AVS 53rd International Symposium
    Thin Film Thursday Sessions
       Session TF-ThP

Paper TF-ThP12
Formation of Magnetic Iron Oxide Films from Decomposition of Ferric Acetylacetonate on Cold Substrates

Thursday, November 16, 2006, 5:30 pm, Room 3rd Floor Lobby

Session: Thin Film Poster Session
Presenter: S. De Dea, University of California, San Diego
Authors: S. De Dea, University of California, San Diego
D. Graziani, University of California, San Diego
D.R. Miller, University of California, San Diego
R.E. Continetti, University of California, San Diego
Correspondent: Click to Email
Ferric acetylacetonate Fe(acac)@sub 3@ is known to undergo thermal decomposition to form either Fe@sub 3@O@sub 4@ or @alpha@-Fe@sub 2@O@sub 3@ magnetically ordered materials when heated above 180°C. We have recently observed that magnetically ordered Fe@sub 3@O@sub 4@ and @alpha@-Fe@sub 2@O@sub 3@ can be formed near room temperature conditions in an inert atmosphere when a supercritical solution of Fe(acac)@sub 3@ in CO@sub 2@ is sprayed in a supersonic free-jet onto a cold Si substrate. This process is referred to as Rapid Expansion of Supercritical Solutions (RESS), and we originally anticipated the need to grow the thin cluster films on a heated substrate in an oxygen environment. We have now grown films in background pressures from vacuum to atmosphere and in both air and inert gases. The resulting cluster films have particles in the range from 50 nm to 800 nm, depending on experimental conditions, and have been analyzed by SEM, SQUID, and Mossbauer spectroscopy. The measured coercivities for the thin films range from 50 Oe to 100 Oe. These data suggest that we have grown Fe@sub 3@O@sub 4@ and @alpha@-Fe@sub 2@O@sub 3@, even on cold substrates in both inert and oxidizing gas backgrounds. We were able to identify @alpha@-Fe@sub 2@O@sub 3@ on the basis of the Morin transition and we are currently performing additional measurements to confirm that the other magnetically ordered phase is Fe@sub 3@O@sub 4@ . In order to better understand the mechanism for the decomposition, we are in the process of introducing a time-of-flight mass spectrometer probe of the jet conditions before the solution impacts the substrate. To remove the effects of the free-jet expansion, which can provide considerable translational energy to the impinging Fe(acac)@sub 3@ molecules and clusters, we are also preparing to use the supercritical solution in a batch experiment in a closed cell.