HGO AS AN INTERNAL OXYGEN SOURCE IN Y1BA2CU3O7-DELTA

This paper reports an alternative technique for preparing Y1Ba2Cu3O7-d elta with uniform oxygen stoichiometry which eliminates the need for f lowing oxygen during sintering. Our studies show that when HgO is adde d to the YBaCuO system it provides an abundant source of oxygen during sintering. Mercury diffuses out of the system leaving the crystal str ucture intact. We have thus been able to obtain a T-c (zero resistivit y) of 90 K consistently in HgO doped YBaCuO specimens and sintered in air. An optimum value of HgO leads to a strongly coupled grain materia l. Resistivity, X-ray fluorescence (XRF), X-ray diffraction (XRD), sca nning electron microscopy (SEM) and a.c. susceptibility data are repor ted.