Effects of ambient gas and laser fluence on the compositional changes in iron oxide particle aggregated films prepared by laser ablation
- 70 Downloads
Iron oxide nanoparticle aggregated films were prepared using the excimer laser ablation technique by adopting an off-axis configuration and a gas condensation process. Sintered iron oxide targets (αFe2O3) were ablated in Ar, O2, He, N2, Ne and Xe by an ArF excimer (193 nm) under various pressures. It was found that both the ambient gas and its pressure strongly affected the composition of the deposition product. Depending on the ablation parameters, the product of ablation was comprised of Fe2O3 or a mixture of Fe2O3 and FeO. Ablation in argon at the lowest fluence of 4.9 J/cm2 led to deposition of two oxides, FeO and Fe2O3 in the entire pressure range tested. The most pronounced change in the relative amounts of these phases was observed in the 13.3–350 Pa pressure range. Changing the Ar pressure from the lower to the upper limit of this range varied the product chemistry from being close to a single (Fe2O3) phase to being two phase (Fe2O3+FeO). Ablation experiments in all the background gases used showed that when the irradiation fluence was sufficiently high the deposition became stoichiometric (Fe/O ratio the same as that of the target) within a pressure range specific to each gas. With further increase in fluence, the pressure ranges within which the deposition was stoichiometric became broadened. Changes in the product chemistry were analyzed in terms of the energetics of the ablated species. For monoatomic gases, the maximum pressure (PS (X)) at which the product was still a single Fe2O3 phase decreased monotonically with increasing atomic mass of the gas at lower fluence, and at higher fluence this dependence became non-monotonic. Diatomic gases, such as N2 and O2, were more efficient in cooling down the evaporated species, leading to non-stoichiometric deposition even at lower pressures.
KeywordsFe2O3 Iron Oxide Pressure Range Iron Oxide Nanoparticle Iron Oxide Particle
Unable to display preview. Download preview PDF.
- 1.A.H. Morrish: The Principles of Magnetism (Wiley, New York 1960) Chapt. 7Google Scholar
- 2.L. Gunter: In Magnetic Properties of Fine Particles, ed. by J. Dorman, D. Fiorani (Elsevier, Amsterdam 1992) p. 213Google Scholar
- 7.T. Yoshida, Y. Yamada, T. Orii, S. Takeyama: 1995 Inter. Conf. Solid State Devices and Materials, Osaka, Extended Abstract (Publication Office, Japanese Journal of Applied Physics, Tokyo 1995) p. 968Google Scholar
- 11.C.P. Grigoropoulos: In Laser Ablation and Desorption, ed. by J.C. Miller, R.F. Haglund (Academic Press, San Diego 1998) pp. 173–223Google Scholar
- 15.D.H. Lowndes: In Laser Ablation and Desorption, ed. by J.C. Miller, R.F. Haglund (Academic Press, San Diego 1998) pp. 475–571Google Scholar
- 18.D.R. Lide (Ed.): CRC Handbook of Chemistry and Physics, 81st edn. (CRC Press LLC, Boca Raton 2000–2001)Google Scholar