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185 results on '"Tang, Y.L."'

33. PFO sorted s-SWNT networks for optoelectronics

Author

Gaufrès, Étienne, Tang, Y.l., ALVAREZ, Laurent, Martel, R., IZARD, Nicolas, Laboratoire Charles Coulomb (L2C), Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), Regroupement Québécois sur les Matériaux de Pointe (RQMP), and École Polytechnique de Montréal (EPM)-Université de Sherbrooke (UdeS)-McGill University = Université McGill [Montréal, Canada]-Université de Montréal (UdeM)-Fonds Québécois de Recherche sur la Nature et les Technologies (FQRNT)

Subjects
[PHYS.PHYS.PHYS-OPTICS]Physics [physics]/Physics [physics]/Optics [physics.optics], [SPI.OPTI]Engineering Sciences [physics]/Optics / Photonic, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci]
Abstract

International audience; The rise of efficient extraction techniques triggered a renewal of interest in semiconducting carbon nanotubes (s-SWNT) research. It represents a great interest for optoelectronics, with outstanding properties in field-effect transistor, and s-SWNT ability to efficiently emit light in the near-IR range. In particular, polyfluorene (PFO) wrapped s‑SWNT (s-SWNT@PFO) display strong photoluminescence, and could be coupled with photonic devices such as microring resonators [1,2] to control photoluminescence linewidth and enhance photoluminescence intensity.The main challenge for using s-SWNT@PFO in optoelectronics lies in the difficulty to establish good electrical contact with a PFO embedded carbon nanotube. We propose to investigate these issues by tuning the amount of PFO wrapping around s-SWNT. A low pressure annealing process is used to selectively remove PFO around s‑SWNT without burning nanotubes themselves (Figure). The resulting s-SWNT@PFO networks are then probed by AFM, Raman spectroscopy, absorption, photoluminescence and electrical experiments.

Published
2017

36. Maximizing loop squareness by minimizing gradients in the microstructure

Author

Branagan, D.J., Kramer, M.J., Tang, Y.L., and McCallum, R.W.

Subjects
Alloys -- Research, Physics
Abstract

Six elements were added to the base Nd2Fe14B (2-14-1) composition to reduce its sensitivity to localized changes in cooling rate and control grain growth through crystallization. It is shown that the modified alloy leads to uniform hard magnetic properties over a wide range of cooling rates. The improvements in the magnetic properties and the bulk method used to characterize microstructural inhomogeneities based on loop shape are discussed.

Published
1999

47. An effect of crystal tilt on the determination of ions displacements in perovskite oxides under BF/HAADF-STEM imaging mode.

Author

Liu, Y., Zhu, Y.L., Tang, Y.L., and Ma, X.L.

Subjects
ION analysis, ELECTRIC properties of crystals, PEROVSKITE synthesis, FERROELECTRIC crystals, SCANNING transmission electron microscopy
Abstract

Effects of crystal tilt on the determination of the relative positions of different ion columns in compounds such as ferroelectric PbTiO3 are of critical importance, because the displacements of Ti and O relative to Pb correlate directly to the spontaneous polarization and ferroelectric properties. Here a study about the effects of small-angle crystal tilt on the relative image spots positions of different ions in PbTiO3 was carried out under high angle angular dark-field (HAADF) and bright-field imaging for aberration corrected Scanning Transmission Electron Microscope. The results indicate that crystal tilt affects the relative positions of Pb, Ti, and O greatly, and the effects are proved to depend highly on crystal tilt angle and PTO thickness. HAADF image simulations on PbTiO3, SrTiO3, and SrRuO3 indicate that the difference in atomic number is a main contributor to the relative image spot position change of different ion columns when crystal tilts. [ABSTRACT FROM AUTHOR]

Published
2017
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48. 3D polarization texture of a symmetric 4-fold flux closure domain in strained ferroelectric PbTiO3 films.

Author

Tang, Y.L., Zhu, Y.L., Hong, Z.J., Eliseev, E.A., Morozovska, A.N., Wang, Y.J., Liu, Y., Xu, Y.B., Wu, B., Chen, L.Q., Pennycook, S.J., and Ma, X.L.

Subjects
COUPLING reactions (Chemistry), POLARIZATION (Electrochemistry), FERROELECTRIC crystals, SCANNING transmission electron microscopy, DIPOLE bonds
Abstract

Although the strong coupling of polarization to spontaneous strain in ferroelectrics would impart a flux-closure with severe disclination strains, recent studies have successfully stabilized such a domain via a nano-scaled multi-layer growth. Nonetheless, the detailed distributions of polarizations in three-dimensions (3D) and how the strains inside a flux closure affect the structures of domain walls are still less understood. Here we report a 3D polarization texture of a 4-fold flux closure domain identified in tensile strained ferroelectric PbTiO3/SrTiO3 multilayer films. Ferroelectric displacement analysis based on aberration-corrected scanning transmission electron microscopic imaging reveals highly inhomogeneous strains with strain gradient above 107/m. These giant disclination strains significantly broaden the 90° domain walls, while the flexoelectric coupling at 180° domain wall is less affected. The present observations are helpful for understanding the basics of topological dipole textures and indicate novel applications of ferroelectrics through engineering strains. [ABSTRACT FROM AUTHOR]

Published
2017
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