A NEW 1212-TYPE PHASE: Cr-SUBSTITUTED TlSr2CaCu2O7 WITH Tc UP TO ABOUT 110 K

Superconductivity up to about 110 K in the CrTlSrCaCuO system was observed by resistance and ac susceptibility measurements. Powder X-ray diffraction analyses showed that a 1212-type phase, Cr-substituted TlSr2CaCu2O7, is responsible for the observed superconductivity. This is the first time that single-element substitution for TlSr2CaCu2O7 increases Tc of the 1212 phase to above 100 K. The Cr-substituted TlSr2CaCu2O7 is easily prepared and has very good quality suitable for practical applications.