Browsing by Author "Zhang, X."
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- Analysis of 2-dimensional transient problems for linear elastic and piezoelectric structures using the consecutive-interpolation quadrilateral element (CQ4)Tinh, Q. B.; Du, D. N.; Zhang, X.; Hirose, S.; Batra, Romesh C. (Elsevier, 2016-07-01)
- Experimentally engineering the edge termination of graphene nanoribbonsZhang, X.; Yazyev, O. V.; Feng, J.; Xie, L.; Tao, C.; Chen, Y. C.; Jiao, L.; Pedramrazi, Z.; Zettl, A.; Louie, S. G.; Dai, H.; Crommie, M. F. (2013-01-22)The edges of graphene nanoribbons (GNRs) have attracted much interest due to their potentially strong influence on GNR electronic and magnetic properties. Here we report the ability to engineer the microscopic edge termination of high-quality GNRs via hydrogen plasma etching. Using a combination of high-resolution scanning tunneling microscopy and first-principles calculations, we have determined the exact atomic structure of plasma-etched GNR edges and established the chemical nature of terminating functional groups for zigzag, armchair, and chiral edge orientations. We find that the edges of hydrogen-plasma-etched GNRs are generally flat, free of structural reconstructions, and terminated by hydrogen atoms with no rehybridization of the outermost carbon edge atoms. Both zigzag and chiral edges show the presence of edge states.
- Joint Determination of Reactor Antineutrino Spectra from U-235 and Pu-239 Fission by Daya Bay and PROSPECTAn, F. P.; Andriamirado, M.; Balantekin, A. B.; Band, H. R.; Bass, C. D.; Bergeron, D. E.; Berish, D.; Bishai, M.; Blyth, S.; Bowden, N. S.; Bryan, C. D.; Cao, G. F.; Cao, J.; Chang, J. F.; Chang, Y.; Chen, H. S.; Chen, S. M.; Chen, Y.; Chen, Y. X.; Cheng, J.; Cheng, Z. K.; Cherwinka, J. J.; Chu, M. C.; Classen, T.; Conant, A. J.; Cummings, J. P.; Dalager, O.; Deichert, G.; Delgado, A.; Deng, F. S.; Ding, Y. Y.; Diwan, M.; Dohnal, T.; Dolinski, M. J.; Dolzhikov, D.; Dove, J.; Dwyer, D. A.; Erickson, A.; Foust, B. T.; Gaison, J. K.; Galindo-Uribarri, A.; Gallo, J. P.; Gilbert, C. E.; Gonchar, M.; Gong, G. H.; Gong, H.; Grassi, M.; Gu, W. Q.; Guo, J. Y.; Guo, L.; Guo, X. H.; Guo, Y. H.; Guo, Z.; Hackenburg, R. W.; Hans, S.; Hansell, A. B.; He, M.; Heeger, K. M.; Heffron, B.; Heng, Y. K.; Hor, Y. K.; Hsiung, Y. B.; Hu, B. Z.; Hu, J. R.; Hu, T.; Hu, Z. J.; Huang, H. X.; Huang, J. H.; Huang, X. T.; Huang, Y. B.; Huber, P.; Koblanski, J.; Jaffe, D. E.; Jayakumar, S.; Jen, K. L.; Ji, X. L.; Ji, X. P.; Johnson, R. A.; Jones, D. C.; Kang, L.; Kettell, S. H.; Kohn, S.; Kramer, M.; Kyzylova, O.; Lane, C. E.; Langford, T. J.; LaRosa, J.; Lee, J.; Lee, J. H. C.; Lei, R. T.; Leitner, R.; Leung, J. K. C.; Li, F.; Li, H. L.; Li, J. J.; Li, Q. J.; Li, R. H.; Li, S.; Li, S. C.; Li, W. D.; Li, X. N.; Li, X. Q.; Li, Y. F.; Li, Z. B.; Liang, H.; Lin, C. J.; Lin, G. L.; Lin, S.; Ling, J. J.; Link, Jonathan M.; Littenberg, L.; Littlejohn, B. R.; Liu, J. C.; Liu, J. L.; Liu, J. X.; Lu, C.; Lu, H. Q.; Lu, X.; Luk, K. B.; Ma, B. Z.; Ma, X. B.; Ma, X. Y.; Ma, Y. Q.; Mandujano, R. C.; Maricic, J.; Marshall, C.; McDonald, K. T.; McKeown, R. D.; Mendenhall, M. P.; Meng, Y.; Meyer, A. M.; Milincic, R.; Mueller, P. E.; Mumm, H. P.; Napolitano, J.; Naumov, D.; Naumova, E.; Neilson, R.; Nguyen, T. M. T.; Nikkel, J. A.; Nour, S.; Ochoa-Ricoux, J. P.; Olshevskiy, A.; Palomino, J. L.; Pan, H. -R.; Park, J.; Patton, S.; Peng, J. C.; Pun, C. S. J.; Pushin, D. A.; Qi, F. Z.; Qi, M.; Qian, X.; Raper, N.; Ren, J.; Reveco, C. Morales; Rosero, R.; Roskovec, B.; Ruan, X. C.; Searles, M.; Steiner, H.; Sun, J. L.; Surukuchi, P. T.; Tmej, T.; Treskov, K.; Tse, W. -H.; Tull, C. E.; Tyra, M. A.; Varner, R. L.; Venegas-Vargas, D.; Viren, B.; Vorobel, V.; Wang, C. H.; Wang, J.; Wang, M.; Wang, N. Y.; Wang, R. G.; Wang, W.; Wang, W.; Wang, X.; Wang, Y.; Wang, Y. F.; Wang, Z.; Wang, Z.; Wang, Z. M.; Weatherly, P. B.; Wei, H. Y.; Wei, L. H.; Wen, L. J.; Whisnant, K.; White, C.; Wilhelmi, J.; Wong, H. L. H.; Woolverton, A.; Worcester, E.; Wu, D. R.; Wu, F. L.; Wu, Q.; Wu, W. J.; Xia, D. M.; Xie, Z. Q.; Xing, Z. Z.; Xu, H. K.; Xu, J. L.; Xu, T.; Xue, T.; Yang, C. G.; Yang, L.; Yang, Y. Z.; Yao, H. F.; Ye, M.; Yeh, M.; Young, B. L.; Yu, H. Z.; Yu, Z. Y.; Yue, B. B.; Zavadskyi, V.; Zeng, S.; Zeng, Y.; Zhan, L.; Zhang, C.; Zhang, F. Y.; Zhang, H. H.; Zhang, J. W.; Zhang, Q. M.; Zhang, S. Q.; Zhang, X.; Zhang, X. T.; Zhang, Y. M.; Zhang, Y. X.; Zhang, Y. Y.; Zhang, Z. J.; Zhang, Z. P.; Zhang, Z. Y.; Zhao, J.; Zhao, R. Z.; Zhou, L.; Zhuang, H. L.; Zou, J. H. (American Physical Society, 2022-02-22)A joint determination of the reactor antineutrino spectra resulting from the fission of U235 and Pu239 has been carried out by the Daya Bay and PROSPECT Collaborations. This Letter reports the level of consistency of U235 spectrum measurements from the two experiments and presents new results from a joint analysis of both data sets. The measurements are found to be consistent. The combined analysis reduces the degeneracy between the dominant U235 and Pu239 isotopes and improves the uncertainty of the U235 spectral shape to about 3%. The U235 and Pu239 antineutrino energy spectra are unfolded from the jointly deconvolved reactor spectra using the Wiener-SVD unfolding method, providing a data-based reference for other reactor antineutrino experiments and other applications. This is the first measurement of the U235 and Pu239 spectra based on the combination of experiments at low- and highly enriched uranium reactors.
- Novel high temperature multilayer electrode-barrier structure for high-density ferroelectric memoriesBhatt, H. D.; Desu, Seshu B.; Vijay, Dilip P.; Hwang, Y. S.; Zhang, X.; Nagata, M.; Grill, A. (AIP Publishing, 1997-08-01)This has been accomplished in the past using four/five separate electrode- and diffusion-barrier layers. In this letter, we report a novel Pt-Rh-O-x/Pt-Rh/Pt-Rh-O-x electrode-barrier structure which acts as an electrode as well as a diffusion barrier for integration of the ferroelectric capacitors directly onto silicon deposited using an in situ reactive rf sputtering process. The electrodes have a smooth and fine grained microstructure and are excellent diffusion barriers between the PbZr0.53Ti0.47O3 (PZT) and Si substrate and exhibit good thermal stability up to very high processing temperatures of 700 degrees C. The ferroelectric (PZT) test capacitors using these electrode barriers grown directly on Si, show well saturated hysteresis loops with P-r and E-c of 16 mu C/cm(2) and 30-40 kV/cm, respectively. The capacitors exhibit no significant fatigue loss (<5%) up to 10(11) cycles and have low leakage currents (2X10(-8) A/cm(2) at 100 kV/cm). These electrode barriers can be used to directly integrate the thin film capacitors on the source/drain of the transistors of the memory cell structure for accomplishing large scale integration. (C) 1997 American Institute of Physics.
- Oriented growth of SrBi2Ta2O9 ferroelectric thin filmsDesu, Seshu B.; Vijay, Dilip P.; Zhang, X.; He, B. P. (AIP Publishing, 1996-09-01)We report on the ferroelectric properties of c-axis oriented ferroelectric SrBi2Ta2O9 thin films. Pt/SrBi2Ta2O9/Pt capacitors were grown on single crystal MgO (and/or SrTiO3) substrates using pulsed laser ablation. These substrates provide the necessary template for (100) texture in platinum due to their close lattice matching. This in turn facilitates the c-axis orientation in the ferroelectric films. The degree of orientation in the layered structure ferroelectric film was systematically varied from highly c-axis oriented to random polycrystalline by varying the growth conditions of the bottom metal electrode. The polarization and coercive field values were found to decrease with an increasing degree of c-axis orientation; while the randomly oriented films exhibited a remnant polarization of 5 mu C/cm(2), a coercive field of 70 kV/cm, and a dielectric constant of 320, the c-axis oriented films exhibited very low polarization (similar to 1 mu C/cm(2)), coercivity (22 kV/cm), and dielectric constant (similar to 200) values. (C) 1996 American Institute of Physics.
- Properties of SrBi2Ta2O9 ferroelectric thin films prepared by a modified metalorganic solution deposition techniqueJoshi, Pooran C.; Ryu, S. O.; Zhang, X.; Desu, Seshu B. (AIP Publishing, 1997-03-01)Polycrystalline SrBi2Ti2O9 thin films having a layered-perovskite structure were fabricated by a modified metalorganic solution deposition technique using room temperature processed alkoxide-carboxylate precursor solution. It was possible to obtain a complete perovskite phase at an annealing temperature of 650 degrees C and no pyrochlore phase was observed even up to 600 degrees C. In addition, the SrBi2Ta2O9 thin films annealed at 750 degrees C exhibited better structural, dielectric, and ferroelectric properties than those reported by previous techniques. The effects of postdeposition annealing on the structural, dielectric, and ferroelectric properties were analyzed. The electrical measurements were conducted on Pt/SrBi2Ta2O9/Pt capacitors. The typical measured small signal dielectric constant and dissipation factor at 100 kHz were 330 and 0.023 and the remanent polarization and the coercive field were 8.6 mu C/cm(2) and 23 kV/cm, respectively, for 0.25-mu m-thick films annealed at 750 degrees C. The leakage current density was lower than 10(-8) A/cm(2) at an applied electric Weld of 150 kV/cm. The films showed good switching endurance under bipolar stressing at least up to 10(10) switching cycles. (C) 1997 American Institute of Physics.
- Reconstruction Of Sectional Images in Holography Using Inverse ImagingZhang, X.; Lam, Edmund Y.; Poon, Ting-Chung (Optical Society of America, 2008-01-01)This paper discusses the reconstruction of sectional images from a hologram generated by optical scanning holography. We present a mathematical model for the holographic image capture, which facilitates the use of inverse imaging techniques to recover individual sections. This framework is much more flexible than existing work, in the sense that it can handle objects with multiple sections, and possibly corrupted with white Gaussian noise. Simulation results show that the algorithm is capable of recovering a prescribed section while suppressing the other ones as defocus noise. The proposed algorithm is applicable to on-axis holograms acquired by conventional holography as well as phase-shifting holography. (C) 2008 Optical Society of America
- Thin films of layered-structure (1-x)SrBi2Ta2O9-xBi(3)Ti(Ta1-yNby)O-9 solid solution for ferroelectric random access memory devicesDesu, Seshu B.; Joshi, Pooran C.; Zhang, X.; Ryu, S. O. (AIP Publishing, 1997-08-01)We report on the thin films of solid-solution material (1-x)SrBi2Ta2O9-xBi(3)Ti(Ta1-yNby)O-9 fabricated by a modified metalorganic solution deposition technique for ferroelectric random access memory devices. Using the modified technique, it was possible to obtain the pyrochlore free crystalline thin films at an annealing temperature as low as 600 degrees C. The solid-solution of layered perovskite materials helped us to significantly improve the ferroelectric properties, higher P-r and higher T-c, compared to SrBi2Ta2O9; a leading candidate material for memory applications. For example, the films with 0.7 SrBi2Ta2O9-0.3Bi(3)TiTaO(9) composition and annealed in the temperature range 650-750 degrees C exhibited 2 P-r and E-c values in the range 12.4-27.8 mu C/cm(2) and 68-80 kV/cm, respectively. The leakage current density was lower than 10(-8) A/cm(2) at an applied electric field of 200 kV/cm. The films exhibited good fatigue characteristics under bipolar stressing. (C) 1997 American Institute of Physics.