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    Characterization of a Cylindrical Superconductor Disk Prepared by the Wet Technique with Microstructure Analysis and Levitation Force Measurements Using a Permanent Magnet
    (PHYSICAL SOC REPUBLIC CHINA, 2009) Karaca, I.
    The levitation force between a cylindrical superconducting disk (CSCD) and a permanent magnet (Bi = 0.15 T) in the zero-field-cooled (ZFC) regime has been investigated at liquid nitrogen temperature (77 K). The CSCD showed a lower repulsive force. It was considered that the changes in the levitation force are related to the grain orientation, the homogeneity, and the number of the pinning centers in the samples. From the structural analysis, it was found that the volume percentages of the Bi-2223 and Bi-2212 phase are 81% and 19% in the CSCD, respectively. The calculated a and c lattice parameters of the Bi-2212 and Bi-2223 phases are a=b= 5.4055 angstrom (Bi-2212), 5.4102 angstrom (Bi-2223), and c = 30.7522 angstrom (Bi-2212), 37.0327 angstrom (Bi-2223), respectively.
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    Effects of ZnO addition on mechanical properties of Bi1.84Pb0.34Sr1.91Ca2.03Cu3.06O10 prepared by a wet technique
    (ELSEVIER SCIENCE SA, 2009) Karaca, I.; Uzun, O.; Koelemen, U.; Yilmaz, F.; Sahin, O.
    In this study, ZnO molar wt% 0, 5,10,20,30, and 50 added Bi1.84Pb0.34Sr1.91Ca2.03Cu3.06O10 superconductors were prepared by wet technique. The experimental works consist of powder X-ray diffraction (XRD) for phase analyses and c-axes parameters, scanning electron microscopy (SEM) for microstructure examination, and microhardness measurements for mechanical properties. These measurements showed that Zn-added material, in comparison with the pure sample, had increased c-axes parameters and decreased grain size. In addition, the experimental results of microhardness measurements were analyzed using Oliver-Pharr model. It was observed that the change of indentation hardness (H-rr) and reduced elastic modulus (E-r) values showed an increasing trend with ZnO addition and exhibited peak load dependence (i.e., indentation size effect (ISE)). (C) 2008 Elsevier B.V. All rights reserved.