion and matrix contributions.

scholarly journals Ultraviolet and Infrared luminescent Au-rich nanostructure growth in SiO2 by burrowing and inverse Oswald ripening process

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
D. P. Datta ◽  
A. Chettah ◽  
Arpan Maiti ◽  
B. Satpati ◽  
P. K. Sahoo
Keyword(s):  
Ion Irradiation ◽  
Metal Layer ◽  
Silica Matrix ◽  
Infrared Range ◽  
Thermal Spike Model ◽  
Spike Model ◽  
Initial Stage ◽  
The Matrix ◽  
Surface Enhanced Raman ◽  
Nanoparticle Morphology

Abstract We study the evolution of nanoparticle morphology through successive stages when Au-Si bilayer on SiO2 is irradiated with 500 keV Xe-ions and resulting luminescence in the UV, Visible and infrared range. An array of nanoscale island morphology is developed on the silica surface in the initial stage of evolution which undergoes gradual burrowing in the silica matrix accompanied by elongation of large ones in the direction of incident ions under cumulative ion irradiation. Burrowing is found to occur in order to minimize the surface free energy of the nanoparticles. Numerical simulation based on the unified thermal spike model shows formation of molten latent tracks due to ions energy release which drive the dewetting of the metal layer and further give mobility to nanoparticle atoms leading to burrowing in the later stage of evolution and elongation of large nanoparticles. Satellite nanoparticles are observed to grow around Au nanoparticles embedded in silica through nucleation of Au atoms dissolved in the matrix by incident ions. The varying diameters of the Au satellite nanoparticles seem to result in luminescence in the UV and infrared range. The observed structure may find application in surface enhanced Raman scattering, catalysis, and LEDs.

Crystalloid Inclusions in Hepatocyte Mitochondria and Their Similarity to Cytoplasmic Crystalloids

1974 ◽  
Vol 32 ◽  
pp. 198-199
Author(s):  
Odell T. Minick ◽  
Hidejiro Yokoo
Keyword(s):  
Liver Disease ◽  
Alcoholic Liver Disease ◽  
Special Interest ◽  
Structural Variations ◽  
Mitochondrial Alterations ◽  
The Matrix ◽  
Crystalloid Inclusions ◽  
Liver Biopsies

Mitochondrial alterations were studied in 25 liver biopsies from patients with alcoholic liver disease. Of special interest were the morphologic resemblance of certain fine structural variations in mitochondria and crystalloid inclusions. Four types of alterations within mitochondria were found that seemed to relate to cytoplasmic crystalloids.Type 1 alteration consisted of localized groups of cristae, usually oriented in the long direction of the organelle (Fig. 1A). In this plane they appeared serrated at the periphery with blind endings in the matrix. Other sections revealed a system of equally-spaced diagonal lines lengthwise in the mitochondrion with cristae protruding from both ends (Fig. 1B). Profiles of this inclusion were not unlike tangential cuts of a crystalloid structure frequently seen in enlarged mitochondria described below.

Coherency loss in γ' precipitates in nickel-base superalloy

1983 ◽  
Vol 41 ◽  
pp. 244-245
Author(s):  
R. A. Ricks ◽  
Angus J. Porter
Keyword(s):  
Lattice Mismatch ◽  
Lattice Parameter ◽  
Nickel Base Superalloy ◽  
Large Size ◽  
The Matrix ◽  
Nimonic 80A ◽  
Interfacial Dislocations ◽  
Nickel Base ◽  
Coherency Loss ◽  
Nimonic 115

During a recent investigation concerning the growth of γ' precipitates in nickel-base superalloys it was observed that the sign of the lattice mismatch between the coherent particles and the matrix (γ) was important in determining the ease with which matrix dislocations could be incorporated into the interface to relieve coherency strains. Thus alloys with a negative misfit (ie. the γ' lattice parameter was smaller than the matrix) could lose coherency easily and γ/γ' interfaces would exhibit regularly spaced networks of dislocations, as shown in figure 1 for the case of Nimonic 115 (misfit = -0.15%). In contrast, γ' particles in alloys with a positive misfit could grow to a large size and not show any such dislocation arrangements in the interface, thus indicating that coherency had not been lost. Figure 2 depicts a large γ' precipitate in Nimonic 80A (misfit = +0.32%) showing few interfacial dislocations.

Influence of Heat Treatments on Microstructures in an Fe-Co-V Alloy

1974 ◽  
Vol 32 ◽  
pp. 512-513
Author(s):  
S. Mahajan ◽  
M. R. Pinnel ◽  
J. E. Bennett
Keyword(s):  
Single Phase ◽  
Alloy Composition ◽  
Supersaturated Solid Solution ◽  
Cell Formation ◽  
Heat Treatments ◽  
Air Cooling ◽  
Iced Brine ◽  
Transmission Electron ◽  
The Matrix ◽  
Bcc Structure

The microstructural changes in an Fe-Co-V alloy (composition by wt.%: 2.97 V, 48.70 Co, 47.34 Fe and balance impurities, such as C, P and Ni) resulting from different heat treatments have been evaluated by optical metallography and transmission electron microscopy. Results indicate that, on air cooling or quenching into iced-brine from the high temperature single phase ϒ (fcc) field, vanadium can be retained in a supersaturated solid solution (α2) which has bcc structure. For the range of cooling rates employed, a portion of the material appears to undergo the γ-α2 transformation massively and the remainder martensitically. Figure 1 shows dislocation topology in a region that may have transformed martensitically. Dislocations are homogeneously distributed throughout the matrix, and there is no evidence for cell formation. The majority of the dislocations project along the projections of <111> vectors onto the (111) plane, implying that they are predominantly of screw character.

Heterogeneity of Size and Distribution of Intramembrane Particles in the Plasma Membrane of Yeast

1977 ◽  
Vol 35 ◽  
pp. 596-597
Author(s):  
E. Keyhani
Keyword(s):  
Plasma Membrane ◽  
Candida Utilis ◽  
Synthetic Medium ◽  
Freeze Fracture ◽  
Translational Diffusion ◽  
Yeast Cells ◽  
Distilled Water ◽  
Intramembrane Particles ◽  
The Matrix ◽  
Water Cell

The matrix of biological membranes consists of a lipid bilayer into which proteins or protein aggregates are intercalated. Freeze-fracture techni- ques permit these proteins, perhaps in association with lipids, to be visualized in the hydrophobic regions of the membrane. Thus, numerous intramembrane particles (IMP) have been found on the fracture faces of membranes from a wide variety of cells (1-3). A recognized property of IMP is their tendency to form aggregates in response to changes in experi- mental conditions (4,5), perhaps as a result of translational diffusion through the viscous plane of the membrane. The purpose of this communica- tion is to describe the distribution and size of IMP in the plasma membrane of yeast (Candida utilis).Yeast cells (ATCC 8205) were grown in synthetic medium (6), and then harvested after 16 hours of culture, and washed twice in distilled water. Cell pellets were suspended in growth medium supplemented with 30% glycerol and incubated for 30 minutes at 0°C, centrifuged, and prepared for freeze-fracture, as described earlier (2,3).

Electron microscopy and diffraction studies of polyimides

1983 ◽  
Vol 41 ◽  
pp. 28-29
Author(s):  
O.C. de Hodgins ◽  
K. R. Lawless ◽  
R. Anderson
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Structural Features ◽  
Inert Atmosphere ◽  
Polyimide Films ◽  
Resolution Electron ◽  
The Matrix ◽  
High Resolution Electron Microscope ◽  
Diffraction Patterns ◽  
Polymeric Samples

Commercial polyimide films have shown to be homogeneous on a scale of 5 to 200 nm. The observation of Skybond (SKB) 705 and PI5878 was carried out by using a Philips 400, 120 KeV STEM. The objective was to elucidate the structural features of the polymeric samples. The specimens were spun and cured at stepped temperatures in an inert atmosphere and cooled slowly for eight hours. TEM micrographs showed heterogeneities (or nodular structures) generally on a scale of 100 nm for PI5878 and approximately 40 nm for SKB 705, present in large volume fractions of both specimens. See Figures 1 and 2. It is possible that the nodulus observed may be associated with surface effects and the structure of the polymers be regarded as random amorphous arrays. Diffraction patterns of the matrix and the nodular areas showed different amorphous ring patterns in both materials. The specimens were viewed in both bright and dark fields using a high resolution electron microscope which provided magnifications of 100,000X or more on the photographic plates if desired.

Organisation in the Structure of the Cytoplasmic Ground Substance

1978 ◽  
Vol 36 (3) ◽  
pp. 627-639
Author(s):  
K.R. Porter
Keyword(s):  
Endoplasmic Reticulum ◽  
Golgi Complex ◽  
Random Distribution ◽  
Ground Substance ◽  
The Matrix ◽  
Cell Processes ◽  
Cytoplasmic Ground Substance

Most types of cells are known from their structure and overall form to possess a characteristic organization. In some instances this is evident in the non-random disposition of organelles and such system subunits as cisternae of the endoplasmic reticulum or the Golgi complex. In others it appears in the distribution and orientation of cytoplasmic fibrils. And in yet others the organization finds expression in the non-random distribution and orientation of microtubules, especially as found in highly anisometric cells and cell processes. The impression is unavoidable that in none of these cases is the organization achieved without the involvement of the cytoplasmic ground substance (CGS) or matrix. This impression is based on the fact that a matrix is present and that in all instances these formed structures, whether membranelimited or filamentous, are suspended in it. In some well-known instances, as in arrays of microtubules which make up axonemes and axostyles, the matrix resolves itself into bridges (and spokes) between the microtubules, bridges which are in some cases very regularly disposed and uniform in size (Mcintosh, 1973; Bloodgood and Miller, 1974; Warner and Satir, 1974).

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