Search results for "electron microscopy"

showing 10 items of 706 documents

In Situ Heating TEM Study of Onion-like WS2 and MoS2 Nanostructures Obtained via MOCVD

2007

We report on the in situ heating transmission electron microscopy (TEM) study of WS2 and MoS2 nanoparticles obtained from metal–organic chemical vapor deposition (MOCVD). The general behavior of MoS2 and WS2 is similar: Round, amorphous particles in the pristine sample transform to hollow, onion-like particles upon annealing. A second type of particle with straight layers exhibits only minor changes. A significant difference between both compounds could be demonstrated in their crystallization behavior. The results of the in situ heating experiments are compared to those obtained from an ex situ annealing process under Ar.

Materials scienceNanostructureAnnealing (metallurgy)General Chemical EngineeringNanoparticleNanotechnologyGeneral ChemistryChemical vapor depositionAmorphous solidlaw.inventionChemical engineeringTransmission electron microscopylawMaterials ChemistryMetalorganic vapour phase epitaxyCrystallizationChemistry of Materials
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Synthesis and characterization of ZnO/ZnS/MoS2 core-shell nanowires

2017

The present research was supported by the Latvian National Research Program IMIS2 . Authors are grateful for Dr. Robert Kalendarev and Martins Zubkins for assistance in magnetron sputtering, Dr. Krisjanis Smits for TEM measurements, Dr. Roberts Zabels for AFM measurements and Reinis Ignatans for XRD measurements.

Materials scienceNanostructureAnnealing (metallurgy)NanowireNanotechnology02 engineering and technology010402 general chemistry01 natural sciencesChemical reactionInorganic Chemistry:NATURAL SCIENCES:Physics [Research Subject Categories]A1 CharacterizationMaterials ChemistryWaferAmmonium molybdateB1 Zinc compounds021001 nanoscience & nanotechnologyCondensed Matter PhysicsB1 Oxides0104 chemical sciencesA1 Crystal morphologyB1 SulfidesA1 NanostructuresChemical engineeringTransmission electron microscopySelected area diffraction0210 nano-technologyJournal of Crystal Growth
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Morphological evolution of InAs/InP quantum wires through aberration-corrected scanning transmission electron microscopy

2010

Evolution of the size, shape and composition of self-assembled InAs/InP quantum wires through the Stranski–Krastanov transition has been determined by aberration-corrected Z-contrast imaging. High resolution compositional maps of the wires in the initial, intermediate and final formation stages are presented. (001) is the main facet at their very initial stage of formation, which is gradually reduced in favour of {114} or {118}, ending with the formation of mature quantum wires with {114} facets. Significant changes in wire dimensions are measured when varying slightly the amount of InAs deposited. These results are used as input parameters to build three-dimensional models that allow calcu…

Materials scienceNanostructureCondensed matter physicsMechanical EngineeringQuantum wireThin filmsQuantum wiresElastic energyBioengineeringGeneral ChemistryCondensed Matter::Mesoscopic Systems and Quantum Hall EffectStrain energyCondensed Matter::Materials ScienceMechanics of MaterialsTransmission electron microscopyScanning transmission electron microscopyGeneral Materials ScienceElectrical and Electronic EngineeringThin filmTransmission electron microscopyWetting layer
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Spatial carrier distribution in InP/GaAs type II quantum dots and quantum posts

2011

We performed a detailed investigation of the structural and optical properties of multi-layers of InP/GaAs quantum dots, which present a type II interface arrangement. Transmission electronic microscopy analysis has revealed relatively large dots that coalesce forming so-called quantum posts when the GaAs layer between the InP layers is thin. We observed that the structural properties and morphology affect the resulting radiative lifetime of the carriers in our systems. The carrier lifetimes are relatively long, as expected for type II systems, as compared to those observed for single layer InP/GaAs quantum dots. The interface intermixing effect has been pointed out as a limiting factor for…

Materials scienceNanostructureCondensed matter physicsbusiness.industryMechanical EngineeringBioengineeringGeneral ChemistryElectronFermionCarrier lifetimeCondensed Matter::Mesoscopic Systems and Quantum Hall EffectCondensed Matter::Materials ScienceMechanics of MaterialsQuantum dotTransmission electron microscopyOptoelectronicsGeneral Materials ScienceElectrical and Electronic EngineeringWave functionbusinessQuantumNanotechnology
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Fast-Response Single-Nanowire Photodetector Based on ZnO/WS 2 Core/Shell Heterostructures

2018

This work was supported by the Latvian National Research Program IMIS2 and ISSP project for Students and Young Researchers Nr. SJZ/2016/6. S.P. is grateful to the ERA.Net RUS Plus WATERSPLIT project no. 237 for the financial support. S.V. is grateful for partial support by the Estonian Science Foundation grant PUT1689.

Materials scienceNanostructureScanning electron microscopeNanowirePhotodetector02 engineering and technology010402 general chemistry01 natural sciences7. Clean energysymbols.namesake:NATURAL SCIENCES:Physics [Research Subject Categories]General Materials Sciencecore/shell nanowirestransitional metal chalcogenidesvan der Waals epitaxybusiness.industryHeterojunction021001 nanoscience & nanotechnology0104 chemical sciencesTransmission electron microscopy1D/1D heterostructuressymbolsphotodetectorsOptoelectronicsCharge carrier0210 nano-technologybusinessRaman spectroscopyACS Applied Materials & Interfaces
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Flash microwave synthesis of trevorite nanoparticles.

2008

Nickel ferrite nanoparticles have several possible applications as cathode materials for rechargeable batteries, named 'lithium-ion' batteries. In this study, NiFe{sub 2}O{sub 4} was prepared by microwave induced thermohydrolysis. The obtained nanoparticles were characterized by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), BET method, transmission electron microscopy (TEM) and small angle X-ray scattering (SAXS). All the results show that the microwave one-step flash synthesis leads in a very short time to NiFe{sub 2}O{sub 4} nanoparticles with elementary particles size close to 4-5 nm, and high specific surfaces (close to 240 m…

Materials scienceNanostructureScanning electron microscopeXRDAnalytical chemistryNanoparticle02 engineering and technology010402 general chemistry01 natural sciences7. Clean energyNanomaterialsInorganic ChemistryMaterials ChemistryIron oxideFerritesPhysical and Theoretical ChemistryNickel oxideX-ray spectroscopySmall angle X ray scatteringParticle sizeDispersive spectrometryLithium batteryNanostructured materials021001 nanoscience & nanotechnologyCondensed Matter Physics0104 chemical sciencesElectronic Optical and Magnetic MaterialsElectrode materialMicrowave heatingOrganic conductorsX-ray crystallographyCeramics and CompositesFerrite (magnet)NanoparticlesNiFe2O40210 nano-technologyScanning electron microscopyMicrowaveTransmission electron microscopyNanomaterial synthesis
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Physico-chemical characterization of Pd nanoparticles synthesized in w/o microemulsions

1998

Abstract The long time stability of surfactant-coated Pd nanoparticles in w/o microemulsions has been investigated. It has been proven that in suitable conditions, the use of the functionalized surfactant Pd(AOT)2 allows to obtain very stable nanosized Pd particles and to finely control their average size.

Materials scienceNanostructureSmall-angle X-ray scatteringBioengineeringNanotechnologyCharacterization (materials science)BiomaterialsChemical engineeringPulmonary surfactantMechanics of MaterialsTransmission electron microscopyPd nanoparticlesParticleMicroemulsionMaterials Science and Engineering: C
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The structural properties of GaN/AlN core-shell nanocolumn heterostructures.

2010

International audience; The growth and structural properties of GaN/AlN core-shell nanowire heterostructures have been studied using a combination of resonant x-ray diffraction, Raman spectroscopy and high resolution transmission electron microscopy experiments. For a GaN core of 20 nm diameter on average surrounded by a homogeneous AlN shell, the built-in strain in GaN is found to agree with theoretical calculations performed using a valence force field model. It is then concluded that for an AlN thickness up to at least 12 nm both core and shell are in elastic equilibrium. However, in the case of an inhomogeneous growth of the AlN shell caused by the presence of steps on the sides of the …

Materials scienceNanowireShell (structure)Bioengineering02 engineering and technology01 natural sciencessymbols.namesake0103 physical sciencesGeneral Materials ScienceElectrical and Electronic EngineeringHigh-resolution transmission electron microscopy010302 applied physicsCondensed matter physicsbusiness.industryMechanical EngineeringHeterojunctionGeneral Chemistry[CHIM.MATE]Chemical Sciences/Material chemistry021001 nanoscience & nanotechnologyCrystallographic defectCore (optical fiber)Mechanics of MaterialsTransmission electron microscopysymbolsOptoelectronics0210 nano-technologyRaman spectroscopybusinessNanotechnology
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Structural and Optical Properties of Novel Surfactant Coated TiO2–Ag Based Nanoparticles

2010

Stable dispersions of surfactant-coated TiO2–Ag based nanoparticles in apolar medium have been prepared by performing sequentially the hydrolysis of titanium(IV) isopropoxide and the reduction of Ag? in the confined space of sodium bis(2-ethylhexyl)sulfosuccinate (NaAOT) reverse micelles. Depending on the sequence length, this novel procedure allowed the synthesis of semiconductor–metal nanoparticles, nominally indicated as TiO2/Ag, TiO2/Ag/TiO2, and TiO2/Ag/TiO2/ Ag, stabilized by a monolayer of oriented surfactant molecules. The structural characterization of these nanoparticles has been performed by High Resolution Transmission Electron Microscopy (HR-TEM), while optical properties were …

Materials scienceOptical propertiesAg@TiO2 nanostructures Optical properties Electron microscopyBand gapNanoparticleNanochemistryGeneral ChemistryAg-TiO2 nanostructuresCondensed Matter PhysicsBiochemistryAg-TiO2 nanostructures; Optical properties; Electron microscopyAmorphous solidCrystallographyMonolayerElectron microscopyGeneral Materials ScienceSurface plasmon resonanceAbsorption (chemistry)High-resolution transmission electron microscopySettore CHIM/02 - Chimica Fisica
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Subtractive imaging in confocal scanning microscopy using a CCD camera as a detector

2012

[EN] We report a scheme for the detector system of confocal microscopes in which the pinhole and a large-area detector are substituted by a CCD camera. The numerical integration of the intensities acquired by the active pixels emulates the signal passing through the pinhole. We demonstrate the imaging capability and the optical sectioning of the system. Subtractive-imaging confocal microscopy can be implemented in a simple manner, providing superresolution and improving optical sectioning. (C) 2012 Optical Society of America

Materials scienceOptical sectioningConfocalConfocal scanning microscopylaw.inventionOpticsConfocal microscopylawOnionsMicroscopyImage Processing Computer-AssistedMicroscopyMicroscopy Confocalbusiness.industryScanning microscopyScanning confocal electron microscopyEquipment DesignAtomic and Molecular Physics and OpticsConfocal microscopyFISICA APLICADASubtraction TechniqueLight sheet fluorescence microscopyPinhole (optics)businessAlgorithmsOptics Letters
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