scholarly journals Raman active modes of single-wall boron nitride nanotubes inside carbon nanotubes

2018 ◽  
Vol 3 (2) ◽  
Author(s):  
A.M. Nassir ◽  
Ah Rahmani ◽  
M. Boutahir ◽  
B. Fakrach ◽  
H. Chadli ◽  
...  
Keyword(s):  
Boron Nitride ◽  
Inelastic Neutron Scattering ◽  
Large Diameter ◽  
Chemical Properties ◽  
Spatial Dimension ◽  
Inelastic Neutron ◽  
Boron Nitride Nanotubes ◽  
Hybrid Nanostructures ◽  
Wave Number ◽  
Physical And Chemical

The structure of boron–nitride nanotubes (BNNTs) is very similar to that of CNTs, and they exhibit many similar physical and chemical properties. In particular, a single walled boron nitride nanotube (BNNT) and a single walled carbon nanotube (CNT) have been reported. The spectral moment’s method (SMM) was shown to be a powerful tool for determining vibrational spectra (infrared absorption, Raman scattering and inelastic neutron-scattering spectra) of harmonic systems. This method can be applied to very large systems, whatever the type of atomic forces, the spatial dimension, and structure of the material. The calculations of vibrational properties of BNNT@CNT double-walled hybrid nanostructures are performed in the framework of the force constants model, using the spectral moment's method (SMM). A Lennard–Jones potential is used to describe the van der Waals in-teractions between inner and outer tubes in hybrid systems. The calculation of the BNNT@CNT Raman active modes as a function of the diameter and chirality of the inner and outer tubes allows us to derive the diameter dependence of the wave number of the breathing-like modes, intermediate-like modes and tangential-like modes in a large diameter range. These predictions are useful to interpret the experimental data.

scholarly journals Basic Materials Studies of Lanthanide Halide Scintillators

2007 ◽  
Vol 1038 ◽  
Author(s):  
F. P. Doty ◽  
Douglas McGregor ◽  
Mark Harrison ◽  
Kip Findley ◽  
Raulf Polichar ◽  
...  
Keyword(s):  
Gamma Ray ◽  
Materials Science ◽  
Low Cost ◽  
Large Diameter ◽  
Scale Up ◽  
Chemical Properties ◽  
Anisotropic Plasticity ◽  
Ongoing Work ◽  
Perfect Cleavage ◽  
Physical And Chemical

AbstractCerium and lanthanum tribromides and trichlorides form isomorphous alloys with the hexagonal UCl3 type structure, and have been shown to exhibit high luminosity and proportional response, making them attractive alternatives for room temperature gamma ray spectroscopy. However the fundamental physical and chemical properties of this system introduce challenges for material processing, scale-up, and detector fabrication. In particular, low fracture stress and perfect cleavage along prismatic planes cause profuse cracking during and after crystal growth, impeding efforts to scale this system for production of low cost, large diameter spectrometers. We have reported progress on basic materials science of the lanthanide halides. Studies to date have included thermomechanical and thermogravimetric analyses, hygroscopicity, yield strength, and fracture toughness. The observed mechanical properties pose challenging problems for material production and post processing; therefore, understanding mechanical behavior is key to fabricating large single crystals, and engineering of robust detectors and systems. Analysis of the symmetry and crystal structure of this system, including identification of densely-packed and electrically neutral planes with slip and cleavage, and comparison of relative formation and propagation energies for proposed slip systems, suggest possible mechanisms for deformation and crack initiation under stress. The low c/a ratio and low symmetry relative to traditional scintillators indicate limited and highly anisotropic plasticity cause redistribution of residual process stress to cleavage planes, initiating fracture. Ongoing work to develop fracture resistant lanthanide halides is presented.

scholarly journals Bonding of Gold Nanoclusters on Graphene with and without Point Defects

Nanomaterials ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 2109
Author(s):  
Theodoros Pavloudis ◽  
Joseph Kioseoglou ◽  
Richard E. Palmer
Keyword(s):  
Gold Nanoclusters ◽  
Chemical Properties ◽  
Binding Energies ◽  
Hybrid Nanostructures ◽  
Au Nps ◽  
Device Stability ◽  
Spin Polarized ◽  
Technology Applications ◽  
Physical And Chemical ◽  
Electronic Chemical

Hybrid nanostructures of size-selected nanoparticles (NPs) and 2D materials exhibit striking physical and chemical properties and are attractive for many technology applications. A major issue for the performance of these applications is device stability. In this work, we investigate the bonding of cuboctahedral, decahedral and icosahedral Au NPs comprising 561 atoms on graphene sheets via 103-atom scale ab initio spin-polarized calculations. Two distinct cases we considered: (i) the Au NPs sit with their (111) facets on graphene and (ii) the NPs are oriented with a vertex on graphene. In both cases, we compare the binding energies with and without a graphene vacancy under the NP. We find that in all cases, the presence of the graphene vacancy enhances the bonding of the NPs. Significantly, in the vertex-on-graphene case, the binding energy is considerably increased by several eVs and becomes similar to the (111) facet-on-graphene case. The strain in the NPs is found to be minimal and the displacement of the carbon atoms in the immediate neighborhood of the vacancy is on the 0.1 Å scale. The work suggests the creation of stable NP-graphene systems for a variety of electronic, chemical and photonic applications.

Hybrid Nanostructures

2016 ◽  
pp. 231-275 ◽  
Author(s):  
Ahmed Nabile Emam ◽  
Ahmed Sadek Mansour ◽  
Emad Girgis ◽  
Mona Bakr Mohamed
Keyword(s):  
Chemical Properties ◽  
Hybrid Nanostructures ◽  
Hybrid Nanocomposites ◽  
Physical And Chemical Properties ◽  
Hybrid Nanostructure ◽  
High Quality ◽  
Graphene Nanocomposites ◽  
Nanostructure Materials ◽  
Physico Chemical ◽  
Physical And Chemical

The recent extensive interest of nanostructure materials associated with their unique properties is motivated to develop new hybrid nanocomposites that couple two nano-components together in the form of Core/Shell, nanoalloys, and doped nanostructures. Hybrid nanostructure provides another opportunity for tuning the physical and chemical properties at the nanoscale. This opens the door for the discovery of new properties and potential for more applications. This chapter is devoted to present, and discuss the recent advances and progress relevance for Plasmonic hybrid nanocomposites. In addition, literature reviewed on different attempts to obtain high quality plasmonic nanocomposites via chemical routes, and their physico-chemical aspects for this class of novel nanomaterials. The authors presented their recent published work regarding Plasmonic hybrid nanostructure regarding plasmonic-semiconductor, plasmonic magnetic and plasmonic graphene nanocomposites.

scholarly journals Effective Mechanical Properties and Thickness Determination of Boron Nitride Nanosheets Using Molecular Dynamics Simulation

Nanomaterials ◽  
2018 ◽  
Vol 8 (7) ◽  
pp. 546 ◽  
Author(s):  
Venkatesh Vijayaraghavan ◽  
Liangchi Zhang
Keyword(s):  
Mechanical Properties ◽  
Boron Nitride ◽  
Chemical Properties ◽  
Dynamics Simulation ◽  
Boron Nitride Nanosheets ◽  
Wide Scatter ◽  
Physical And Chemical ◽  
Effective Mechanical Properties ◽  
And Chemical Properties

Research in boron nitride nanosheets (BNNS) has evoked significant interest in the field of nano-electronics, nanoelectromechanical (NEMS) devices, and nanocomposites due to its excellent physical and chemical properties. Despite this, there has been no reliable data on the effective mechanical properties of BNNS, with the literature reporting a wide scatter of strength data for the same material. To address this challenge, this article presents a comprehensive analysis on the effect of vital factors which can result in variations of the effective mechanical properties of BNNS. Additionally, the article also presents the computation of the correct wall thickness of BNNS from elastic theory equations, which is an important descriptor for any research to determine the mechanical properties of BNNS. It was predicted that the correct thickness of BNNS should be 0.106 nm and the effective Young’s modulus to be 2.75 TPa. It is anticipated that the findings from this study could provide valuable insights on the true mechanical properties of BNNS that could assist in the design and development of efficient BN-based NEMS devices, nanosensors, and nanocomposites.

scholarly journals Concentration dependence of vibrational properties of bioprotectant/water mixtures by inelastic neutron scattering

2006 ◽  
Vol 4 (12) ◽  
pp. 167-173 ◽  
Author(s):  
S Magazù ◽  
F Migliardo ◽  
A.J Ramirez-Cuesta
Keyword(s):  
Neutron Scattering ◽  
Inelastic Neutron Scattering ◽  
Inelastic Neutron ◽  
Biological Molecules ◽  
Chemical Mechanisms ◽  
Structure And Dynamics ◽  
Biophysical Processes ◽  
Bending Modes ◽  
Physical And Chemical ◽  
Vibrational Features

Neutron scattering has been demonstrated to be a powerful tool for characterizing the structure and dynamics of biological molecules and for investigating the physical and chemical mechanisms of biophysical processes. The aim of the present work is to investigate by inelastic neutron scattering (INS) the vibrational behaviour of a class of bioprotectant systems, such as homologous disaccharides, trehalose, maltose and sucrose, in water mixtures. INS measurements have been performed on trehalose/H 2 O, maltose/H 2 O and sucrose/H 2 O mixtures at very low temperature as a function of concentration by using the thermal original spectrometer with cylindrical analyzers (TOSCA) spectrometer at the ISIS Facility (DRAL, UK). The findings allow the analyses of the vibrational features of the INS spectra in order to study the effect of disaccharides on the H 2 O hydrogen-bonded tetrahedral network. The obtained neutron scattering findings point out that disaccharides, and in particular trehalose, have a destructuring effect on the water tetrahedral network, as emphasized by the analysis of the librational modes region from 50 to 130 meV energy transfer. On the other hand, the analysis of the bending modes region (130–225  meV) shows a locally ordered structure in the disaccharide/H 2 O mixtures. Finally, the observed experimental evidences are linked to the different bioprotective effectiveness of disaccharides as a function of concentration.

Applications of Ceramic Nanoparticles in Nanomedicine

2012 ◽  
Vol 706-709 ◽  
pp. 467-471 ◽  
Author(s):  
Gianni Ciofani ◽  
Serena Danti ◽  
Leonardo Ricotti ◽  
Delfo D’Alessandro ◽  
Stefania Moscato ◽  
...  
Keyword(s):  
Barium Titanate ◽  
Boron Nitride ◽  
Biomedical Applications ◽  
Piezoelectric Properties ◽  
Boron Nitride Nanotubes ◽  
Ceramic Nanoparticles ◽  
High Concentrations ◽  
Barium Titanate Nanoparticles ◽  
Physical And Chemical

This paper reports on two examples of biomedical applications of ceramic nanoparticles. Thanks to their physical and chemical inertia, barium titanate nanoparticles and boron nitride nanotubes have been proved to have an optimal in vitro biocompatibility, even at high concentrations. Barium titanate nanoparticles-doxorubicin composites are successfully internalized by cancer cells, and allow for a considerable enhancement of drug up-take. Conversely, boron nitride nanotubes are explored as “nanotransducers”, thanks to their excellent piezoelectric properties. These two examples encourage further investigations and applications in biology and medicine of ceramic nanomaterials, that exhibit interesting advantages respect to traditional materials.

scholarly journals High-velocity impact of a hybrid CBN nanotube

2020 ◽  
Author(s):  
Enzo Armani ◽  
Pedro A S Autreto
Keyword(s):  
Boron Nitride ◽  
High Velocity ◽  
Boron Nitride Nanotubes ◽  
Hybrid Nanostructures ◽  
Extreme Conditions ◽  
High Velocity Impact ◽  
Velocity Impact ◽  
Reactive Molecular Dynamics ◽  
Atomic Chains ◽  
Dynamics Simulations

Abstract Nanomaterials under extreme conditions can behave in a completely different manner. High-velocity impact, for example, can produce nanoribbons without any chemical approach via carbon or boron nitride nanotubes unzipping. Although hybrid nanostructures have been used to create stronger structures, few studies on these materials under extreme conditions have been employed. In this work, we studied, using fully atomistic reactive molecular dynamics simulations an experimentally synthesized hybrid nanotube (boron nitride and carbon nanotubes concentrically assembled) under the high-velocity impact. Our results show that the combination of elastic and brittle materials can produce different structures, such as nanoribbons and boron nitride atomic chains. These results can have a significant impact on the production of new nanostructures.

Shell-model calculations of the far-infrared optical properties of CsI

1977 ◽  
Vol 55 (3) ◽  
pp. 227-234 ◽  
Author(s):  
J. E. Eldridge ◽  
Roger Howard ◽  
P. R. Staal
Keyword(s):  
Optical Properties ◽  
Shell Model ◽  
Inelastic Neutron Scattering ◽  
Far Infrared ◽  
Inelastic Neutron ◽  
Dielectric Constants ◽  
Wave Number ◽  
Model Calculations ◽  
Resonance Wave ◽  
Infrared Optical Properties

The far-infrared optical properties of CsI, including the real and imaginary dielectric constants, absorption coefficient, refractive index, and reflectivity, have been calculated absolutely using shell-model lattice-dynamical data, fitted to dispersion curves measured by inelastic neutron scattering, as input to the calculations. The calculations were based on cubic anharmonicity only. The results show a marked improvement in the wave number position of certain structure in the optical properties over that previously obtained using deformation-dipole lattice-dynamical data. The agreement with experiment at 300, 77, 20, and 12 K is generally very good apart from the obvious need for quartic anharmonicity at higher temperatures, a discrepancy in the wave number shift applied to the resonance wave number, and a few details of structure predicted by the shell model and not observed experimentally.

Statistical criteria of stellar population types

1966 ◽  
Vol 24 ◽  
pp. 101-110
Author(s):  
W. Iwanowska
Keyword(s):  
Stellar Population ◽  
Chemical Properties ◽  
Spectrophotometric Study ◽  
Physical And Chemical Properties ◽  
Population Type ◽  
The Galaxy ◽  
Distribution Parameters ◽  
Physical And Chemical ◽  
Statistical Criteria ◽  
And Chemical Properties

In connection with the spectrophotometric study of population-type characteristics of various kinds of stars, a statistical analysis of kinematical and distribution parameters of the same stars is performed at the Toruń Observatory. This has a twofold purpose: first, to provide a practical guide in selecting stars for observing programmes, second, to contribute to the understanding of relations existing between the physical and chemical properties of stars and their kinematics and distribution in the Galaxy.

Biophysical Measurement of Molecular Weight of Foot-and-Mouth Disease RNA Fragments

1974 ◽  
Vol 32 ◽  
pp. 262-263
Author(s):  
Sydney S. Breese ◽  
Howard L. Bachrach
Keyword(s):  
Chemical Properties ◽  
Foot And Mouth Disease ◽  
Mouth Disease ◽  
Distilled Water ◽  
Bovine Plasma ◽  
Mouth Disease Virus ◽  
Foot And Mouth ◽  
Carbon Coated ◽  
Rna Fragments ◽  
Physical And Chemical

Continuing studies on the physical and chemical properties of foot-and-mouth disease virus (FMDV) have included electron microscopy of RNA strands released when highly purified virus (1) was dialyzed against demlneralized distilled water. The RNA strands were dried on formvar-carbon coated electron microscope screens pretreated with 0.1% bovine plasma albumin in distilled water. At this low salt concentration the RNA strands were extended and were stained with 1% phosphotungstic acid. Random dispersions of strands were recorded on electron micrographs, enlarged to 30,000 or 40,000 X and the lengths measured with a map-measuring wheel. Figure 1 is a typical micrograph and Fig. 2 shows the distributions of strand lengths for the three major types of FMDV (A119 of 6/9/72; C3-Rezende of 1/5/73; and O1-Brugge of 8/24/73.

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