bluuebunny/crossref_metadata_2025 huggingface dataset:
Synthesis and Characterization of ZnS:Mn2+ Nano-Particles for White-Light Emitting
Authors: Yue Li Qing , Zhang Fu Jun , Huang Jin Zhao , Wang Li Wei
Published: April 2020

The sol–gel method was used to obtain a kind of white-light emitting ZnS:Mn2+ nanoparticles capped by methacrylic acid with an average particle size of ∼7nm. The photoluminescence spectra, X-ray diffraction spectra, Fourier transform infrared reflection spectra
and ultraviolet absorption spectra were used to measure their optical properties and crystal structures. The ZnS:Mn2+ nanoparticles with 0.58 wt% Mn2+ concentration emitted white light when excited by 380 nm. The PL spectrum exhibits two emission peaks under irradiation:
one at 480 nm generated from the ZnS matrix, and one at 590 nm emitted by the doped Mn2+ ions. The nanoparticles will only emit white light with the optimum Mn2+ concentration (0.58 wt%). X-ray diffraction demonstrates the synthesized ZnS:Mn2+ nanoparticles
have zinc blend crystal structure, and the infrared patterns of the capped ZnS:Mn2+ nanoparticles and methacrylic acid are comparable, indicating that the methacrylic polymer has capped or modified ZnS:Mn2+ nanoparticles.
Behavior of TiO2 Thin Film in a Nanocapacitor
Authors: Jia Dongdong , Shaffer C. , Pickering S. , Goonewardene A. , Wang Xiao-Jun
Published: April 2020

Gold and platinum nanocapacitors have been fabricated using a magnetron sputtering technique. TiO2 is used as a dielectric material to separate the metal layers which act as the parallel plates for the capacitors. The thickness for metal films and TiO2 layer is
80 nm and 400 nm, respectively. Capacitance of the nanocapacitors has been measured and dielectric constant of TiO2 calculated. Both capacitance and dielectric constant are observed to have strong frequency dependence.
The Fluctuation of Radiative Lifetime of Dielectric Luminescent-Ion-Containing Nanoparticles RandomlyDistributed in Media
Authors: Lai Chang , Wang Da-Jun , Duan Chang-Kui , Xia Shang-Da
Published: April 2020

The radiative lifetime of an emitter (such as a luminescent ion) is affected not only by the properties of the emitter itself but also by the dielectric properties of the surrounding media. The fluctuation of the local electrical field caused by random distribution of polarized luminescent-ion-containing
nanoparticles in media leads to the fluctuation of radiative lifetime of luminescent ions. Lifetime fluctuation has been calculated analytically by considering this effect. The results show that the fluctuation of radiative lifetime is not negligible and can be shown and observed in future
experiments.
The Influence of Source Material Composition on Morphology and Optical Properties of ZnO Nanostructures
Authors: Zhang S. L. , Tam K. H. , Djurišić A. B. , Hsu Y. F.
Published: April 2020

We investigated the influence of the composition of the source materials on the morphology and optical properties of ZnO nanostructures. The source materials consisted of a mixture of ZnO and carbon, or ZnO, carbon, and another metal oxide (In2O3, MnO2,
or V2O5). The addition of a different metal oxide to the source materials is a commonly used method to achieve doping and/or alteration of the morphology of ZnO nanostructures. For each metal oxide additive, we investigated the influence of different forms of carbon (graphite,
carbon nanofibers, and single wall carbon nano-tubes). Obtained nanostructures were studied using scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray spectroscopy, selected area electron diffraction, and photoluminescence. The morphology and the optical
properties of the obtained nanostructures were strongly dependent on the source material composition. Possible reasons for observed differences are discussed.
Size-Induced Variations in Lattice Dimension, Photoluminescence, and Photocatalytic Activity of ZnO Nanorods
Authors: Qiu Xiaoqing , Li Liping , Fu Xianzhi , Li Guangshe
Published: April 2020

Highly crystalline ZnO nanorods with diameters ranging from 5 to 57 nm were prepared by a seed-mediated solution method. With a diameter reduction, the lattice volume of ZnO nanorods increased and c/a ratio decreased, in apparent contradiction to what was observed in spherical
ZnO nano-crystals. All ZnO nanorods showed a strong yellow emission without the UV or green emissions that had been observed for ZnO nanostructures prepared by other methods. For larger diameters, the yellow emission exhibited an abnormal red shift, which was associated with the lattice variations
in the nanoscale structure and the resulting band modifications. The size-induced band modifications were also confirmed by the photocatalytic activity of ZnO nanorods, which have an optimum diameter (approximately 30 nm) for the photodegradation of Rhodamine B dye solution.
Electroluminescence from Light-Emitting Diodes by Using Water-Dispersed ZnSe Nanocrystals and Polymer
Authors: Xiong Sha , Huang Shihua , Tang Aiwei , Teng Feng
Published: April 2020

Electroluminescence was obtained from an indium-tin-oxide/poly[2-methoxy-5-(2′-ethylhexyloxy)-1,4-phenylene vinylene] (MEH-PPV): ZnSe/2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP)/8-tris-hydroxyquinoline (Alq3)/LiF/Al structured device, in which ZnSe nanocrystals
were synthesized in aqueous solution by using mercapto-acetate acid as stabilizer. The mechanical, electrical, and optical properties of the device were established. The photoluminescence and electroluminescence spectra changed with the mass ratio of ZnSe to MEH-PPV in the composite. Comparison
between the absorption spectra and photoluminescence spectra of the ZnSe nanocrystals and the MEH-PPV thin film exhibited an effective energy transfer from ZnSe nanocrystals to MEH-PPV, which was one reason for the difference between the photoluminescence and electroluminescence spectra of
the MEH-PPV: ZnSe composite film. The recombination mechanism of ZnSe nanocrystals under photo excitation and electric injection was investigated with the help of a single layer device structure of indium-tin-oxide/ZnSe/LiF/Al.
Fabrication and Spectroscopic Broadening Properties for 1.5 μm Amplification of Er3+-Doped BaF2 Nanoparticles
Authors: Lian Hongzhou , Liu Jie , Ye Zeren , Shi Chunshan
Published: April 2020

We show the potential application of Er3+-doped BaF2 nanoparticles prepared from microemulsion technology for 1.5 μm amplification in telecommunication. Nanoparticles with different sizes of about 8, 10, and 20.5 nm were prepared. The XRD patterns showed
the excursion of diffraction peaks. When the particle size is smaller or the diffraction angle is larger, this kind of excursion will be more serious. The emission bands of Er3+ at 1.54 μm for the three particle sizes at were as follows: 8 nm particles – 145 nm,
10 nm particles – 124 nm, and 20.5 nm particles – 82 nm (full width at half maximum, FWHM), or 173, 153, 97 nm (Δλeff), respectively. In all the three cases, the emission spectra were flat from 1.53 to 1.56 μm.
Nanostructure Induced by Femtosecond Laser in Various OH-Contents Silicas
Authors: Qiu Jianbei
Published: April 2020

Synthetic fused silicas with different OH content were irradiated with an ultrashort pulse laser, and the induced nanostructures were investigated. Compared with the samples before laser irradiation, two absorption bands centered at 4.8 eV corresponding to the E′(αSi•)
center and at 5.8 eV corresponding to the non-bridging oxygen hole center (NBOHC, αSi—O•), were observed after laser irradiation in high-OH silicas. A photoluminescence band with photon energy of 1.9 eV was observed in the irradiated silicas under 4.8 eV light excitation.
Though no red photoluminescence was observed after irradiating the inside of the low OH-containing silica samples, a similar phenomenon occurred when the laser beam was focused near the surface of low-OH silicas. The induced structures relaxed after annealing at 400 °C. A possible model
for the generation of 1.9 eV photoluminescence induced by an ultrashort pulse laser in wet and dry silicas was proposed.
Effect of Nd-Doping on the Optical Properties of Yttrium Aluminum Garnet Nanopowders
Authors: Wang Lidan , Zhang Ligong , Fan Yi , Luo Jingsong , Zhang Peiping , An Linan
Published: April 2020

Nd-doped and Nd/Si-codoped yttrium aluminum garnet powders were synthesized via a solvothermal method using ethanol as the solvent. The photoluminescence spectra of the powders revealed that the intensity of the emission increased with Nd-doping concentration initially and then decreased
with further increase in Nd concentration. The powder containing 3.5 atm% Nd exhibited the highest light emission intensity. The fluorescence lifetime of the yttrium aluminum garnet powders was also measured as a function of Nd-doping concentration. The results were fitted with an empirical
equation.
Preparation and Characterization of Hollow Carbon Nanospheres Supported Metallic Catalysts by Using One-Step Pyrolysis Method
Authors: Ding Ya , Xia Xing-Hua
Published: April 2020

A versatile one-step pyrolysis method is successfully employed to fabricate hollow carbon nanospheres (HCNs, ca. 60 nm in diameter) supported with metallic nanoparticle catalyst. The resultant catalyst hybrid was characterized by using TEM, FTIR, TGA measurements. It is confirmed that,
as the carbon precursor and hollow core/shell structure template, hollow chitosan nanospheres provide the important adsorption sites for the metallic precursor. The one-step pyrolysis process at 750 °C under nitrogen atmosphere results in the simultaneous decomposition of the chitosan
nanospheres to HCNs and the adsorbed metal salt complex to metallic nanoparticles. It is found that metallic nanoparticles with an average diameter of ca. 4 nm highly dispersed in the carbon shell of HCNs, and no aggregation phenomenon occurs under the high deposition temperature. As a demonstration,
the HCNs-supported Pt catalyst for the electrochemical methanol oxidation was studied.
Molecular Interactions Alter Clay and Polymer Structure in Polymer Clay Nanocomposites
Authors: Sikdar Debashis , Katti Kalpana S. , Katti Dinesh R.
Published: April 2020

In this work, using photoacoustic Fourier transform infrared spectroscopy (FTIR) we have studied the structural distortion of clay crystal structure in organically modified montmorillonite (OMMT) and polymer clay nanocomposites (PCN). To study the effect of organic modifiers on the
distortion of crystal structure of clay, we have synthesized OMMTs and PCNs containing same polymer and clay but with three different organic modifiers (12-aminolauric acid, n-dodecylamine, and 1,12-diaminododecane), and conducted the FTIR study on these PCNs. Our previous molecular
dynamics (MD) study on these PCNs reveals that significant nonbonded interactions (van der Waals, electrostatic interactions) exist between the different constituents (polymer, organic modifier, and clay) of nanocomposites. Previous work based on X-ray diffraction (XRD) and differential scanning
calorimetry (DSC) on the same set of PCNs shows that crystallinity of polymer in PCNs have changed significantly in comparison to those in pristine polymer; and, the nonbonded interactions between different constituents of PCN are responsible for the change in crystal structure of polymer
in PCN. In this work to evaluate the structural distortion of crystal structure of clay in OMMTs and PCNs, the positions of bands corresponding to different modes of vibration of Si—O bonds are determined from the deconvolution of broad Si—O bands in OMMTs and PCNs obtained from
FTIR spectra. Intensity and area under the Si—O bands are indicative of orientation of clay crystal structures in OMMTs and PCNs. Significant changes in the Si—O bands are observed from each vibration mode in OMMTs and PCNs containing three different organic modifiers indicating
that organic modifiers influence the structural orientation of silica tetrahedra in OMMTs and PCNs. Deconvolution of Si—O bands in OMMTs indicate a band at ∼1200 cm−1 that is orientation-dependent Si—O band. The specific changes in intensity and area under
this band for OMMTs with three different organic modifiers further confirm the change in structural orientation of silica tetrahedra of OMMTs by organic modifiers. Thus, from our work it is evident that organic modifiers have significant influence on the structure of polymer and clay in PCNs.
It appears that in nanocomposites, in addition to strong interactions at interfaces between constituents, the structure of different phases (clay and polymer) of PCN are also altered, which does not occur in conventional composite materials. Thus, the mechanisms governing composite action
in nanocomposites are quite different from that of conventional macro composites.
Capillary Effect of Multi-Walled Carbon Nanotubes Suspension in Composite Processing
Authors: Fan Zhihang , Advani Suresh G.
Published: April 2020

Carbon nanotubes (CNTs) do have the potential to improve the interlaminar shear strength (ILSS) of composites if they can be successfully integrated into the matrix as it infuses into the fiber preform. The infusion under capillary action of Multi-Walled Carbon Nanotubes (MWNT)/Epoxy
suspension with tubes of length 0.3∼1 μm in glass fiber bundles containing pores of the order of 5 nm∼100 μm was investigated. The influence of parameters such as suspension concentration, viscosity, porous media architecture, surface tension and contact angle were
explored. It was found that filtering of the suspension is a major challenge for uniform infusion for concentrations beyond 0.5% MWNT by weight. This is even truer for fiber bundles that are compacted. Hence for successful manufacturing, new infusion techniques that rely on fabrics of high
permeability will have to be developed to fabricate such nanocomposites.
Preparation and Properties of Poly(N-vinylcarbazole) and MWCNT Nanocomposites
Authors: Maity Arjun , Biswas Mukul
Published: April 2020

N-vinylcarbazole (NVC) was polymerized in bulk through the interaction of multi-walled carbon nanotube (MWCNT) without any extraneous catalyst. A PNVC-MWCNT composite was isolated by MeOH precipitation of a polymerization system containing NVC and MWCNT at melting temperature
of the monomer. The inclusion of PNVC in the composite was endorsed by the FTIR study. TG analysis revealed the thermal stability trend as MWCNT > PNVC-MWCNT composite > PNVC. DTA showed two exothermic peaks at 427 °C and 607 °C in the PNVC-MWCNT composite. Transmission electron
microscopic analyses of MWCNT revealed presence of tubular MWCNT particles with diameters in nm range while the corresponding analysis for the composite showed the formation of spherical dark polymer particles encapsulating cylindrical MWCNT moieties with some ends of uncoated MWCNT tubes
(light shades) protruding out of the dark spherical particles. Scanning electron microscopic analysis revealed presence of tubular CNT particles entangled with the composite particles of irregular shapes and sizes. XRD analysis revealed no additional crystalline peaks for PNVC in the composite.
In contrast to PNVC homopolymer (10–12–10–16 S/cm), the dc conductivity values of the composite varied form 1.3 to 33 S/cm depending upon the weight ratio of MWCNT and PNVC in the composite. Current–voltage characteristics of the composite showed
a linear variation and conductivity–temperature studies revealed an increase in conductivity by 35% in the temperature range 150–220 °C.
Polyaniline/Layered Zirconium Phosphate Nanocomposites: Secondary-Like Doped Polyaniline Obtained by the Layer-by-Layer Technique
Authors: Izumi Celly M. S. , Constantino Vera R. L. , Temperini Marcia L. A.
Published: April 2020

In the present work, nanocomposites of polyaniline (PANI) and layered α-Zr(HPO4)2˙H2O (α-ZrP) were prepared using two different approaches: (i) the in situ aniline polymerization in the presence of the layered inorganic
material and (ii) the layer-by-layer (LBL) assembly using an aqueous solution of the polycation emeraldine salt (ES-PANI) and a dispersion of exfoliated negative slabs of α-ZrP. These materials were characterized spectroscopically using mainly resonance Raman scattering at four
exciting radiations and electronic absorption in the UV-VIS-NIR region. Structural and textural characterizations were carried out using powder X-ray diffraction (XRD) and scanning electron microscopy (SEM). The polymer obtained by the in situ aniline polymerization is located primarily
in the external surface of the inorganic material although aniline monomers were intercalated between α-ZrP interlayer regions before oxidative polymerization. Through resonance Raman spectroscopy, it was observed that the formed polymer has semiquinone units (ES-PANI) and also
azo bonds (—N=N—), showing that this method results in a polymer with a different structure from the usual “head-to-tail” ES-PANI. The LBL assembly of pre-formed ES-PANI and exfoliated α-ZrP particles produces homogeneous films with reproducible deposition
from layer to layer, up to 20 bilayers. Resonance Raman (λ0 = 632.8 nm) spectrum of PANI/ZrP LBL film shows an enhancement in the intensity of the polaronic band at 1333 cm–1 (νC—N˙+) and the decrease of the band intensity at
1485 cm–1 compared to bulk ES-PANI. Its UV-VIS-NIR spectrum presents an absorption tail in the NIR region assigned to delocalized free charge carrier. These spectroscopic features are characteristic of highly conductive secondary doped PANI suggesting that polymeric chains
in PANI/ZrP LBL film have a more extended conformation than in bulk ES-PANI.
Structure, Wettability and Thermal Degradation of New Fluoro-Oligomer Modified Nanoclays
Authors: Valsecchi R. , Viganò M. , Levi M. , Turri S.
Published: April 2020

Quaternary ammonium salts based on monofunctionalized Perfluoropolyether (PFPE) oligomers were synthesized and used for the cation exchange process of sodium Montmorillonite nanoclays. The new fluoromodified nanoclays were characterized through X-rays diffraction (XRD), Fourier transform
infrared spectroscopy (FTIR), termogravimetric analysis (TGA), differential scanning calorimetry (DSC), electronic microscopy (SEM-EDS), and contact angle measurements (CA). In particular XRD showed rather complex patterns (presence of higher order reflections) which allowed the calculation
of basal spacings, regularly increasing with the molecular weight of the fluorinated macrocation. Both IR and SEM confirmed the presence of fluorinated segments at clays interface, while TGA showed a limited thermal stability with an onset of degradation temperature which seems not dependent
on the molecular weight of the macrocation. CA measurements showed a peculiar behaviour, with evident dynamic hysteresis phenomena and surface tension components quite different from those of commercially available, organomodified clays.
Specific Interactions Induced Dispersion and Confinement of Multi-Walled Carbon Nanotubes in Co-continuous Polymer Blends
Authors: Bose Suryasarathi , Bhattacharyya Arup R. , Kodgire Pravin V. , Kulkarni Ajit R. , Misra Ashok
Published: April 2020

Multiwall carbon nanotubes (MWNT) were melt-mixed with 50/50 co-continuous blends of polyamide 6 (PA6) and acrylonitrile-butadiene-styrene (ABS). Blending sequence and moulding processes were found to have a strong impact on the conductivity of the blends with MWNT. Aggregated nature
of the tubes, migration during processing and skin-core morphology generated during mould cooling step were found to be crucial parameters affecting the electrical conductivity of the blends. We report here the role of a reactive modifier: sodium salt of 6-amino hexanoic acid (Na-AHA) aiding
in uniform dispersion of the MWNT in the 50/50 PA6/ABS blends and restricting the tubes utilizing specific interactions during melt-mixing in the PA6 phase in the blends. We further varied the MWNT to Na-AHA ratio from 1:1 to 1:15 to optimize the concentration of MWNT required in achieving
lower electrical percolation threshold in co-continuous PA6/ABS blends. The associated percolation threshold was observed at ∼0.5 wt% MWNT with high dielectric constant.
Influence of Functionalization of Multi-Walled Carbon Nanotubes on the Properties of Ethylene Vinyl Acetate Nanocomposites
Authors: George Jinu Jacob , Sengupta Rajatendu , Bhowmick Anil K.
Published: April 2020

Commercially available multiwalled carbon nanotubes (MWNT) were chemically modified by amine, acid and silane and their ethylene vinyl acetate (EVA) based nanocomposites were prepared. Unmodified and modified nanotubes were characterized by thermogravimetry, X-ray diffraction, Raman
spectroscopy, X-ray photoelectron spectroscopy and transmission electron microscopy. Early degradation of modified nanotubes from the thermogravimetry study proved the presence of functional groups on nanotube surface. Increase in D-band to G-band ratio and a shift in radial breathing mode
peaks from the Raman spectra indicated the generation of surface defects due to functionalization and variation in van der Waals force of attraction between nanotube aggregates on modification. The unmodified nanotubes improved the tensile strength by 30% with 4 weight% of filler. Amine modification
imparted further increase in strength due to the presence of functional groups on the nanotube surface and the subsequent better dispersion of the nanotubes in the polymer matrix. The silane treatment imparted maximum improvement in various properties of the nanocomposites. The nanotubes provided
better thermal degradation stability and also higher thermal conductivity to virgin EVA. The results were well supported by the morphological as well as swelling study of the various samples.
Effect of ZnO Nanoparticles on the Structure and Ionic Relaxation of Poly(ethylene oxide)-LiI Polymer Electrolyte Nanocomposites
Authors: Bhattacharya S. , Ghosh A.
Published: April 2020

The effect of ZnO nanoparticles on the structure and ionic relaxation of LiI salt doped poly(ethylene oxide) (PEO) polymer electrolytes has been investigated. X-ray diffraction, high resolution transmission electron microscopy and field emission scanning electron microscopy show that
ZnO nanoparticles dispersed in the PEO-LiI polymer electrolyte reduce the crystallinity of PEO and increase relative smoothness of the surface morphology of the nanocomposite electrolyte. The electrical conductivity of the nanocomposites is found to increase due to incorporation of ZnO nanoparticles.
We have shown that the structural modification due to insertion of ZnO nanoparticles results in the enhancement of the mobility i.e., the hopping rate of mobile Li+ ions and hence the ionic conductivity of PEO-LiI-ZnO nanocomposite electrolyte.
Functionalised Hybrid Materials of Conducting Polymers with Individual Wool Fibers
Authors: Kelly Fern M. , Johnston James H. , Borrmann Thomas , Richardson Michael J.
Published: April 2020

Composites of natural protein materials, such as merino wool, with the conducting polymers polypyrrole (PPy) and polyaniline (PAn) have been successfully synthesised. In doing so, hybrid materials have been produced in which the mechanical strength and flexibility of the fibers is retained
whilst also incorporating the desired chemical and electrical properties of the polymer. Scanning electron microscopy shows PPy coatings to comprise individual polymer spheres, approximately 100 to 150 nm in diameter. The average size of the polymer spheres of PAn was observed to be approximately
50 to 100 nm in diameter. These spheres fuse together in a continuous sheet to coat the fibers in their entirety. The reduction of silver ions to silver metal nanoparticles onto the redox active polymer surface has also been successful and thus imparts anti-microbial properties to the hybrid
materials. This gives rise to further applications requiring the inhibition of microbial growth. The chemical and physical characterisation of such products has been undertaken through scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), electrical conductivity, cyclic
voltammetry, X-ray photoelectron spectroscopy (XPS) and the testing of their anti-microbial activity.
Mechanical and Electronic-Structure Properties of Compressed CdSe Tetrapod Nanocrystals
Authors: Schrier Joshua , Lee Byounghak , Wang Lin-Wang
Published: April 2020

The coupling of mechanical and optical properties in semiconductor nanostructures can potentially lead to new types of devices. This work describes our theoretical examination of the mechanical properties of CdSe tetrapods under directional forces, such as may be induced by AFM tips.
In addition to studying the general behavior of the mechanical properties under modifications of geometry, nanocrystal-substrate interaction, and dimensional scaling, our calculations indicate that mechanical deformations do not lead to large changes in the band-edge state eigenenergies, and
have only a weak effect on the oscillator strengths of the lowest energy transitions.
Tuning Morphology and Fluorescence of Aggregated Nanostructures of Derived Perylene Diimide Molecules
Authors: He Xiaorong , Zhou Weidong , Li Yuliang , Liu Xiaofeng , Li Cuihong , Liu Huibiao , Zhu Daoben
Published: April 2020

In this paper, we report on the self-assembly of water-soluble N,N′-di(N,N′-dimethyl-dodecane-1,12-diamide)-perylene-3,4,9,10-tetracarboxylic diimide (PDDoAM) in formic acid and chloride salts for producing varied nano-aggregates with different
optical properties. Interestingly, the self-assembly can lead to nanocubic, microsheet and “tower-like” nanostructures respectively, as demonstrated by Scanning Electron Microscopy (SEM) images. The optical properties of molecular aggregates were investigated by means of Confocal
Raman Microscopy, indicating the morphologies and fluorescence of these nanomaterials are dependent on acids, acid concentrations and casting methods.
Stability and Physicochemical Principles for Icosahedral Ti12X (X = Li to Xe) Clusters: A DFT Study
Authors: Salazar-Villanueva M. , Hernandez Tejeda P. H. , Rivas-Silva J. F. , Ascencio J. A.
Published: April 2020

Results about stability, electronic structure and characteristic electronic properties are reported for cluster structures based on icosahedra structure with a composition of Ti12X (X = Li to Xe) within the generalized gradient approximation of the density functional theory.
It is demonstrated that several elements allow an improvement on the stability of Ti13 by a doping process where the central atoms is substituted. C, Si, P, Co, Ge, Ru and Te lead to the largest gain in energy, while the HOMO-LUMO maximum gap distinguishes to just C, Si, P and Te
as the most probable to be found in experimental samples. The analysis included physicochemical study of the most stable clusters to predict chemical affinity and new properties. Results reported here are in agreement with partial studies of Ti12X but because of the considered elements,
a new scope is open of possible application mainly in the fields as sensors, catalysis and medicine, where the chemical selectivity is an important parameter.
Nanotribological Investigation of Magnetic Rigid Disks Lubricated with Perfluoropolyether Lubricant Under Varying Conditions
Authors: Liu E. , Tan K. S. , Tan H. I.
Published: April 2020

This paper studies the nanotribological behavior of magnetic rigid disks dip-coated with ultra thin perfluoropolyether (PFPE) Z-Dol 4000 lubricant layers up to 4 nm thick prior to or after exposure to ultraviolet (UV) light irradiation. Lube bonding ratios (LBRs) of 43–91% were
achieved by varying the UV irradiation time. The nanotribological and mechanical properties of the disks were measured with a nanotribometer under varying loading conditions. The effect of the LBR on the nanotribological behavior of the disks was also elucidated. We found that the lubricated
disks after UV treatment performed better compared to the lubricated disks without UV treatment. The experimental results indicated that the LBR of about 50% could achieve the best contact-start–stop and flyability performances.
Magnetic Vortex State Stability, Reversal and Dynamics in Restricted Geometries
Authors: Guslienko K. Yu.
Published: April 2020

Magnetic vortices are typically the ground states in geometrically confined ferromagnets with small magnetocrystalline anisotropy. In this article I review static and dynamic properties of the magnetic vortex state in small particles with nanoscale thickness and sub-micron and micron
lateral sizes (magnetic dots). Magnetic dots made of soft magnetic material shaped as flat circular and elliptic cylinders are considered. Such mesoscopic dots undergo magnetization reversal through successive nucleation, displacement and annihilation of magnetic vortices. The reversal process
depends on the stability of different possible zero-field magnetization configurations with respect to the dot geometrical parameters and application of an external magnetic field. The interdot magnetostatic interaction plays an important role in magnetization reversal for dot arrays with
a small dot-to-dot distance, leading to decreases in the vortex nucleation and annihilation fields. Magnetic vortices reveal rich, non-trivial dynamical properties due to existance of the vortex core bearing topological charges. The vortex ground state magnetization distribution leads to a
considerable modification of the nature of spin excitations in comparison to those in the uniformly magnetized state. A magnetic vortex confined in a magnetically soft ferromagnet with micron-sized lateral dimensions possesses a characteristic dynamic excitation known as a translational mode
that corresponds to spiral-like precession of the vortex core around its equilibrium position. The translation motions of coupled vortices are considered. There are, above the vortex translation mode eigenfrequencies, several dynamic magnetization eigenmodes localized outside the vortex core
whose frequencies are determined principally by dynamic demagnetizing fields appearing due to restricted dot geometry. The vortex excitation modes are classified as translation modes and radially or azimuthally symmetric spin waves over the vortex ground state. Studying the spin eigenmodes
in such systems provides valuable information to relate the particle dynamical response to geometrical parameters. Unresolved problems are identified to attract attention of researchers working in the area of nanomagnetism.
The Effect of Mn and B on the Magnetic and Structural Properties of Nanostructured Fe60Al40 Alloys Produced by Mechanical Alloying
Authors: Rico M. M. , Alcázar Pérez G. A. , Zamora L. E. , González C. , Greneche J. M.
Published: April 2020

The effect of Mn and B on the magnetic and structural properties of nanostructured samples of the Fe60Al40 system, prepared by mechanical alloying, was studied by 57Fe Mössbauer spectrometry, X-ray diffraction and magnetic measurements. In the case
of the Fe60–xMnxAl40 system, 24 h milling time is required to achieve the BCC ternary phase. Different magnetic structures are observed according to the temperature and the Mn content for alloys milled during 48 h: ferromagnetic, anti-ferromagnetic,
spin-glass, reentrant spin-glass and superparamagnetic behavior. They result from the bond randomness behaviour induced by the atomic disorder introduced by the MA process and from the competitive interactions of the Fe–Fe ferromagnetic interactions and the Mn–Mn and Fe–Mn
antiferromagnetic interactions and finally the presence of Al atoms acting as dilutors. When B is added in the Fe60Al40 alloy and milled for 12 and 24 hours, two crystalline phases were found: a prevailing FeAl BCC phase and a Fe2B phase type. In addition,
one observes an additional contribution attributed to grain boundaries which increases when both milling time and boron composition increase. Finally Mn and B were added to samples of the Fe60Al40 system prepared by mechanical alloying during 12 and 24 hours. Mn content
was fixed to 10 at.% and B content varied between 0 and 20 at.%, substituting Al. X-ray patterns show two crystalline phases, the ternary FeMnAl BCC phase, and a (Fe,Mn)2B phase type. The relative proportion of the last phase increases when the B content increases, in addition to
changes of the grain size and the lattice parameter. Such behavior was observed for both milling periods. On the other hand, the magnetic hyperfine field distributions show that both phases exhibit chemical disorder, and that the contribution attributed to the grain boundaries is less important
when the B content increases. Coercive field values of about 102 Oe slightly increase with boron content. Comparison with previous results on FeAlB alloys shows that Mn promotes the structural stability of the nanostructured powders.
Planar Spin-Transfer Device with a Dynamic Polarizer
Authors: Bazaliy Ya. B. , Olaosebikan D. , Jones B. A.
Published: April 2020

In planar nano-magnetic devices magnetization direction is kept close to a given plane by the large easy-plane magnetic anisotropy, for example by the shape anisotropy in a thin film. In this case magnetization shows effectively in-plane dynamics with only one angle required for its
description. Moreover, the motion can become overdamped even for small values of Gilbert damping. We derive the equations of effective in-plane dynamics in the presence of spin-transfer torques. The simplifications achieved in the overdamped regime allow to study systems with several dynamic
magnetic pieces ("free layers"). A transition from a spin-transfer device with a static polarizer to a device with two equivalent magnets is observed. When the size difference between the magnets is less than critical, the device does not exhibit switching, but goes directly into the "windmill"
precession state.
Magnetization Configurations and Magnetization Reversal of Thin Submicron Permalloy Ellipses with Structural Defects
Authors: Chang Ching-Ray , Yang Jyh-Shinn
Published: April 2020

We have studied the magnetic switching behavior of thin elliptical permalloy films with structural defects by micromagnetic simulations. The nonmagnetic void was found to tend to pin the adjacent magnetic moment, which alters the local equilibrium magnetization patterns and modifies
the switching behavior of magnetization. In particular, for the case of voids close to the edge, the curling effect of voids is significant, and induces the occurrence of the multiple-stage modes of magnetization reversal, resulting in a high switching field.
Magnetic Properties of Nickel and Cobalt Catalysts Supported on Nanoporous Oxides
Authors: Gómez-Polo C. , Gil A. , Korili S. A. , Pérez-Landazabal J. I. , Recarte V. , Trujillano R. , Vicente M. A.
Published: April 2020

The aim of this work is to use magnetic measurements as a research tool in the study of possible metal-support interactions in nickel and cobalt nanoporous catalysts. Several physicochemical techniques, namely nitrogen adsorption, X-ray diffraction, temperature-programmed reduction
and chemical analysis, were used to analyze the role of the preparation method and the nature of the support on the existence of such metal-support interactions and to relate them with the magnetic response of these nanoporous systems. The catalysts were prepared by incipient wetness impregnation
and precipitation-deposition with two commercial oxides, γ-Al2O3 and SiO2, as supports. The magnetic behavior of the catalysts is drastically affected by the existence of interactions between the metal and the support during the preparation procedure.
The samples with weak metal-support interactions have characteristic magnetic behavior of antiferromagnetic metal oxide nanoparticles, while the ones having strong interactions display spin-glass like behavior.
Structural and Magnetic Behaviour of Soft Magnetic Finemet-Type Ribbons
Authors: Iturriza N. , Fernández L. , Chizhik A. , Vara G. , Pierna A. R. , Val del J. J.
Published: April 2020

Different kinds of magnetic anisotropies have been induced during the nanocrystallization process of Co- and Ni-rich amorphous ferromagnetic (Finemet) ribbons by the application of a constant stress or an axial magnetic field during the annealing process. Magnetization measurements
have evidenced the presence od macroscopic anisotropy in the treated samples. The main goal of this work has been, after a careful DSC study, the structural analysis of the treated ribbons using X-ray Diffraction and Atomic Force Microscopy (AFM), detecting substantial differences in the crystallization
state and grain size of the samples depending on the thermal treatment that was carried out. Moreover, AFM measurements revealed in all the treated samples a strong nanocrystallisation of the surface without evidences of amorphous matrix, which contrast with XRD measurements that have shown
a high content of amorphous phase in the bulk of the ribbons. Magneto-optical Kerr effect measurements have been performed with the aim to elucidate the complex magnetic behaviour that is expected for the surface of the ribbons, measuring surface hysteresis loops that showed much higher coercive
field values than that obtained in the bulk material.
Quasicontinuum-Like Reduction of Density Functional Theory Calculations of Nanostructures
Authors: Negrut Dan , Anitescu Mihai , El-Azab Anter , Zapol Peter
Published: April 2020

Density functional theory can accurately predict chemical and mechanical properties of nanostructures, although at a high computational cost. A quasicontinuum-like framework is proposed to substantially increase the size of the nanostructures accessible to simulation. It takes advantage
of the near periodicity of the atomic positions in some regions of nanocrystalline materials to establish an interpolation scheme for the electronic density in the system. The electronic problem embeds interpolation and coupled cross-domain optimization techniques through a process called
electronic reconstruction. For the optimization of nuclei positions, computational gains result from explicit consideration of a reduced number of representative nuclei and interpolating the positions of the rest of nuclei following the quasicontinuum paradigm. Numerical tests using the Thomas-Fermi-Dirac
functional demonstrate the validity of the proposed framework within the orbital-free density functional theory.
High-Temperature Stability of Silicon Carbide Nanowires
Authors: Shim Hyun Woo , Kuppers Jaron D. , Huang Hanchen
Published: April 2020

The paper reports morphology and structure transitions of silicon carbide (SiC) nanowires during high temperature annealing; the as-prepared nanowires are in the form of SiC core and SiO2 shell. The transition temperature is about 1200 °C, 600 °C lower than that of
SiC microfibers, and it starts with the formation of junctions of individual nanowires. The junctions grow into webs while the crystalline SiC cores of the nanowires oxidize. The growth and the oxidation eventually lead to the formation of an oxide film, when the transition completes. The
thermal stability and the transition mechanisms of SiC nanowires are critical to their applications in high temperature environments.
In Situ Synthesis and Characterization of Multi-walled Carbon Nanotube/Prussian Blue Nanocomposite Materials and Application
Authors: Qiu Jian-Ding , Xiong Meng , Liang Ru-Ping , Zhang Jia , Xia Xing-Hua
Published: April 2020

An effective and facile in situ electroless deposition approach for the fabrication of multi-walled carbon nanotube-supported Prussian blue nanoparticle (MWNTs/PB NP) composite nanomaterials is demonstrated in this article. The coverage of PB NPs on MWNTs is tunable by varying
the experimental parameters, such as the initial molar concentration of FeCl3 + K3[Fe(CN)6], the relative concentration of FeCl3 + K3[Fe(CN)6] to MWNTs, and the temperature and duration of the heat treatment. This method involves
a simple mixing process followed by a mild heating process and does not need the exhaustive surface oxidation process of MWNTs. TEM, FTIR, UV, and XRD are all used to characterize the MWNTs/PB composite materials. In addition, the electrochemical behavior of PB and catalysis of the reduction
of H2O2 are investigated. The novel method is expected to be applicable for preparation of other coordination polymer/MWNTs composites and finds use in applications for electronic nanodevices.
Scanning Probe Oxidation Lithography on Ta Thin Films
Authors: Okur Salih , Büyükköse Serkan , Tari Suleyman
Published: April 2020

A Semi-Contact Scanning Probe Lithography Technique (SC-SPL) has been applied to create nano-oxide patterns on Ta thin films grown by DC magnetron sputtering method on SiO2/Si substrates. The height and linewidth profiles of nano-oxide lines created by a conductive AFM tip
on Ta film surfaces were measured as a function of applied voltage, oxidation time, humidity, and tip apex curvature. The AFM surface measurements show that the height of the oxides increases linearly with increasing voltage; but there was no oxide growth, when less than 4 V was applied even
at 85% relative humidity. Electrical measurements were performed and the resistivities of the TaOx layer and Ta film were obtained as 5.76 × 108 and 1.4 × 10−5 Ohm-cm, respectively.
pH Controlled Synthesis of High Aspect-Ratio Gold Nanorods
Authors: Wei Qingshan , Ji Jian , Shen Jiacong
Published: April 2020

Here we report the two-step synthesis of high aspect-ratio gold nanorods via combining low pH growth and higher cetyltrimethylammonium bromide concentration. The approach is motivated by the "slow growth principle," which has been demonstrated recently as a effective protocol to prepare
high aspect-ratio one-dimensional nanostructures. When the pH value of the growth solution gradually decreased, the growth rate of nanorods was significantly decreased and a continuous morphological changing from uniform monodisperse gold nanospheres to extraordinary long gold nanorods occured.
By simultaneously decreasing the growth pH and increasing the concentration of cetyltrimethylammonium bromide, the length of gold nanorods could be further elongated to above 2 μm with large aspect-ratio of above 80. This kind of high aspect-ratio gold nanorods could be excellent
building blocks for optical or electrical nanodevices in future.
A Simple Method for the Prevention of Non-Specific Adsorption by Nanocrystals onto Surfaces
Authors: Fernandez Carlos A. , Wiacek Robert J. , Nachimuthu Ponnusamy , Fryxell Glen E. , Pierson Amanda M. , Warner Cynthia L. , Warner Marvin G. , Addleman R. Shane
Published: April 2020

In this work we introduce an efficient method for averting non-specific adsorption of various nanoparticles to typical oxide surfaces, such as glass, quartz, and sapphire, through the attachment of a fluorinated self-assembled monolayer (SAM) that minimizes the interactions between
stabilized nanoparticles and these surfaces. This surface treatment is shown to be effective for a variety of nanoparticles in a range of solvent systems. As a result, monitoring and characterization of nanoparticles and their surface chemistry is allowed, while simultaneously preventing loss
of expensive nanomaterials to the various surfaces inherent in laboratory apparatus.
Evaluation of the Binding Properties of Maghemite Nanoparticle Surface-Coated with Meso-2-3-Dimercaptosuccinic Acid to Serum Albumin
Authors: Simoni Andreza R. , Garcia Mônica P. , Azevedo Ricardo B. , Chaves Sacha Braun , Lacava Z. G. M. , Lima E. C. D. , Morais P. C. , Tedesco A. C.
Published: April 2020

In this study the interaction between magnetic nanoparticles (MNPs) surface-coated with meso-2,3-dimercaptosuccinic acid (DMSA) with both bovine serum albumin (BSA) and human serum albumin (HSA) was investigated. The binding of the MNP-DMSA was probed by the fluorescence quenching of
the BSA and HSA tryptophan residue. Magnetic resonance and light microscopy analyses were carried out in in vivo tests using female Swiss mice. The binding constants (Kb) and the complex stoichiometries (n) indicate that MNP-DMSA/BSA and MNP-DMSA/HSA complexes
have low association profiles. After five minutes following intravenous injection of MNP-DMSA into mice's blood stream we found the lung firstly target by the MNP-DMSA, followed by the liver in a latter stage. This finding suggests that the nanoparticle's DMSA-coating process probably hides
the thiol group, through which albumin usually binds. This indicates that biocompatible MNP-DMSA is a very promising material system to be used as a drug delivery system (DDS), primarily for lung cancer treatment.
Size Tunablity of CdTe Crystallites in Dendrimer Nanocomposites and Temperature Dependent Focusing of Size Distribution
Authors: Ghosh Srabanti , Priyam Amiya , Chatterjee Anindita , Saha Abhijit
Published: April 2020

CdTe/Dendrimer nanocomposites have been synthesized for the first time in aqueous and non-aqueous media using PAMAM dendrimer (Generation 5.0). The average size of the as-prepared nanocomposites, as determined from dynamic light scattering (DLS) measurements, was found to be typically
182 nm and 23 nm in water and methanol, respectively under identical conditions of temperature (5 °C) and reagent ratio (Cd2+:Te2−, 1:0.5). The size of CdTe NPs within the nanocomposites, was found to be 3.1 and 2.8 nm for the aforementioned samples determined
from optical absorption spectra using tight binding approximation. The NPs possess good degree of cystallinity as discernible from the lattice fringes in high-resolution transmission electron microscopic (HRTEM). Transmission electron microscopic (TEM) image and the cubic crystal phase was
ascertained from the small area electron diffraction (SAED) pattern. Analysis of FTIR data suggests that CdTe NPs are bound to the surface amine groups as well as –NHCO– moieties lying in the interior of dendrimer structure. The present work demonstrates how the quality of the
CdTe NPs formed within the dendrimer matrix can be nicely tuned by varying the parameters, namely, temperature, molar ratio of Cd2+:Te2− and pH. Changing of Cd2+:Te2− ratio of 1:1 to 1:0.5, decreased the average particle size from 5.0
nm to 3.4 nm with concomitant narrowing of size distribution by ∼35% at 10 °C. On lowering down the synthesis temperature (25 °C→5 °C), the average particle size remained unaffected while the size distribution became sharply focused. However, the extent of focusing was
found to be more in methanol (40%) than that in water (30%).
Nanostructures of Crystalline Molybdenum Trioxide Grown by Condensation in a Carrier Gas
Authors: Diaz-Droguett D. E. , Fuenzalida V. M. , Solorzano G.
Published: April 2020

Molybdenum trioxide nanostructures were grown by direct evaporation of MoO3 from a tungsten boat resistively heated in the presence of hydrogen or helium as carrier gas at pressures from 100 to 600 Pa. Crystalline structures such as, nanoribbons, nanofibers, nanoneedles and
nanoparticles were obtained at source temperatures below 900 °C. On the other hand, at source temperatures above 1000 °C, nanoporous structures were obtained. The latter were found more often when hydrogen was used as carrier gas.