Magnetic properties of nanoparticles fabricates via
inert gas condensation.
K. Coughlin, L. Zhai, R. Kraft, M.M. Patterson
University of Wisconsin–Stout, Menomonie, WI 54751
Introduction
The purpose of this research is to observe and study the
effects of temperature variations on the formation of and
magnetic properties of Iron/Platinum (FePt) nanoparticles.
We hope to find properties that will suggest that FePt
particles can be used for magnetic recording in computer
storage devices or as a replacement to currently used rare
earth metals.
Apparatus
(FePt Particle Synthesis)
• Argon gas is pumped into the bell jar vacuum chamber
• A voltage is applied to the FePt target plate
• Ar+ ions and electrons oscillate between two plates at
high velocities
• Sputtering occurs when ions collide with FePt atoms on
the target, knocking them off of the plate
• Aggregation (direct mutual attraction between particles)
occurs when Liquid N₂ cools the plasma into clusters in
the condensing region
Figure 6. SEM image of manufactured FePt
particles
In Progress
Figure 1. High-resolution transmission electron
microscopy (HRTEM) image of a single FePt particle
(photo M. Patterson)
Background
Exploration of the properties of alloys has existed since the
first days of smelting iron in approximately 2500BC. Today,
alloys are used in virtually every man made structure,
electronics device, and tool manufactured. As those tools
advance, we are able to study the properties of materials on
a much smaller and smaller scale.
Figure 3. Bell Jar assembly diagram. Inset: our bell jar
and test chamber being prepared for a test.
Main power supply
Power supply
Bell Jar and base
RF
power
References
RF
Principles of Plasma Discharges and Materials Processing,
Michael A. Lieberman, Allan J. Lichtenberg - Wiley-Interscience
(2005)
Rough
Pump
Diffusion Pump
Argon Gas
Collector
Figure 4. diagram of equipment and lab set up
MM Patterson, A Cochran, J Ferina, X Rui, TA Zimmerman, Z Sun,
MJ Kramer, DJ Sellmyer, JE Shield, "Early stages of direct L10 FePt
nanocluster formation: the effects of plasma characteristics",
Journal of Vacuum Science and Technology B, Vol 28 (2), pp. 273376, March 2010.
MM Patterson, X Rui, XZ Li, JE Shield, DJ Sellmyer, "Plasma ion
heating produces L10 FePt nanoclusters", Materials Research
Society Symposium Proceedings, 1087E (V08), 2008.
Figure 2. Example of sizes from nano to Nascar
(picture from www.nano.gov)
When a material gets closer to the nanoscale, its properties
can vary from accepted industry standards. When the
number of atoms or molecules bonded together is so small
that they occupy between 1 and 100 nanometers of space,
the properties are no longer predictable.
•Colors displayed can change based on the amount of
atoms present to reflect light.
•Due to the small mass of some particles, gravitational
forces are negligible, giving way to electromagnetic forces
that determine behavior.
• Setup of equipment and fluid/gas routing systems
• Manufacturing of particles (nanomagnets) of various
sizes
• Measurement of size (SEM, AFM) and magnetic
characteristics (magnetometer).
• Exploring nano scale sized magnetic alternatives to rare
earth alloys.
Acknowledgements
Figure 5. Previous synthesis of FePt nanoparticles in N2
plasma
We gratefully acknowledge support from a UW-Stout
Faculty Research Initiative SEED Grant; the NanoSTEM
DIN; the UW-Stout Department of Physics; Shawn Kozey,
Nate Hughes, Jacob Smith, Morgan Lowery, Mark Sala,
Craig Hineline, Lucas Johnson, Ben Tredinnick, Ryan Schele
and SPGNSFB