Intergrowth of structures in the Tl–Ba–Ca–Cu–O system

Abstract

Three intergrowth phases between the high- T c superconducting cuprates TlBa 2Ca 2Cu 3O y (Tl-1223) and Tl 2Ba 2Ca 2Cu 3O y (Tl-2223) have been detected and identified in a non-equilibrium sample with composition Tl 1.05Ba 2Ca 2Cu 3O y . Complete structure models including space group, cell parameters and atom coordinates are derived for quantitative analysis. X-Ray diffraction, AC susceptibility and scanning electron microscopy experiments show that these intermediate phases have a long range order. The results are discussed in the light of the formation path for Tl-1223 whose final step is the transformation from Tl-2223 to Tl-1223.