Investigation of electrical and magnetic properties of Y1Ba2Cu3+X O7+d superconductors

Abstract

The electrical and magnetic properties of YIBa2Cu3+xO~samples were studied from room temperature down to liquid nitrogen temperature. Samples were prepared by standard solid state reaction technique. The DC resistance was measured by using four-point probe method. The transition temperature Tc was determined from AC, DC resistance and AC susceptibility measurements. The structural homogeneity of the samples were checked by X-ray diffraction (XRD). XRD patterns show. that the samples were orthorhombic and single phase. The oxygen content in the samples has been estimated by idometric technique. The oxidation states of these samples were found to increase with increasing copper content. The oxidation state for the sample Y -123 was found Y1Ba2Cu30668 where as the oxidation state for Y-124 was Y1Ba2Cu40781 DC resistance measurement for Y-123 sample with x = 0 showed a sharp superconducting transition having an onset temperature of about 91 K. Though the signal from AC susceptibility measurement was weak, it was observed that Tc decreases as copper content increases in Y1Ba2Cu3+x07+6samples. The AC resistance measurement also showed that the transition temperature Tc decreases as the copper concentration in the sample increases. The Y-124 sample is a suppression of a second order phase transition (orthorhombic to tetragonal), a well-known characteristic feature of the .Y-123 superconductors. The stable oxygen content in Y-124 makes its structure thermodynamically more stable than Y-123 and as a result no oxygen vacancies or twin structures are present in the Y-124 system.