Structural Characterization of Ordered Phases in Hydrocarbon Dendrimers

1994 ◽  
Vol 351 ◽  
Author(s):  
Christopher J. Buchko ◽  
Atisa Sioshansi ◽  
Zhifu Xu ◽  
Jeffrey S. Moore ◽  
David C. Martin
Keyword(s):  
Structural Characterization ◽  
Rational Design ◽  
Structural Information ◽  
Molecular Architecture ◽  
Thermal Transitions ◽  
Self Assembling ◽  
Transmission Electron ◽  
Ordered Phases ◽  
Construction Of Self

ABSTRACTStructural characterization of phenylacetylene dendrimers (PADs) makes it possible to explore the relationship between molecular architecture and condensed phase organization. The size and geometry of the PAD series is precisely controlled, with phenylacetylene units emanating from a central phenylene in the manner of a tridendron. The branched molecule rapidly increases in size with each synthetic generation. The “shape-persistent” nature of the phenylacetylene molecule makes it ideal for use in the construction of self-assembling supramolecular systems.Transmission electron microscopy (TEM) has been used to identify the crystal structure of lower generation PADs, and wide-angle X-ray studies confirm the decrease in crystallinity with size. Hot stage optical microscopy studies of thermal transitions reveal melting points for lower generation PADs, and an apparent glass transition for the amorphous higher generations. This type of structural information is essential to the rational design of self-assembling materials.

scholarly journals MICROWAVE ASSISTED SYNTHESIS AND STRUCTURAL CHARACTERIZATION OF NICKEL OXIDE NANOPARTICLES

2016 ◽  
Vol 3 (1) ◽  
pp. 12-14
Author(s):  
Kalpanadevi K ◽  
Manimekalai R
Keyword(s):  
Electron Microscope ◽  
Nickel Oxide ◽  
Structural Characterization ◽  
Nano Particles ◽  
Microwave Assisted Synthesis ◽  
Nio Nanoparticles ◽  
Nickel Oxide Nanoparticles ◽  
Transmission Electron ◽  
Good Crystallinity

Nickel oxide (NiO) nano-particles were produced via a simple microwave method from the Ni(OH)2 precursor, which was obtained by slow drop-wise addition of 0.1M sodium hydroxide to 0.1M nickel nitrate. The mixture was vigorously stirred until the pH reached 7.2. The mixture was then irradiated with microwave to deposit Ni(OH)2 at a better precipitation rate. Drying the precipitate at 320°C resulted in formation of NiO nanoparticles. High Resolution Transmission Electron Microscope (HRTEM), Scanning Electron Microscope (SEM) and X-ray diffraction (XRD), employed for the structural characterization of the as-prepared NiO nanoparticles, revealed their good crystallinity and high-purity. Microwave irradiation increased homogeneity and decreased the mean particle size of the produced NiO particles.

scholarly journals Rational design of functional materials guided by single particle chemiluminescence imaging

2019 ◽  
Vol 10 (21) ◽  
pp. 5444-5451 ◽  
Author(s):  
Weijun Kong ◽  
Qi Li ◽  
Wei Wang ◽  
Xiaoning Zhao ◽  
Shenglong Jiang ◽  
...  
Keyword(s):  
Structural Characterization ◽  
Single Particle ◽  
Rational Design ◽  
Functional Materials ◽  
Single Particles ◽  
Improved Performance

Correlated chemiluminescence imaging and structural characterization of single particles helped the rational design of functional materials with significantly improved performance.

Structural characterization of SmMn2GeO7 single microcrystals by electron microscopy

2005 ◽  
Vol 61 (1) ◽  
pp. 11-16 ◽  
Author(s):  
E. A. Juarez-Arellano ◽  
J. M. Ochoa ◽  
L. Bucio ◽  
J. Reyes-Gasga ◽  
E. Orozco
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Structural Characterization ◽  
Point Group ◽  
Spherical Mirror ◽  
Quaternary Compound ◽  
Cell Parameters ◽  
Transmission Electron ◽  
Electron Energy Loss

Single microcrystals of the new compound samarium dimanganese germanium oxide, SmMn2GeO7, were grown using the flux method in a double spherical mirror furnace (DSMF). The micrometric crystals were observed and chemically analysed with scanning electron microscopy (SEM) and X-ray energy dispersive spectroscopy (EDX). The structural characterization and chemical analysis of these crystals were also carried out using transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM), together with electron-energy-loss spectroscopy (EELS). We found that the new quaternary compound crystallizes in the orthorhombic system with the point group mmm (D 2h ), space group Immm (No. 71) and cell parameters a = 8.30 (10), b = 8.18 (10), c = 8.22 (10) Å and V = 558.76 Å3.

Structural Characterization of CF-PVT Grown Bulk 3C-SiC

2008 ◽  
Vol 600-603 ◽  
pp. 67-70 ◽  
Author(s):  
Alkyoni Mantzari ◽  
Frédéric Mercier ◽  
Maher Soueidan ◽  
Didier Chaussende ◽  
Gabriel Ferro ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Structural Properties ◽  
Structural Characterization ◽  
Stacking Faults ◽  
Vapor Transport ◽  
Physical Vapor Transport ◽  
Transmission Electron ◽  
Continuous Feed

The aim of the present work is to study the structural properties of 3C-SiC which is grown on (0001) 6H-SiC and on (100) 3C-SiC (Hoya) seeds using the Continuous Feed Physical Vapor Transport (CF-PVT) method. Transmission Electron Microscopy (TEM) observations confirm that the overgrown layer is of the 3C-SiC polytype. In the case of the 6H-SiC substrate, microtwins (MTs), stacking faults (SFs) and dislocations (D) are observed at the substrate-overgrown interface with most of the dislocations annihilating within the first few µm from the interface. In the case of 3C-SiC crystals grown on 3C seeds, repeated SFs are formed locally and also coherent (111) twins of 3C-SiC are frequently observed near the surface. The SF density is reduced at the uppermost part of the grown material.

scholarly journals Extracting structural information of Au colloids at ultra-dilute concentrations: identification of growth during nanoparticle immobilization

2019 ◽  
Vol 1 (7) ◽  
pp. 2546-2552 ◽  
Author(s):  
George F. Tierney ◽  
Donato Decarolis ◽  
Norli Abdullah ◽  
Scott M. Rogers ◽  
Shusaku Hayama ◽  
...  
Keyword(s):  
Absorption Spectroscopy ◽  
Structural Characterization ◽  
Structural Information ◽  
Particle Growth ◽  
Au Nanoparticle ◽  
X Ray ◽  
Colloidal Au ◽  
X Ray Absorption ◽  
Au Colloids

This paper describes the structural characterization of ultra-dilute colloidal Au nanoparticle solutions using X-ray absorption spectroscopy (XAS) and the particle growth during immobilization.

A Reactor for “Ex-Situ” TEM Catalyst Characterization

1999 ◽  
Vol 5 (S2) ◽  
pp. 926-927 ◽  
Author(s):  
C.E. Kliewer ◽  
M.M. Disko ◽  
S.L Soled ◽  
G.J. DeMartin
Keyword(s):  
Catalytic Properties ◽  
Structural Information ◽  
High Vacuum ◽  
Chemical Characterization ◽  
Ex Situ ◽  
Catalyst Characterization ◽  
Initial Development ◽  
Transmission Electron ◽  
Pressure Variable

The microstructural and chemical characterization of catalysts is not only integral to their initial development but also to understanding and controlling their behavior over time. To better elucidate the morphology of these materials and relate physical properties to catalytic properties (e.g., activity, selectivity, etc.), “ex-situ” methods for studying catalysts under reactive conditions have been developed.Because conventional transmission electron microscopy (CTEM) is conducted under high vacuum conditions, it is difficult to replicate the exact chemical environment of a catalyst (e.g., high pressure, variable gas mixtures, etc) within the TEM. Consequently, most analyses focus on comparing “fresh” and “spent” materials. In general, this methodology provides useful structural information albeit with limitations associated with the comparison of dissimilar regions and the effects of sampling inhomogenieties.

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