Browsing by Author "Feng, Y"

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    COARSEMAP: synthesis of observations and models for coarse-mode aerosols
    (American Geophysical Union, 2017-12-11) Wiedinmyer, C; Lihavainen, H; Mahowald, NM; Alastuey, A; Albani, S; Artaxo, P; Bergametti, G; Batterman, S; Brahney, J; Duce, RA; Feng, Y; Buck, C; Ginoux, PA; Chen, Y; Guieu, C; Cohen, DD; Hand, JL; Harrison, RM; Herut, B; Ito, A; Losno, R; Gomez, D; Kanakidou, M; Landing, WM; Laurent, B; Mihalopoulos, N; Mackey, K; Maenhaut, W; Heuglin, C; Milando, C; Miller, RL; Myriokefaitakis, S; Neff, JC; Pandolfi, M; Paytan, A; Pérez, CGP; Prank, M; Prospero, JM; Tamburo, E; Varrica, D; Wong, MY; Zhang, Y
    Coarse mode aerosols influence Earth’s climate and biogeochemistry by interacting with long-wave radiation, promoting ice nucleation, and contributing important elements to biogeochemical cycles during deposition. Yet coarse mode aerosols have received less emphasis in the scientific literature. Here we present first efforts to globally synthesize available mass concentration, composition and optical depth data and modeling for the coarse mode aerosols (<10 µm) in a new project called “COARSEMAP” (http://www.geo.cornell.edu/eas/PeoplePlaces/Faculty/mahowald/COARSEMAP/). We seek more collaborators who have observational data, especially including elemental or composition data, and/or who are interested in detailed modeling of the coarse mode. The goal will be publications synthesizing data with models, as well as providing synthesized results to the wider community.
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    Critical role of the coupling between the octahedral rotation and a-site ionic displacements in PbZrO3-based antiferroelectric materials investigated by in situ neutron diffraction
    (American Physical Society, 2017-12-21) Lu, T; Studer, AJ; Yu, DH; Withers, RL; Feng, Y; Chen, H; Islam, SS; Xu, Z; Liu, Y
    This in situ neutron-diffraction study on antiferroelectric (AFE) Pb0.99(Nb0.02Zr0.65Sn0.28Ti0.05)O3 polycrystalline materials describes systematic structural and associated preferred orientation changes as a function of applied electric field and temperature. It is found that the pristine AFE phase can be poled into the metastable ferroelectric (FE) phase at room temperature. At this stage, both AFE and FE phases consist of modes associated with octahedral rotation and A-site ionic displacements. The temperature-induced phase transition indicates that the octahedral rotation and ionic displacements are weakly coupled in the room-temperature FE phase and decoupled in the high-temperature FE phase. However, both temperature and E-field-induced phase transitions between the AFE and high-temperature FE phase demonstrate the critical role of coupling between octahedral rotation and A-site ionic displacements in stabilizing the AFE structure, which provides not only experimental evidence to support previous theoretical calculations, but also an insight into the design and development of AFE materials. Moreover, the associated preferred orientation evolution in both AFE and FE phases is studied during the phase transitions. It is found that the formation of the preferred orientation can be controlled to tune the samples’ FE and AFE properties. ©2017 American Physical Society - Open access
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    Susceptible ferroelectric/antiferroelectric phase transition near the surface of Nb-doped lead zirconate stannate titanate from surface processing
    (American Chemical Society, 2016-05-23) Lu, T; Studer, AJ; Cortie, DL; Lau, K; Yu, DH; Feng, Y; Chen, H; Xu, Z; Withers, RL; McIntyre, GJ; Liu, Y
    This work systematically investigated the structure and property of the near-surface and bulk regions of Pb0.99(Nb0.02Zr0.73Sn0.21Ti0.04)O3 ceramics using a combination of X-ray and neutron diffraction, piezoresponse force microscopy, and conventional ferroelectric/piezoelectric characterization. It is found that mechanical force can induce an antiferroelectric/ferroelectric phase transition within micrometers of the surface. Such a phase transition is strongly dependent on the processing scenario, leading to differences from the bulk region. This work provides crucial insights into the sensitivity of this class of AFE materials. Clearly, surface processing conditions must be taken into account for both accurate structural determination and practical applications. © 2016 American Chemical Society