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Full-Text Articles in Nanoscience and Nanotechnology

Toward Tailored Functionality Of Titania Nanotube Arrays: Interpretation Of The Magnetic-Structural Correlations, Pegah M. Hosseinpour, Eugen Panaitescu, Don Heiman, Latika Menon, Laura H. Lewis Dec 2013

Toward Tailored Functionality Of Titania Nanotube Arrays: Interpretation Of The Magnetic-Structural Correlations, Pegah M. Hosseinpour, Eugen Panaitescu, Don Heiman, Latika Menon, Laura H. Lewis

Donald Heiman

Ordered arrays of titania nanotubes (NTs) are considered as good candidates for photocatalytic applications including water splitting. Considering that the functionality of these nanostructures is influenced by their morphology, electronic and the crystallographic structure, fundamental understanding of these properties and their possible correlations can clarify the approaches toward enhanced photocatalytic efficiency. In this work, ordered arrays of titania NTs are synthesized electrochemically and are subjected to isochronal annealing treatments in various atmospheres (oxygen-rich, oxygen-deficient and reducing) to modify their morphology, crystal and electronic structure. Upon characterization of these NTs, direct correlations are found between the annealing atmosphere and the corresponding …


Nanophase Stability In A Granular Ferh-Cu System, Radhika Barua, Felix Jiménez-Villacorta, J. E. Shield, D. Heiman, L. H. Lewis Aug 2013

Nanophase Stability In A Granular Ferh-Cu System, Radhika Barua, Felix Jiménez-Villacorta, J. E. Shield, D. Heiman, L. H. Lewis

Donald Heiman

A granular system of FeRh-based nanoprecipitates (∼10–15 nm diameter) embedded in a rapidly solidified copper ribbon matrix was found to transit from a metastable tetragonal L10 (AuCu-1-type) structure to a stable B2 (CsCl-type) structure upon annealing-induced coarsening to ∼94 nm. The hysteretic magnetic transition observed at ∼100 K develops a gradual broadening that accompanies the L10 → B2 crystal structure transition. It is proposed that the Cu matrix influences the structural and magnetic properties of the FeRh-based nanoparticles through interfacial strain and chemical effects. These results emphasize the sensitivity of the magnetostructural response of FeRh to changes in the nanostructural …


Tuning The Magnetostructural Phase Transition In Ferh Nanocomposites, Radhika Barua, Xiujuan Jiang, Felix Jiménez-Villacorta, J. Shield, D. Heiman, L. Lewis Aug 2013

Tuning The Magnetostructural Phase Transition In Ferh Nanocomposites, Radhika Barua, Xiujuan Jiang, Felix Jiménez-Villacorta, J. Shield, D. Heiman, L. Lewis

Donald Heiman

Effects of nanostructuring on the magnetostructural response of the near-equiatomic FeRh phase were investigated in nanocomposite materials synthesized by rapid solidification and subsequent annealing of an alloy of nominal atomic composition (FeRh)5Cu95. Transmission electron microscopy studies confirm attainment of a phase-separated system of nanoscaled (∼10–15 nm diameter) precipitates, consistent with FeRh embedded in a Cu matrix. These nanoprecipitates are crystallographically aligned with the coarse-grained Cu matrix and possess an L10-type (CuAu 1) structure, in contrast to the B2 (CsCl)-type structure of bulk FeRh. It is proposed that the face-centered cubic crystal structure of the …