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    Crystallization Activation Energy and Hole Concentration Properties of the Bi2Sr2Ca1-xCdx, Cu2O8+y Glass-Ceramic Superconductor Rods
    (2002) Özhanh Z.; Yakinci M.E.; Balci Y.; Aksan M.A.
    The glass rods with the nominal compositions of Bi2Sr2Ca1-xCdxCu2 O8+y, where x = 0.0, 0.4, and 0.8, were prepared by melt-casting method. XRD studies exhibited that the Cd substitution caused a transition from Bi-2212 phase to Bi-2201 phase. The multiphase structure was obtained for higher Cd concentration cases. It was determined that the activation energy for crystallization was decreased with the increase of the Cd concentration. When the Cd concentration was increased in the system the superconducting properties decreased. The hole concentration, p, was calculated using the Presland's method. The increase in the Cd concentration increased the hole concentration and the results showed that the Cd-substituted samples were highly in the overdoped region. ©2002 Plenum Publishing Corporation.
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    Effects of SnO on growth and physical properties of BSCCO whiskers
    (2012) Altin S.; Aksan M.A.; Balci Y.; Yakinci M.E.
    Superconductor whiskers doped with SnO have been fabricated by annealing a melt quenched (Bi2Sn1)-223 precursor using suitable heat treatment cycles. Approximately 5 ?m thick, 90 ?m wide and 5 mm long whiskers were fabricated, and their physical, electrical and magnetic properties were investigated. Crystallisation activation energies of glass phase fabricated were calculated to be 390 kJ mol-1 using Kissinger method based on the differential thermal analysis data. The Tc value of the whiskers was found to be 94 K from M-T measurement. The magnetisation of whiskers before superconducting transition increased with decreasing temperature, and after superconducting transition, the magnetisation of whiskers decreased, from positive to negative, due to the diamagnetic nature of superconductivity. The change on magnetisation dependence of applied magnetic fields (M-H) showed that whiskers have paramagnetic-diamagnetic multiphase structure. © 2010 Institute of Materials, Minerals and Mining.
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    Study on the Physical and Electrical Properties of Bi2-?Zn?Sr2Ca2Cu 3O10+y Glass-Ceramic Superconductors
    (2002) Aksan M.A.; Yakmci M.E.; Balci Y.
    We have fabricated a series of glass-ceramic (Bi2-?Zn?) Sr2Ca2Cu3O10+y, where ? = 0.0, 0.2, 0.4, 0.6, 0.8, and 1.0, and investigated the effect of Zn ions on the glass formation, crystallization, thermal, electrical, and on the magnetic properties of the BSCCO-2223 superconductor system. The structural symmetry was found to be tetragonal in all the substitution levels. The best electrical performance was obtained from the ? = 0 sample, the Tc and Tzero was obtained at 110 K and 107 K, respectively. The Jc values of the samples were determined using the magnetization hysteresis and Bean's model. The crystallization kinetics were investigated using nonisothermal models of Augis-Bennett. The calculated activation energy, Ea, of the system was found to be in the range of 258-336 kJ/mol. ©2002 Plenum Publishing Corporation.