HIGH-PRESSURE SYNTHESIS OF SUPERCONDUCTING (BA1-XSRX)2CU1+YO2+2Y+DELTA(CO3)1-Y(0.35-LESS-THAN-OR-EQUAL-TO-X-LESS-THAN-OR-EQUAL-TO-0.6,Y-APPROXIMATE-TO-0.1)

A new copper-oxide superconductor containing carbon (Ba1-xSrx)2Cu1+xO2+2y+delta(CO3)1-y (0.35 less-than-or-equal-to x less-than-or-equal-to 0.6, y almost-equal-to 0.1), which is structurally related to Sr2CuO2CO3, was synthesized under high oxygen pressures of more than 5 atm. The onset temperature for superconduction T(c)(onset) increased with oxygen partial pressure (P(O2)) during synthesis. Optimum P(O2) was about 50 atm and (Ba0.55Sr0.45)2Cu1.1O2.2+delta(CO3)0.9 synthesized under 50 atm O2, showed a T(c)(onset) of about 40 K and a T(c)(zero) of about 26 K.