Investigation of structural and physical properties of Yba2Cu3--xRexOy(x=0, 0,3, 0,5, 0,7, and 1,0 ve Re=Yb, Sm, Nd) superconductors

SUMMARY Investigategation of Structural and Physical Properties of YBa2Cu3-xRexOy (x=0, 0.3, 0.5, 0.7, 1.0 and Re=Yb, Sm, Nd) Superconductors In this work, sample production in the form of YBa2Cu3.xRexOy (Re=Yb, Sm, Nd) has been carried out by using solid state reaction (x=0, 0.3, 0.5) and Flame-Quench-Melt Growth (FQMG) (x=0, 0.3, 0.5, 0.7, 1.0) techniques. Some structural and physical properties of the samples prepared by two methods have been investigated using x-ray diffraction (XRD), SEM/optical micrographs, magnetic levitation force, resistivity and finaly AC susceptibility measurements. Therefore, it was found that the substitution of above elements did not enter into the unit cells of the samples prepared by solid state reaction method and the superconducting properties of all samples were destroyed with increasing the content of substitution in samples. For the samples prepared with FQMG method, the substitutions mentioned above were observed to enter into the unit cell of the samples, thus, it was observed that the substitution of x=0.3 Yb and x=0.3 Nd improved some superconducting properties of the samples. The maximum value of the magnetic levitation force, measured at liquid nitrogen temperature, on the x=0.3 Yb sample is found to be ~%240 greater than that of the pure sample. Critical current density of x=0.3 Nd calculated using the Bean model is found to be ~%235 greater than that of pure sample. Critical current densities as a function of the magnetic field are calculated by developed a simple method based on magnetic levitation force measurement data. Comparision of critical current densities obtained from levitation force and calculated theoretically from AC susceptibility measurement data, for the same temperature and field strength, showed that the values obtained from AC susceptibility measurements are greater. It was attributed to the amounts of precipitations in samples. Key Words: Superconductor, Solid State Method, FQMG Method, Yb, Sm, Nd Adding, Magnetic Levitatin Force, Critical Current Density, Bean Model. VI