ON THE HIGH Tc SUPERCONDUCITVITY OF Y-Ba-Cu OXIDE

The supercoductivity and structure of Y-Ba-Cu oxide have been investigated by means of electrical resistance and magnetic susceptibility measurements as well as X-ray diffraction, SEM and electron probe microanalysis. The results show that the onset temperature is 107.6K and the zero resistivity state occures at 94.8K with a width of about 2K for the sample of Ba_3Y_2Cu_5O_(5(3-z)). Diamagnetic susceptibility (Meissncr effect)was observed by magnetic susceptibility measurement, and confirmed with electrical resistance determination. The specimen consists mainly of hexagonal (or rhombohedral) ABO_3-type phase with lattice parameter of a=b=0.550nm, c=1.332nm and space group of R3c of R3m. The particles of oxide well connecte up each other, although quite a large number of pores exist. Zero resistance can be kept while up to 2A/cm~2 current passes through the sample.