Modeling of the magnetization-temperature change of YBCO (358)superconductor in critical state framework

In this thesis, YBCO (358) superconductor has been investigated by means of magnetic moment-temperature measurements and theoretical analysis. Magnetic moment-temperature curves were evaluated for the dependence of oxygen ratio during sintering. From the examinations of the experimental results of the samples, the change of oxygen ratio was seen to change the pattern of moment-temperature curves. Experimental results are qualitatively discussed in the framework of the critical state model. The variation of the critical current density values from 50 to 100 and zero, caused the change in oxygen ratio from zero percent to 50% and 100 %, respectively. The field and temperature dependence of the critical current density for each sample were determined from the theoretical and experimental best-fit curves. Best fit curves were obtained for M-T data and the used parametric values were compared for each sample. It was seen that the results were consistent with the literature.