Investigation of the microstructure and superconductivity properties of RE358 (RE=Y, Nd, Sm, Eu, Gd, Dy, Ho, Er) high temperature superconductors

In this study; the compound RE3Ba5Cu8O7-δ abbreviated as RE358 (RE=Y, Nd, Sm, Eu, Gd, Dy, Ho, Er) rare earth (RE) high temperature superconductors were produced by the Melting-Orientation-Growth method, using the melting temperatures determined according to the DTA and TGA analysis results of the sintered samples. X-ray diffraction (XRD) analyses were performed on Y358 samples and it was observed that the structure were consistent with the literature. The microstructures of these samples were examined using polarized light microscopy. The grain sizes of (Y2BaCuO5) named Y211and the states of non-superconducting phases were examined from surface images. The magnetic levitation forces of the samples were measured as a function of distance. Levitation force hysteresis curves and maximum repulsive-attractive forces were determined. The superconductivity transition temperatures of the samples were determined by performing temperature dependent resistivity measurements. For R358 samples produced with rear earth elements other than Y and Sm, it was observed that the number of RE211 non-superconducting particles decreased and their grain sizes became smaller, leading to a more homogeneous distribution. In addition to, the magnetic levitation force and current density declined slightly, and the superconductivity transition temperature dropped by 1 - 7 K.