Synthesizing, characterizing and investigating the crystal structural, electric and magnetic properties of superconducting compound Y2Ba5Cu7Ox

A new superconductor, Y2Ba5Cu7Ox , (Y257), a member of YBCO family, was synthesized using the standard solid-state reaction method. The powder was calcinated in the air flow and then in the next step the sample was sintered in the presence of oxygen flow. The unit cell of the compound includes the subsequent block of Y123, Y124 and an excess BaO layer which are set in the c direction. The structural properties and space group of the compound were studied using the X-ray diffraction experiment which is analyzed by Rietveld method. The electric resistivity of the sample showed a transition to a superconducting state at onset superconducting transition temperature 98 K and reached to zero resistivity at offset superconducting transition temperature 92 K. In normal state, from the room temperature down to the onset superconducting transition temperature, the electric resistivity shows a metallic behavior. In the measurement of resistivity versus temperature in the presence of magnetic field, the resistivity decreases to zero with a slower rate at higher magnetic fields and shows a broadening behavior. Applying the magnetic field leads to the broadening of the superconducting transition region and decreases the offset superconducting transition temperature. The experimental resistivity data satisfies the thermally activated flux creep model.