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Bulletin of the Korean Chemical Society (BKCS)

ISSN 0253-2964(Print)
ISSN 1229-5949(Online)
Volume 11, Number 5
BKCSDE 11(5)
May 20, 1990 

Preparation, Structure, and Photoemission Studies on the High Temperature Superconductor YBa2Cu3-xNixO7-δ
Jin-Ho Choy*, Won-Young Choe
YBa2Cu3-xNixO7-δ, with x = 0.05, 0.2, 0.4, 0.7 and 1.0 had been prepared by the thermal decomposition of corresponding nitrates. Among them, the sample with x = 0.05 shows above-liquid-N2 temperature superconductivity with Tc of 88.7K. According to the X-ray diffraction analysis, its crystal symmetry was estimated as orthorhombic with the lattice parameters of a = 3.866Å, b = 3.893Å, c = 11.715Å. The chemical composition of the sample was determined by electron probe microanalysis and the chemical composition around its grain boundaries was carefully studied by the X-ray line scanning technique. From the observed binding energy of Ni-2p3/2 orbital electron (B.E. = 853 eV) measured by X-ray photoelectron spectroscopy, the valency state of nickel stabilized in YBa2Cu2.95Ni0.05O7-δ, oxide lattice could be determined to be Ni(Ⅱ).
379 - 383
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