| Summary: In this study, superconducting YxLu1-xBa2Cu3O7-δ samples (x=0 and x=0.5) were prepared by the MPMG method using five different sintering temperature as 920, 930, 940, 960, 985oC. The structural properties of the samples were studied by XRD analysis. Magnetic properties of the samples were investigated by the measurements of magnetic levitation force in both zero field cooling (ZFC) process and field cooling (FC) process in liquid nitrogen temperature (77K). Further investigations on magnetic behaviour of the samples were carried out by magnetization measurements using VSM option of a Quantum Design PPMS. The field dependence of critical current density for the samples studied were estimated from isothermal M-H hysteresis curves measured at various selected temperatures (10, 20, 77K). The highest critical current density was obtained for the Lutesium doped sample grown at 940 oC. Both magnetic levitation force measurement and M-H loop measurement showed that as the sintering temperature increases from 920 to 985 oC, the critical current density increases. Finally, the magnetic relaxation rate was obtained by measuring the time decay of the remnant magnetization for about 180 s. Since magnetic relaxation has logarithmic time dependence, we can determine the activation energy. As an example, the activation energy for the sample having highest critical current density was found to be 75 meV at 20 K in the remnant magnetization regime upon exerting high enough magnetic field.
Anahtar Kelimeler: YBCO, Lutetium Doping, MPMG Method, Magnetic Levitation Force, M-H Hysteresis, Critical Current Density, Magnetic Relaxation.
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