Proton Beam Irradiation Effects on Magnetic Nanocomposites
- PDF / 73,960 Bytes
- 5 Pages / 612 x 792 pts (letter) Page_size
- 79 Downloads / 220 Views
R3.25.1
Proton Beam Irradiation Effects on Magnetic Nanocomposites M. Chipara, M. J. Zaleski1, D. Hui2, D. L. Pelecky3 S. Balascuta4. Indiana University Cyclotron Facility, Bloomington, IN. 1 Chemistry Department, Indiana University, Bloomington, IN. 2 University of New Orleans. 3 Physics Department, University of Nebraska, Lincoln, NE. 4 Physics Department, Indiana University, Bloomington, IN.
ABSTRACT
A magnetic nanocomposite material has been obtained by dispersing ball milled magnetic nanoparticles of barium ferrite within a styrene- isoprene- styrene block copolymer, sonicating the solution, and spin coating it onto a quartz crystal. Ferromagnetic resonance spectra of pristine and irradiated magnetic nanocomposites are reported. Although the flux of incoming protons was not large, modifications in the ferromagnetic resonance spectra were noticed. This suggests that the future ultra high-density media would present an enhanced sensitivity to the radiation component of the space environment.
INTRODUCTION
Magnetic nanocomposites have a wide range of near future applications; one of the most important is the ultra high-density data storage media. The combined use of magnetic nanoparticles and of block copolymers will further reduce the production costs and enhance the performance, as it is expected that the self-assembly capabilities of polymeric matrices will result in a regular distribution of magnetic nanoparticles [1]. The nanopatterning of the ultra highdensity media will be a consequence of the system (block copolymer + magnetic nanoparticle) search for the free energy minimum. The capabilities of some magnetic nanocomposites as future ultra high density media has been proven. Nevertheless, the continuous decrease in the size of magnetic features is actually reaching two limits. The first one is where thermal motion becomes comparable to magnetic interaction and as a result of the motional averaging, the nanoparticles will present superparamagnetic features. Superparamagnetic materials cannot be used as magnetic media as they do no have a hysteresis loop (the coercive field is almost zero). The other limit, due also to the reduction in the volume of the magnetic grain, reflects the increase in the sensitivity of the magnetic feature to environmental conditions, and in particular, to ionizing radiation. Such investigations are of particular interest to NASA, due to the potential adverse effect of the radiation component of the space environment on nanomaterials and devices based on nanomaterials. Barium titanate nanoparticles are among the candidates for the future ultra high-density media materials. The magnetic properties of this material have been discussed elsewhere [2-5].
R3.25.2
EXPERIMENTAL METHODS
Magnetic nanocomposite materials have been obtained by dispersing barium ferrite (BaFe) nanoparticles in a dilute solution of styrene-isoprene-styrene block copolymer (SIS) in toluene. The magnetic nanoparticles were obtained by mechanical milling. From the analysis of X Ray diffraction lines, the av
Data Loading...
