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X-ray photoemission studies of Zn doped Cu1-xTlxBa2Ca2Cu 3-yZnyO10-δ (y = 0, 2.65) superconductors

Khan, N. A ; Sharif University of Technology | 2007

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  1. Type of Document: Article
  2. DOI: 10.1016/j.physc.2006.12.012
  3. Publisher: 2007
  4. Abstract:
  5. The X-ray photoemission (XPS) measurements of Cu1-xTlxBa2Ca2 Cu3-yZnyO10-δ (y = 0, 2.65) superconductors have been performed and compared. These studies revealed that the charge state of thallium in the Cu0.5Tl0.5Ba2O4-δ charge reservoir layer in Zn doped samples is Tl1+, while it is a mix of Tl1+ and Tl2+ in Zn free samples. The binding energy of Ba atoms in the Zn doped samples is shifted to higher energy, which when considered along with the presence of Tl1+ suggested that it more efficiently directed the carriers to ZnO2 and CuO2 planes. The evidence of improved inter-plane coupling witnessed in X-ray diffraction is also confirmed by XPS measurements of Ca atoms in the Zn doped samples. The shift of the valance band spectrum in these Zn doped samples to higher energies suggested that the electrons at the top edge of the valance band were tied to a higher binding energy (relative to samples without Zn doping), which most likely resulted in a much lower energy state of the system in the superconducting state. The stronger superconducting state arising out of these effects is witnessed in the form of increased Tc(R = 0), Jc and the extent of diamagnetism in the final compound. © 2006 Elsevier B.V. All rights reserved
  6. Keywords:
  7. Binding energy ; Copper alloys ; Diamagnetism ; Doping (additives) ; Electron energy levels ; X ray diffraction ; X ray photoelectron spectroscopy ; Charge states ; Inter plane coupling ; Superconducting states ; Valance band spectrum ; Superconducting materials
  8. Source: Physica C: Superconductivity and its Applications ; Volume 453, Issue 1-2 , 2007 , Pages 46-51 ; 09214534 (ISSN)
  9. URL: https://www.sciencedirect.com/science/article/abs/pii/S0921453406008689