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Synthesis of magnetic nanofibers using femtosecond laser material processing in air.

Alubaidy MA, Venkatakrishnan K, Tan B - Nanoscale Res Lett (2011)

Bottom Line: The nanofibers diameter varies between 30 and 70 nm and they are mixed with nanoparticles.X-ray diffraction (XRD) analysis revealed metallic and oxide phases in the nanostructure.The growth of magnetic nanostructure is highly recommended for the applications of magnetic devices like biosensors and the results suggest that the pulsed-laser method is a promising technique for growing nanocrystalline magnetic nanofibers and nanoparticles for biomedical applications.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Mechanical Engineering, Ryerson University, 350 Victoria Street, Toronto, ON, M3N 2H8, Canada. venkat@ryerson.ca.

ABSTRACT
In this study, we report formation of weblike fibrous nanostructure and nanoparticles of magnetic neodymium-iron-boron (NdFeB) via femtosecond laser radiation at MHz pulse repetition frequency in air at atmospheric pressure. Scanning electron microscopy (SEM) analysis revealed that the nanostructure is formed due to aggregation of polycrystalline nanoparticles of the respective constituent materials. The nanofibers diameter varies between 30 and 70 nm and they are mixed with nanoparticles. The effect of pulse to pulse separation rate on the size of the magnetic fibrous structure and the magnetic strength was reported. X-ray diffraction (XRD) analysis revealed metallic and oxide phases in the nanostructure. The growth of magnetic nanostructure is highly recommended for the applications of magnetic devices like biosensors and the results suggest that the pulsed-laser method is a promising technique for growing nanocrystalline magnetic nanofibers and nanoparticles for biomedical applications.

No MeSH data available.


Related in: MedlinePlus

SEM image of magnetic nanofibrous structure and nanoparticles on NdFeB substrate irradiated with femtosecond laser at 26 MHz repetition rate and 15 W average power.
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Figure 1: SEM image of magnetic nanofibrous structure and nanoparticles on NdFeB substrate irradiated with femtosecond laser at 26 MHz repetition rate and 15 W average power.

Mentions: The energy of the femtosecond laser is delivered into the material in a short time scale that absorption occurs at nearly solid-state. The energy is first deposited in the electronic subsystem within a layer of thickness of tens of nanometer. Enough energy is absorbed to produce macroscopic ablation when the density of the free electrons exceeds a certain threshold [21]. The ionized material is removed away from the surface in the form of expanding high pressure plasma. The plasma remains confined close to the specimen surface at atmospheric pressure. Condensation of vapor in the plume leads to the generation of nanoparticles. Some of these nanoparticles aggregate and then get deposited on the surface of the specimen [8]. Vapor condensation starts with nucleation, proceeds with growth of supercritical nucleus and come to a halt due to quenching. For nanoparticles to aggregate and form fibrous structure, a continuous supply of vapor is required to the expanding plume to maintain the nucleus density. Hence nanoparticles generated from the successive laser pulse are fused to the particles created from the previous laser pulse that are still above the melting temperature and grow as nanofibrous like structure as shown in Figure 1. Dipole-dipole interactions then trigger anisotropic chain growth under the influence of serendipitous Brownian collisions, attractive van der Waals, as well as the residual electrostatic repulsions that maintain colloidal stability [22]. The energy barrier to surface reorganization is overcome over the very high temperature, resulting in the rapid onset of self-assembly of the nanoparticle chains (or nanofibers).


Synthesis of magnetic nanofibers using femtosecond laser material processing in air.

Alubaidy MA, Venkatakrishnan K, Tan B - Nanoscale Res Lett (2011)

SEM image of magnetic nanofibrous structure and nanoparticles on NdFeB substrate irradiated with femtosecond laser at 26 MHz repetition rate and 15 W average power.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211468&req=5

Figure 1: SEM image of magnetic nanofibrous structure and nanoparticles on NdFeB substrate irradiated with femtosecond laser at 26 MHz repetition rate and 15 W average power.
Mentions: The energy of the femtosecond laser is delivered into the material in a short time scale that absorption occurs at nearly solid-state. The energy is first deposited in the electronic subsystem within a layer of thickness of tens of nanometer. Enough energy is absorbed to produce macroscopic ablation when the density of the free electrons exceeds a certain threshold [21]. The ionized material is removed away from the surface in the form of expanding high pressure plasma. The plasma remains confined close to the specimen surface at atmospheric pressure. Condensation of vapor in the plume leads to the generation of nanoparticles. Some of these nanoparticles aggregate and then get deposited on the surface of the specimen [8]. Vapor condensation starts with nucleation, proceeds with growth of supercritical nucleus and come to a halt due to quenching. For nanoparticles to aggregate and form fibrous structure, a continuous supply of vapor is required to the expanding plume to maintain the nucleus density. Hence nanoparticles generated from the successive laser pulse are fused to the particles created from the previous laser pulse that are still above the melting temperature and grow as nanofibrous like structure as shown in Figure 1. Dipole-dipole interactions then trigger anisotropic chain growth under the influence of serendipitous Brownian collisions, attractive van der Waals, as well as the residual electrostatic repulsions that maintain colloidal stability [22]. The energy barrier to surface reorganization is overcome over the very high temperature, resulting in the rapid onset of self-assembly of the nanoparticle chains (or nanofibers).

Bottom Line: The nanofibers diameter varies between 30 and 70 nm and they are mixed with nanoparticles.X-ray diffraction (XRD) analysis revealed metallic and oxide phases in the nanostructure.The growth of magnetic nanostructure is highly recommended for the applications of magnetic devices like biosensors and the results suggest that the pulsed-laser method is a promising technique for growing nanocrystalline magnetic nanofibers and nanoparticles for biomedical applications.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Mechanical Engineering, Ryerson University, 350 Victoria Street, Toronto, ON, M3N 2H8, Canada. venkat@ryerson.ca.

ABSTRACT
In this study, we report formation of weblike fibrous nanostructure and nanoparticles of magnetic neodymium-iron-boron (NdFeB) via femtosecond laser radiation at MHz pulse repetition frequency in air at atmospheric pressure. Scanning electron microscopy (SEM) analysis revealed that the nanostructure is formed due to aggregation of polycrystalline nanoparticles of the respective constituent materials. The nanofibers diameter varies between 30 and 70 nm and they are mixed with nanoparticles. The effect of pulse to pulse separation rate on the size of the magnetic fibrous structure and the magnetic strength was reported. X-ray diffraction (XRD) analysis revealed metallic and oxide phases in the nanostructure. The growth of magnetic nanostructure is highly recommended for the applications of magnetic devices like biosensors and the results suggest that the pulsed-laser method is a promising technique for growing nanocrystalline magnetic nanofibers and nanoparticles for biomedical applications.

No MeSH data available.


Related in: MedlinePlus