SYNTHESIS AND IRREVERSIBILITY OF OXYGEN WEIGHT-LOSS IN 80-K YBA2CU4O8SUPERCONDUCTOR

Synthesis of YBa2Cu4O8 superconductor usually requires oxygen pressure greater than 20 MPa and very long heating schedules at high temperatu res. Here we report synthesis of YBa2Cu4O8 superconductor by the stand ard solid-state reaction between the precursors BaCu2O3 and Y2O3 in th e presence of alkali nitrate, NaNO3, under ambient O2 pressure. The re sulting sample showed zero resistance at 78 K. The presence of 124 was confirmed by high-resolution X-ray diffraction studies. Irreversibili ty of oxygen weight loss was studied by thermogravimetric analysis and differential thermal analysis.