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50 results on '"Shen, J.C."'

30. Characterization of Hg-Ba-Ca-Cu-O 1223 superconductor

Author

Rui, Y., primary, Ji, H.L., additional, Shao, H.M., additional, Xu, X.N., additional, Qin, M.J., additional, Shen, J.C., additional, Jin, X., additional, Yao, X.X., additional, Rong, X.S., additional, Ying, B., additional, Che, G.C., additional, and Zhao, Z.X., additional

Published
1994
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40. Irreversibility and transport in the high Tcsuperconductor HgBa2Ca2Cu3O8 + δ

Author

Wu, J.G., Shao, H.M., Ding, S.Y., Yao, X.X., Shen, J.C., and Wu, Z.

Abstract

A HgBa2Ca2Cu3O8 + δsuperconductor, having a Tcof 133 K (oxygen-annealed sample), was successfully synthesized. A.c. susceptibility, electrical resistivity and critical current density measurements were performed. The irreversibility line (IL) was obtained and a new feature of 1 − t ∝ H1/4(t = Tirr/Tcis the reduced temperature, where irris the irreversibility temperature) was found and explained in terms of T. Matsushita's theory. The results of the transport measurements can be looked upon as evidence that there also might be a vortex glass-liquid transition in Hg-based systems. The dimensions of the superconducting CuO2layer for different compounds was used to explain the observed transition in the IL.

Published
1996
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41. White light emission induced by confinement in organic multiheterostructures.

Author

Xie, Z.Y., Huang, J.S., Li, C.N., Liu, S.Y., Wang, Y., Li, Y.Q., and Shen, J.C.

Subjects
ELECTROCHEMICAL apparatus, HETEROSTRUCTURES, LIGHT emitting diodes
Abstract

Proposes a technique for the fabrication and characterization of white-light organic electrochemical devices from multiheterostructures. Configuration for white-light emitting diodes;. Use of triphenyldiamine derivative as a hole-transporting layer; Maximum brightness and luminous efficiency of the device.

Published
1999
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49. Determination of surface oxygen vacancy position in SnO2 nanocrystals by Raman spectroscopy

Author

Liu, L.Z., Wu, X.L., Gao, F., Shen, J.C., Li, T.H., and Chu, Paul K.

Subjects
*SURFACE defects, *OXYGEN, *STANNIC oxide, *NANOCRYSTALS, *RAMAN spectroscopy, *DENSITY functionals
Abstract

Abstract: Raman spectra acquired from SnO2 nanocrystals with different sizes show a size-independent Raman mode at ∼574 cm−1. The intensity increases as the nanocrystal size decreases and this tendency is contrary to that of the normal bulk Raman modes. By considering the existence of oxygen vacancies at the nanocrystal surface, we adopt the density functional theory to calculate the Raman spectra with different oxygen vacancy positions and concentrations. The results clearly demonstrate that the in-plane oxygen vacancy is responsible for the 574 cm−1 mode and the intensity enhancement is a result of the higher in-plane oxygen vacancy concentration. [Copyright &y& Elsevier]

Published
2011
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50. Splitting of X-ray diffraction peak in (Ge:SiO2)/SiO2 multilayers

Author

Li, J., Wu, X.L., Hu, D.S., Yang, Y.M., Qiu, T., and Shen, J.C.

Subjects
*NANOCRYSTALS, *TRANSMISSION electron microscopes, *LAYER structure (Solids), *ANNEALING of crystals
Abstract

(Ge:SiO2)/SiO2 multilayers were fabricated for exploring the influence of the stress on the structure of Ge nanocrystals. When annealed at 800 °C, the multilayers show a clear splitting (fine structure) of the Ge (220) X-ray diffraction peak and have a preferred orientation. Similar effects cannot take place in the multilayers annealed at higher or lower temperature. Analyses of Raman scattering, X-ray diffraction spectroscopy, and transmission electron microscope observations suggest that the observed phenomena arise from compressive stress exerted on Ge nanocrystals, which is induced by the confinement of both the SiO2 matrix in the cosputtered layer and neighboring SiO2 layers. The stress may cause an orthorhombic distortion of the diamond structure of bulk Ge. This will lead to the disappearance of the (111) and (311) diffraction peaks and the splitting of the (220) peak. This kind of (Ge:SiO2)/SiO2 multilayers enables us to control the sizes of the Ge crystallites and enhance the stress, and is thus promising in forming new nanocrystal structures. [Copyright &y& Elsevier]

Published
2004
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