HIGH T_c SUPERCONDUCTOR YBa_2 Cu_3 O_x SYNTHESIZED BY UNIDIRECTIONAL REACTION

A unidirectional reaction for synthesis of the high T_c superconductor YBa_2Cu_3O_x has beenproposed, Its T_c is 90-94.5 K and △T is 1 K. The phase relationships in the systemY_2BaCuO_5-Y_2Cu_2O_5-CuO-YBa_2Cu_3O_x were studied and discussed.