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High-resolution Transmission Electron Microscope (high-resolution + transmission_electron_microscope)

Distribution by Scientific Domains

Polymers and Materials Science	80%

Selected Abstracts

Formation of Chiral Mesopores in Conducting Polymers by Chiral-Lipid-Ribbon Templating and "Seeding" Route,

ADVANCED FUNCTIONAL MATERIALS, Issue 18 2008
Chaxing Fan
Abstract Conducting polymer nanofibers with controllable chiral mesopores in the size, the shape, and handedness have been synthesized by chiral lipid ribbon templating and "seeding" route. Chiral mesoporous conducting poly(pyrrole) (CMPP) synthesized with very small amount of chiral amphiphilic molecules (usually,<,3%) has helically twisted channels with well-defined controllable pore size of 5,20,nm in central axis of the twisted fibers. The structure and chirality of helical mesopores have been characterized by high-resolution transmission electron microscope (HRTEM), scanning electron microscope (SEM) and electron tomography. The average pore diameters of chiral mesopores were approximately estimated from the N2 adsorption,desorption data and calculated by the conversion calculation from helical ribbons to a rectangular straight tape. The pore size of CMPP has been controlled by choosing different alkyl chain lengths of chiral lipid molecules or precisely adjusting the H2O/EtOH volume ratio. [source]

Fabrication of Crack-Free C12A7 Nano-Ceramics Composite from Eutectic Glass in the C12A7,CaYAlO4 System

INTERNATIONAL JOURNAL OF APPLIED CERAMIC TECHNOLOGY, Issue 4 2006
Naonori Sakamoto
Crack formation in the C12A7 nano-composite during crystallization was successfully avoided by using the eutectic glass in the C12A7,CaYAlO4 system. The crystal phases from the eutectic glass were identified to be C12A7 (major phase) and CaYAlO4 (minor phase) by X-ray diffraction and high-resolution transmission electron microscope. It was indicated that origin of cracks upon crystallization of C12A7 glass was the volume expansion caused by crystallization of C12A7 in the glass and the cracking could be avoided by the volume shrinkage by crystallization of CaYAlO4. By using a conventional molding technique, we have also succeeded to fabricate a bulk C12A7 composite with arbitrary shapes. [source]

Investigation of the effects of partial coherence on exit wave reconstruction

JOURNAL OF MICROSCOPY, Issue 1 2004
L. J. ALLEN
Summary In a recent work we presented an iterative wave function reconstruction (IWFR) method that reconstructs a wave function from measurements of its amplitude taken as it propagates in free space (a focal series of images). Although the ideal environment for application of the IWFR method is in a coherent imaging system, it has been developed so that it can be applied in a partially coherent imaging system, in particular for a high-resolution transmission electron microscope using a field-emission gun. In this paper we investigate the effects of partial coherence on the accuracy of results obtained using the IWFR method. We then show how results obtained under such conditions can be improved by estimating and subtracting components from the amplitude measurements of the wave function that derive from incoherence in the electron beam. [source]

Nanosized CdSe Particles Synthesized by an Air Pressure Solution Process Using Ethylene-Glycol-Based Solvent

JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 7 2010
Tao Wang
Nanosized CdSe particles were synthesized at a temperature of 115°,175°C by a solution method with air pressure condition. Ethylene glycol (EG) was used as the main solvent and sodium selenite and cadmium nitrate-tetrahydrate as inorganic sources. The influence of refluxing temperature and time on growth morphology and crystallization was investigated by transmission electron microscope, high-resolution transmission electron microscope, and X-ray diffraction. The chemical reaction was deducted based on X-ray photoelectron spectra. The optical absorption property was measured by UV-vis. The CdSe nanoparticles synthesized through this EG solvent system was single wurtzite crystallization and had a nanoscale size below 15 nm diameter with a narrow size distribution. The reduction of Se4+,Se0,Se2,and the disproportionation of Se0 occurred during the synthetic process and dominated the chemical reaction. [source]

Preparation and shear properties of carbon nanotubes/poly(butyl methacrylate) hybrid material

POLYMER COMPOSITES, Issue 9 2008
Wen-Hua Li
Composites containing carbon nanotubes (CNTs) in a poly(butyl methacrylate) (PBMA) have been prepared by in situ polymerization. Scanning electron microscopy and high-resolution transmission electron microscope showed that CNTs were well dispersed into PBMA matrix and wrapped with PBMA. The infrared spectrum illustrated that CNTs were covalently linked with PBMA through a CC bond. Owing to this covalent linkage, the composites had a better solubility in organic solvents and had higher thermal stability over pure PBMA. The direct shear testing showed strong mechanical behavior with up to 200% increase in Young's modulus. The possible strengthening mechanism was discussed. POLYM. COMPOS., 2008. © 2008 Society of Plastics Engineers [source]