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  1. Effect of Fe-Doping on Structural and Magnetic Properties of TitaniaNanotubesLaura H. Lewis, Northeastern University, DMR 0906608 Outcome A magnetic semiconductor material, Fe-doped titanium dioxide (titania) has been created in the form of a high density of vertically aligned nanotube arrays. Impact Such materials will impact the field of spintronics which will enable high speed devices utilizing less power than current electronic devices. Explanation Titania is a semiconductor material and is used extensively in various applications pertaining to optics, electronics and even biology. Incorporation of small amounts of ‘magnetic’ entities such as Fe atoms introduces magnetic properties in the material making it a magnetic semiconductor with multifunctional applications, spintronics, optics and electronics. The creation of the structures in the nanotube architecture is an additional advantage since novel devices in nanoscale form can be envisioned. Such structures are being synthesized by a team of researchers at Northeastern University by utilization of a simple, inexpensive electrochemical route. The materials are being investigated for their structural and magnetic properties and device applications are being explored. Image (Right) shows the top view image of a vertically aligned array of Fe-containing titaniananotubes

  2. Synthesis of Fe-Doped TitaniaNanotubeArrays Laura H. Lewis, Northeastern University, DMR 0906608 (i) Route 1 - Thermally evaporated Fe on electrochemically synthesized titaniananotubes (ii) Route 2 - Fe-doped TitaniaNanotubes electrochemically synthesized from Fe-Ti alloy EDX showing presence of Fe in TitaniaNanotubes Evidence of Room temperature Ferromagnetism in Fe-doped titaniananotubes (at % 1.8) – preliminary results

  3. Role of Annealing Atmosphere on Morphology and Magnetic Properties of TitaniaNanotubes Laura H. Lewis, Northeastern University, DMR 0906608 Structural Properties of UndopedTitaniaNanotubes Magnetic Properties of UndopedTitaniaNanotubes 1 mm H = 0.4T Oxygen-rich annealing atmosphere produces polycrystalline nanotubes with intact tube structure • Magnetic signal arises from two components • Pauli paramagnetism possibly from titania • Possible ferromagnetic/antiferromagneticcomponent due to oxygen vacancy • - Further investigation is underway Oxygen-deficient atmosphere (for example, annealing in argon gas) produces single crystal nanoparticles on the original nanotubular scaffold

  4. Educational ImpactLaura H. Lewis, Northeastern University, DMR 0906608 1. Actively supporting & mentoring post-doctoral researchers, grad, & undergrad. students Post-doctoral Researcher: EugenPanaitescu PhD Student: PegahHosseinpour, Chemical Engineering (Conference Presentations: MRS 2010, APS 2011, IEEE Summer School 2011, MRS 2011 (to be presented)) Mohamed AbdElmoula, Physics (graduated summer 2011) (Conference Presentations: APS 2011, MRS 2010, NSTI 2011) Undergraduate student: Josh Morris 2. Weekly Nanogroup and Nanomagnetism Meetings: Forum for presentation of research results and discussion of new ideas 3. Outreach– Sponsored high school student under Research Science Institute program James Lim (Massachusetts) – Summer 2011 Mohamed AbdElmoula ‘s research presentation NU Nanogroup