Metallic Nanoparticles Embedded in a Dielectric Matrix: Growth Mechanisms and Percolation

We present a study of the preparation and structural characterization of granularAg-ZrO2,Co-ZrO2, andAu-ZrO2thin films grown by pulsed laser deposition (PLD) in a wide range of volume fractionxof metal (0.08<xAg<0.28,0.06<xCo<0.40, and0.08<xAu<0.55). High-resolution transmission electron microscopy (HRTEM) showed regular distribution of spherical Au, Co, and Au nanoparticles having very sharp interfaces with the amorphous matrix. The structural results are compared aiming to stress the effect of the actual microstructure on the percolation threshold. Two different mechanisms of particle growing as a function of the metal content are evidenced: nucleation and particle coalescence, with their relative significance depending strongly on the type of metal, giving rise to very different values of the percolation threshold (xc(Ag)∼0.28,xc(Co)∼0.35, andxc(Au)∼0.55).

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STRUCTURAL AND MORPHOLOGICAL CHARACTERIZATION OF GOLD NANOPARTICLES BY TEM AND DIGITAL CIS TECHNIQUE

International Journal of Nanoscience ◽

10.1142/s0219581x10007058 ◽

2010 ◽

Vol 09 (05) ◽

pp. 399-406 ◽

Cited By ~ 2

Author(s):

A. A. EL-DALY

Keyword(s):

Electron Microscopy ◽

Transmission Electron Microscopy ◽

Au Nanoparticles ◽

Morphological Characterization ◽

Particle Sizes ◽

Rigid Surface ◽

Gold Nanocrystals ◽

Driving Mechanisms ◽

Transmission Electron

In this paper, we report a convenient and informative procedure for detecting the morphology and surface structure of individual gold nanocrystals using digital Crystal Image Software (CIS) processing of transmission electron microscopy (TEM) image, which comprises coalescence phenomena of these nanoparticles. The results show that the internal structure of Au nanoparticles has a core of gold atoms arranged as a Marks decahedron, surrounded by additional gold–organic compound layers forming a rigid surface layer, and its outer layer comprises four staple motif bridge molecules that resemble handles, formed an unusual pattern. The obtained results improved our understanding of the basics of the coalescence phenomena such as the driving mechanisms acting at different particle sizes. However, these discrete natures of the nanoparticles will assist in the understanding of principles of nanocore assembly and opens a new window for nanoparticles chemistry.

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Growth and Characterization of Cobalt-filled Carbon Nanotubes Prepared by a Simple Catalytic Method

MRS Proceedings ◽

10.1557/proc-776-q8.17 ◽

2003 ◽

Vol 776 ◽

Author(s):

Xicheng Ma ◽

Yuanhua Cai ◽

Xia Li ◽

Ning Lun ◽

Shulin Wen

Keyword(s):

Carbon Nanotubes ◽

Metallic Nanoparticles ◽

Low Cost ◽

Catalytic Method ◽

Selected Area Electron Diffraction ◽

Transmission Electron ◽

High Resolution Tem ◽

One Step

AbstractHigh-quality cobalt-filled carbon nanotubes (CNTs) were prepared in situ in the decomposition of benzene over Co/silica-gel nano-scale catalysts. Unlike the previous reports, the catalysts needn't be pre-reduced prior to the forming of Co-filled CNTs, thus the advantage of this method is that Co-filled CNTs can be produced in one step, at a relatively low cost. Transmission electron microscopy (TEM) investigation showed that the products contained abundance of CNTs and most of them were filled with metallic nanoparticles or nanorods. High-resolution TEM (HRTEM), selected area electron diffraction (SAED) patterns and energy dispersive X-ray spectroscopy (EDS) confirmed the presence of Co inside the nanotubes. The encapsulated Co was further identified always as high temperature alpha-Co phase with fcc structure, which frequently consists of twinned boundaries and stacking faults. Based on the experimental results, a possible growth mechanism of the Co-filled CNTs was proposed.

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Sol-gel derived Ba(Mg1/3Ta2/3)O3 thin films: Preparation and structure

Journal of Materials Research ◽

10.1557/jmr.1997.0087 ◽

1997 ◽

Vol 12 (3) ◽

pp. 596-599 ◽

Cited By ~ 6

Author(s):

Ji Zhou ◽

Qing-Xin Su ◽

K. M. Moulding ◽

D. J. Barber

Keyword(s):

Thin Films ◽

Annealing Temperature ◽

Volume Fraction ◽

Sol Gel ◽

X Ray Diffraction ◽

X Ray ◽

Transmission Electron ◽

Sol Gel Process ◽

Small Grains

Ba(Mg1/3Ta2/3)O3 thin films were prepared by a sol-gel process involving the reaction of barium isopropoxide, tantalum ethoxide, and magnesium acetate in 2-methoxyethanol and subsequently hydrolysis, spin-coating, and heat treatment. Transmission electron microscopy, x-ray diffraction, and Raman spectroscopy were used for the characterization of the thin films. It was shown that the thin films tend to crystallize with small grains sized below 100 nm. Crystalline phase with cubic (disordered) perovskite structure was formed in the samples annealed at a very low temperature (below 500 °C), and well-crystallized thin films were obtained at 700 °C. Although disordered perovskite is dominant in the thin films annealed below 1000 °C, a low volume fraction of 1 : 2 ordering domains was found in the samples and grows with an increase of annealing temperature.

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Synthesis and characterization of thermosensitive and polarity-sensitive fluorescent PNIPAM-coated gold nanoparticles

e-Polymers ◽

10.1515/epoly-2016-0247 ◽

2017 ◽

Vol 17 (1) ◽

pp. 65-70 ◽

Cited By ~ 1

Author(s):

Chunhua Luo ◽

Meijuan Qian ◽

Qiujing Dong

Keyword(s):

Photoelectron Spectroscopy ◽

Au Nanoparticles ◽

Synthesis And Characterization ◽

Strong Fluorescence ◽

X Ray ◽

Transmission Electron ◽

Vis Spectroscopy ◽

Grafting Through ◽

Polarity Sensitive

AbstractThermosensitive PNIPAM-coated Au nanoparticles (AuNPs@P(NIPAM-co-MADMAC)) were synthesized by the radical “grafting through” copolymerization of 4-methacryloyloxy-4′-dimethylaminochalcone (MADMAC), MAEL-capped AuNPs and N-isopropylacrylamide (NIPAM) using azobisisobutyronitrile (AIBN) as the initiator. AuNPs@P(NIPAM-co-MADMAC) were characterized by transmission electron microscopy (TEM), ultraviolet-visible (UV-Vis) spectroscopy, thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), 1H nuclear magnetic resonance (NMR), and Fourier transform infrared (FTIR) spectroscopy. AuNPs@P(NIPAM-co-MADMAC) exhibited thermo-sensitivity from poly(NIPAM-co-MADMAC) chains and sensitive fluorescence from the MADMAC group. AuNPs@P(NIPAM-co-MADMAC) showed weak fluorescence after the temperature increased from 25°C to 45°C, or after β-cyclodextrin (β-CD) was added. Furthermore, it exhibited strong fluorescence when the solvent was changed to ethanol or chloroform.

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Controlling the Microstructure and Magnetic Properties of Ferromagnetic Nanocrystals Produced by Ion Implantation

MRS Proceedings ◽

10.1557/proc-703-v9.4 ◽

2001 ◽

Vol 703 ◽

Author(s):

K.S. Beaty ◽

A. Meldrum ◽

J.P. Franck ◽

K. Sorge ◽

J. R. Thompson ◽

...

Keyword(s):

Magnetic Properties ◽

Ion Implantation ◽

Magnetic Circular Dichroism ◽

Magnetic Hysteresis ◽

Near Surface ◽

Magnetic Elements ◽

Transmission Electron ◽

Wide Range ◽

Co Nanoparticles

ABSTRACTIon implantation coupled with annealing is a versatile and flexible approach to creating ferromagnetic near-surface nanocomposites that represent a wide range of particle/host combinations. We have used ion implantation and thermal processing to create a layer of Co nanoparticles in a sapphire host that was subsequently irradiated with Xe, Pt, or Pb in order to systematically modify the magnetic properties of the composite. Transmission electron microscopy (reported in an accompanying paper in this volume) was used to carry out a detailed characterization of the microstructure of the resulting near-surface composites whose magnetic properties were determined using SQUID magnetometry or magnetic circular dichroism. These composites exhibit magnetic hysteresis with coercivities ranging from near zero (i.e., superparamagnetism) up to 1.2 kG - depending on the composition and microstructure. We also present the results of preliminary experiments in which we attempt to control the spatial distribution of magnetic elements within ion-implanted ferromagnetic nanocomposites. The results demonstrate methods for tailoring the magnetic properties of nanocomposites produced by ion implantation for specific applications.

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TEM Characterization of Two Spark Plasma Sintered Fe-1.5wt.%Mo Steels Stabilized with SiO2 and TiO2

Materials Science Forum ◽

10.4028/www.scientific.net/msf.604-605.187 ◽

2008 ◽

Vol 604-605 ◽

pp. 187-201

Author(s):

Marcello Cabibbo

Keyword(s):

Volume Fraction ◽

Microscopy Study ◽

Electron Microscopy Study ◽

Fine Grained ◽

Plasma Sintering ◽

Transmission Electron ◽

Fine Grained Structure ◽

Spark Plasma ◽

Boundary Stability

This paper presents a transmission electron microscopy study of two Fe-1.5wt.%Mo steels stabilized with 1.5wt.%SiO2 and 1.5wt.%TiO2,respectively, and compacted through spark plasma sintering. The microstructure inspections revealed that sintered FeMo+SiO2 is able to maintain a nanometric scale grained structure up to a sintering temperature of 815°C, while the steel modified with TiO2 retained its nanometric scale microstructure up to 900°C. The ultra-fine grained structure (within 100-150 nm) was also directly correlated to the grain boundary stability through systematic extinction contours survey. Local nano-welding phenomena shows the effective compacting process of the Fe-Mo powders during sintering. Residual nano-porosity was found to decorate most of the grain boundaries and the triple grain junctions in all the sintering conditions examined, although this nano-porosity accounted for values within 0.26% in volume fraction.

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Synthesis and Characterization of Resorcinarene-Encapsulated Nanoparticles

MRS Proceedings ◽

10.1557/proc-581-59 ◽

1999 ◽

Vol 581 ◽

Cited By ~ 10

Author(s):

Alexander Wei ◽

Kevin B. Stavens ◽

Stephen V. Pusztay ◽

Ronald P. Andres

Keyword(s):

Au Nanoparticles ◽

Surface Enhanced Raman Spectroscopy ◽

Inorganic Nanoparticles ◽

Transmission Electron ◽

Surface Enhanced ◽

New Strategy ◽

Surface Enhanced Raman ◽

20 Nm ◽

Encapsulated Nanoparticles

ABSTRACTA new strategy for stabilizing inorganic nanoparticles in nonpolar solutions is described. Resorcinarenes 1-3 were synthesized and evaluated as surfactants because of their large concave headgroups with multiple contact sites. Au nanoparticles ranging from 3-20 nm in diameter were generated in the vapor phase and dispersed into dilute hydrocarbon solutions of 1-3, where they were stabilized for up to several months. Chemisorption is most likely mediated by multiple Au-O interactions, as indicated by several control experiments and by surface-enhanced Raman spectroscopy. The resorcinarenes were readily displaced by dodecanethiol, which resulted in the precipitation of particles >5 nm as determined by absorption spectroscopy and transmission electron microscopy. This suggests that the mobility of the resorcinarene tailgroups are important for maintaining the larger nanoparticles in a dispersed state. Resorcinarene surfactants with stronger chemisorptive properties are currently being explored.

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Characterization of Precipitation in Al-Zn-Mg-Cuand Li Containing Al-Zn-Mg-Cu Alloys after Isothermal Aging

Materials Science Forum ◽

10.4028/www.scientific.net/msf.546-549.977 ◽

2007 ◽

Vol 546-549 ◽

pp. 977-982 ◽

Cited By ~ 1

Author(s):

Zhi Wei Du ◽

B.L. Shao ◽

A.S. Liu ◽

Z.M. Sun ◽

X.S. Zhang ◽

...

Keyword(s):

Volume Fraction ◽

Precipitate Size ◽

X Ray Scattering ◽

Cu Alloys ◽

Transmission Electron ◽

Integrated Intensity ◽

Isothermal Ageing ◽

Evolution Of Microstructure ◽

Thermodynamic Phase

The evolution of microstructure, precipitate size, volume fraction and integrated intensity of Al-8.0Zn-2.05Mg-1.76Cu (7055) and 7055-1.0Li alloys during isothermal ageing has been studied by transmission electron microscopy (TEM) and synchrotron-radiation small angle X-ray scattering (SAXS). According to the TEM results, referring to the thermodynamic phase diagram, it was found that the addition of Li changed the types of the precipitates. T1 phase was observed in the 7055-1.0Li alloy besides the GP zones, η' and η with variant orientations with matrix, η1、η2 and η4. The super-lattice spots of L12 (Cu3Au) structure were probably due to the existence of Al3Li (δ') or Al3(Zr,Li). Furthermore, the precipitation sequence has been modified in Li-containing Al-Zn-Mg-Cu alloys. The precipitate volume fraction derived from the integrated intensity for 7055 alloy reached an plateau except ageing at 120°C and the maximum was about 0.052-0.054 in the temperature range 140-160°C.

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Microscopical Study of Au Nanocrystals Self-Assembled on (100)Si and SiO2/(100)Si Substrates

MRS Proceedings ◽

10.1557/proc-0959-m17-26 ◽

2006 ◽

Vol 959 ◽

Author(s):

Emanuela Piscopiello ◽

Leander Tapfer ◽

Marco Vittori Antisari ◽

Pasquale Paiano ◽

Paola Prete ◽

...

Keyword(s):

Self Assembly ◽

Au Nanoparticles ◽

Microscopical Study ◽

X Ray Diffraction ◽

X Ray ◽

Si Substrates ◽

Au Film ◽

Assembly Method ◽

Transmission Electron

ABSTRACTThis work reports on the structural characterization of Au nanocrystals directly prepared on the surface of (100)Si and 150 nm-thick SiO2 deposited (100)Si substrates, by a physical self-assembly method, consisting in the UHV evaporation of a thin Au film and its successive high temperature annealing. The morphology, orientation, and crystalline structure of Au nanocrystals were characterized by scanning and high-resolution transmission electron microscopy and X-ray diffraction, respectively. Experimental results show that the nature of the substrate strongly influences the process of Au nanocrystal formation upon heat treatment, by affecting the interaction of deposited Au with the underlying material. In the case of clean (100)Si substrates the Au strongly interacts with Si, so that Au nanoislands are obtained with a well defined epitaxial relationships with the substrate, i.e. [100]AuÐÐ[110]Si and [110]AuÐÐ[311]Si. The nanoisland shape is affected by faceting at the Au/Si interface, the Au nanocrystal being limited by the {111}, {311}, {711} and {-111} planes of Si. In the case of SiO2/(100)Si substrates spherical shaped Au nanoparticles with random crystal orientation are instead, produced.

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Characterization of γ′ Precipitates in Cast Ni-Based Superalloy and Their Behaviour at High-Homologous Temperatures Studied by TEM and in Situ XRD

Materials ◽

10.3390/ma13102397 ◽

2020 ◽

Vol 13 (10) ◽

pp. 2397 ◽

Cited By ~ 3

Author(s):

Łukasz Rakoczy ◽

Ondrej Milkovič ◽

Bogdan Rutkowski ◽

Rafał Cygan ◽

Małgorzata Grudzień-Rakoczy ◽

...

Keyword(s):

Volume Fraction ◽

Matrix Material ◽

High Volume ◽

Lattice Parameter ◽

X Ray Diffraction ◽

In Situ Xrd ◽

Transmission Electron ◽

The Matrix

In situ X-ray diffraction and transmission electron microscopy has been used to investigate René 108 Ni-based superalloy after short-term annealing at high-homologous temperatures. Current work is focused on characterisation of γ′ precipitates, their volume fraction, evolution of the lattice parameter of γ and γ′ phases and misfit parameter of γ′ in the matrix. Material in the initial condition is characterised by a high-volume fraction (over 63%) of γ′ precipitates. Irregular distribution of alloying elements was observed. Matrix channels were strongly enriched in Cr, Co, W and Mo, whereas precipitates contain large amount of Al, Ti, Ta and Hf. Exposure to high-homologous temperatures in the range 1100–1250 °C led to the dissolution of the precipitates, which influenced the change of lattice parameter of both γ and γ′ phases. The lattice parameter of the matrix continuously grew during holding at high temperatures, which had a dominant influence on the more negative misfit coefficient.

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