Ce-katkılı BI-2212?nin bazı fiziksel özelliklerinin incelenmesi

In this study, the structural and superconducting properties of compounds prepared by doping Cerium to Bi?2212 system in the form of Bi2Sr2Ca1Cu2CexOy (x=0, 0.001, 0.003, 0.005, 0.01, 0.03, 0.05, 0.1) were investigated. All samples were prepared using the standard solid-state reaction method. In order to make comparison with the pure sample (x=0), all samples were prepared under the same conditions. While the structural characterization of all samples were carried out with X?Ray Diffraction(XRD) and Scanning Electron Microscopy(SEM) measurements, electrical and superconducting properties of the samples were performed via resistivity measurements. Based on the results of resistivity measurements of the samples done in the case of magnetic field, as it was observed that the critical onset temperature(Tconset) increased with increase in Cerium addition until 0.05 above which the onset point of the sample rapidly started to decrease. However, the critical offset temperature(Tcoffset) was found to decrease with increasing Cerium concentration and applied magnetic field. Besides, it was noticed that all samples showed metallic behaviour above Tconset temperature. Moreover, the resistivity (at room temperature) was also observed to increase with the increase in the addition of the Cerium atoms. As for XRD measurements, all lattice parameters and phases corresponding to peaks on X-ray diffraction graphs were determined by means of literature. Furthermore, volume fractions of Bi?2223 and Bi?2212 phases were calculated for all samples. It was clearly found that the fraction of Bi?2212 phase was greater than the fraction of Bi?2223 phase. However, the volume fraction of Bi?2223 phase increased up to an optimum concentration value(x=0.05). As it is well known the critical onset temperature(Tconset) of a sample increases with the increase in the Bi?2223 volume fraction. This situation was also observed at resistivity measurements. Therefore, we can clearly say that XRD measurements are found to be in good agreement with resistivity measurements. Moreover, surface morphology and grain connectivity of the samples were obtained to degrade with increase in the Cerium addition from SEM investigations. To sum up, Cerium addition was found to supress the superconducting properties.