EFFECT OF STARTING MATERIAL ON NORMAL-PRESSURE SYNTHESIS OF 124 SUPERCONDUCTOR Y1-XCAXBA2CU4O8

Successful synthesis of the 124 high-T-c superconductor Y1-xCaxBa2Cu4O 8 at ambient oxygen pressure is reported. A solid-state reaction techn ique using Cu(I)I instead of the conventional Cu(III)O in starting mat erials has been found to be effective for the normal oxygen-pressure s ynthesis of YBa2Cu4O8 as well as calcium-substituted Y1-xCaxBa2Cu4O8. It was found that careful attention must be paid in preparing high-qua lity Y1-xCaxBa2Cu4O8. The chemical state of the initial calcium compou nd was a critical factor in the successful synthesis of Y1-xCaxBaxCu4O 8 at ambient oxygen pressure. (C) 1998 Chapman & Hall.