Abstract
The melt-quenched products of the orthorhombic YBa2Ca3O7-δ compound from 1200° and 1400°C were characterized by X-ray powder diffraction and DTA-TG methods. It was found that crystalline phases in the quenched samples from 1200°C were Y2BaCuO5 (major phase) and BaCuO2, while those in the quenched samples from 1400°C were Y2O3 (major phase) and BaCuO2. The products showed the weight gain and the exothermic peaks in the range of 200° to 300°C, corresponding to the oxidation of Cu(I) in BaCuO2-x and amorphous compounds to Cu(II), and the endothermic peaks due to the partially melting in the range of 900° to 950°C. In addition, it was confirmed that superconducting YBa2Cu3O7-δ compound began to form by annealing the melt-quenched products at 900°C.
