Özet:
This work is related to the structural, superconducting, and transport properties of the compounds Y3Ba5Cu8O18 and Y3Ba5Ca2Cu8O18 prepared by the sol-gel method. The influence of the doping of Ca atoms into the compound Y3Ba5Cu8O18 was studied by employing XRD, SEM, AFM, EDX, DTA, TGA, and the electrical resistivity (rho), Hall coefficient (R (H)), Hall mobility (mu (H)), and magnetoresistance measurements. The XRD spectra showed that Y3Ba5Ca2Cu8O18 almost has the same crystal structure as that of Y3Ba5Cu8O18, except with some impurity peaks. The resistivity measurements have pointed out that the compounds Y3Ba5Cu8O18 and Y3Ba5Ca2Cu8O18 have their T (c)-onset temperatures at approximately 92.7 and 86.6 K, respectively. The Hall coefficients R (H) and Hall mobilities mu (H) have been measured at the 10-300 K temperature interval in a magnetic field of 0.55 T. The signs of R (H) and mu (H) are found to be positive for both samples, which indicate that the conduction is p-type in our samples. As expected, the magnetoresistance results clearly demonstrate a considerable decrease of the offset temperatures with increasing magnetic field.
