New High-Tc Superconductor Family of Cu-Based Cu1-xBa2Can-1CunO2n+4-δ with Tc>116 K

Publisher Website
Google Scholar
Abstract
A new high-temperature and nontoxic superconductor family of Cu 1-x Ba2Ca n-1 Cu n O2n+4-δ with critical temperature (T c)>116 K was discovered. These materials were prepared by the high-pressure technique. A superconductor sample with the highest T c contains mainly a Cu1- x Ba2Ca3Cu4O12-δ phase. The T c value of the Cu1- x Ba2Ca3Cu4O12-δ phase is 116.4 K. The phase has two kinds of tetragonal structures: body-centered tetragonal (bct) and simple tetragonal. The lattice parameters of bct are a=7.7114 Å and c=35.986 Å. The disordering or full occupation of Cu-vacancy sites leads to the simple tetragonal phase with the space group of P4/mmm and the half values of the lattice constants (a=3.8557 Å and c=17.993 Å) of the bct phase. The relationship between the lattice constant c and the number of CuO2 layers n is c/2=8.4+3.2(n-1) ( Å). The small CuO2-block spacing (8.4 Å) of this family suggests a lower anisotropy and higher J c than in Hg- and Tl-based superconductor families.