Effect of oxygen pressure in the sintering process of YBa2Cu3O7−δ

The paper describes the electric and magnetic properties of high Tc oxide superconductor, YBa2Cu3O7-δ ceramics, and influence of the sintering oxygen pressure conditions. All specimens showed the super-conductivity sintered at 950°C, a various sintering oxygen pressure from 24.5 to 147 kPa. The magnetization (M) T c-end and T c-onset are found the maximum value at 73.6 kPa oxygen pressure, respectively. On the other hand, lattice constant of c-axis considerably decreases against oxygen pressure and obtained a minimum value at 74 kPa. This corresponds to the maximum of Tc and M constant maximum. It seems that the optimum amount of oxygen was obtained at this oxygen pressure. The average copper charge (ACC) was estimated there, as 2.32, which corresponds to oxygen composition of 7-δ = 6.98. The apparent density of ceramics is about 5.6 × 103 kg/m3, which is about 90% of the theoretical one.