# Nanoparticles

Many metal alloys can form in chemically ordered structures, often resulting in significant changes in properties. The ordered structures are preferred at low temperatures and will go through an order-disorder phase transition at a critical temperature. The formation and stability of these ordered structures in alloy nanoparticles is not well understood but may give insight into the role size plays in phase transitions.

To this end we are studying CoPt, AuCu, and FeNiPt alloy nanoparticles. We characterize these nanoparticles in a Transmission Electron Microscope (TEM) for composition, size, and structure. These nanoparticles are made by co-sputtering the constituents and annealing at different temperatures in various gas mixtures. The nanoparticle samples are prepared for TEM viewing by wedge polishing.

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# Nanoparticles

![TEM image of magnetic alloy nanoparticles](nanoparticles_1.jpg)

Many metal alloys can form in chemically ordered structures, often resulting  in significant changes in properties. The ordered structures are preferred at  low temperatures and will go through an order-disorder phase  transition at a critical temperature. The formation and stability of these  ordered structures in alloy nanoparticles is not well understood but  may give insight into the role size plays in phase transitions.

![Diffraction pattern showing material properties of magnetic alloy nanoparticles](nanoparticles_2.jpg)

To this end we are studying CoPt, AuCu, and FeNiPt alloy nanoparticles. We characterize  these nanoparticles in a Transmission Electron Microscope (TEM) for composition,  size, and structure. These nanoparticles are made by co-sputtering the constituents  and annealing at different temperatures in various gas mixtures. The nanoparticle  samples are prepared for TEM viewing by wedge polishing.

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