Identification of superconducting phases in a new structural series TlBa2Can-1CunO2n+(3-x)by transmission electron microscopy

Abstract
Two phases have been identified in the multiphase compounds of TlBaCaCuOx with a superconducting temperature of 72.5 K. Both phases are weakly modulated incommensurately in the (100) and (010) directions. Their basic lattices are tetragonal, with space group P4/mmm and lattice parameters of a=0.387 nm, c=1.29 nm and a=0.387 nm, c=0.99 nm. These two phases and the recently reported TlBa2Ca2Cu3Ox are members of a new structural series TlBa2Can-1CunO2n+(3-x).