Enhancement in transition temperature and critical current density of CeO0.8F0.2FeAs by yttrium doping

We report significant enhancement in superconducting properties of yttrium substituted Ce1-xYxOFFeAs superconductors. The polycrystalline samples were prepared by two step solid state reaction technique. X-ray diffraction confirmed tetragonal ZrCuSiAs structure with decrease in both a and c lattice parameters on increasing yttrium substitution (with fixed F content). With smaller ion Y in place of Ce, the transition temperature increased by 6 K. Yttrium doping also lead to higher critical fields as well as stronger inter and intra-granular current density. The magnetization critical current density increased by an order of magnitude at 30 K and 1 T magnetic field.