New High-Tc Superconductor Ag1-xCuxBa2Can-1CunO2n+3-δ Family with Tc> 117 K

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Abstract
A new high-temperature and nontoxic superconductor Ag1- x Cu x Ba2Ca n -1Cu n O2 n +3-δ family with T c>117 K was discovered. These materials are prepared by the high-pressure technique. A superconductor sample with the highest T c contains mainly a Ag1- x Cu x Ba2Ca3Cu4O11-δ (x=0.75) phase. The phase has a body-centered tetragonal structure with lattice constants of a=7.7270 Å and c=36.222 Å. The disordering of Ag sites leads to the space group of P4/mmm and the lattice constants of a=3.8635 Å and c=18.111 Å. The T c value of the Ag1- x Cu x Ba2Ca3Cu4O11-δ phase is 117.1 K. The relationship between the lattice constant c and the number of CuO2 layers n is c/2=5.3+3.2n ( Å). The small CuO2-block spacing (8.5 Å) of this family suggests a lower anisotropy and higher J c than Hg- and Tl-based superconductor families.