Magnetic properties of nanoparticles fabricates viainert gas condensation.

K. Coughlin, L. Zhai, R. Kraft, M.M. PattersonUniversity 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.

BackgroundExploration 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.

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.

Figure 1. High-resolution transmission electron microscopy (HRTEM) image of a single FePt particle (photo M. Patterson)

Figure 2. Example of sizes from nano to Nascar (picture from www.nano.gov)

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 3. Bell Jar assembly diagram. Inset: our bell jar and test chamber being prepared for a test.

Figure 4. diagram of equipment and lab set up

Acknowledgements

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

References

Principles of Plasma Discharges and Materials Processing, Michael A. Lieberman, Allan J. Lichtenberg - Wiley-Interscience (2005) 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. 273-376, 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.

In Progress• 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.

Figure 5. Previous synthesis of FePt nanoparticles in N2 plasma

Power supply

RFRF power

Main power supply

Rough Pump

Collector

Diffusion Pump

Bell Jar and base

Argon Gas

Figure 6. SEM image of manufactured FePt particles