Record Details

Imaging of magnetic colloids under the influence of magnetic field by cryogenic transmission electron microscopy

DSpace at IIT Bombay

View Archive Info
 
 
Field Value
 
Title Imaging of magnetic colloids under the influence of magnetic field by cryogenic transmission electron microscopy
 
Creator WU, J
ASLAM, M
DRAVID, VP
 
Subject cobalt nanoparticle rings
dipolar chains
flux-closure
zero-field
nanocrystals
 
Description The application of superparamagnetic nanoparticles for in vivo magnetic resonance imaging (MRI) under external ac magnetic field has attracted considerable research efforts in recent years. However, it is unclear how superparamagnetic nanostructures arrange themselves in fluidic environment under external magnetic field. Here, we report direct visualization of the effect of applied magnetic field to the ferrofluids (about 6 nm superparamagnetic magnetite (Fe(3)O(4)) nanoparticle "colloidal" suspension) using the cryogenic transmission electron microscopy (cryo-TEM). While long dipole chains (up to millimeter range) of the magnetite along the magnetic lines are found in samples dried inside the magnetic field, only short dipole chains (within tens of nanometer scale) with random orientations are observed in the wet sample observed by cryo-TEM. In the wet sample, aggregations of medium-length dipole chains (up to hundreds of nanometer) can be observed at the areas where the nanoparticles are "solidified" when phase separation occurs. In situ formation of flux-closure rings is observed at the edge where vitreous ice sublimes due to high-energy electron radiation that leaves magnetite nanoparticles isolated in the vacuum. Such observations may help elucidate the nature of magnetic field-induced assembly in fluidic environment as in the physiological aqueous conditions in MRI and related applications. (C) 2008
 
Publisher AMER INST PHYSICS
 
Date 2011-07-16T07:23:21Z
2011-12-26T12:49:39Z
2011-12-27T05:35:12Z
2011-07-16T07:23:21Z
2011-12-26T12:49:39Z
2011-12-27T05:35:12Z
2008
 
Type Article
 
Identifier APPLIED PHYSICS LETTERS, 93(8), -
0003-6951
http://dx.doi.org/10.1063/1.2976751
http://dspace.library.iitb.ac.in/xmlui/handle/10054/4361
http://hdl.handle.net/10054/4361
 
Language en