Structural Variations on Superconductor Tl-Ba-Ca-Cu-O Oxides

Abstract
Two crystal structures for c 105 K Tl-Ca-Ba-Cu-O oxides, with lattice parameters a=b=5.44 Å, c=29.32 Å, and a=b=5.44 Å, c=35.68 Å, isostructural with Bi2CaSr2Cu2O8+x and Bi2Ca2Sr2Cu3O10+x , respectively, were found by electron microscopic observation. The stacking arrangements for the CuO2-Ca-CuO2 slabs and BaO-TlO-BaO slabs in their structures result in a series of phases and stacking disorder in this oxide system. Weak long-range-order, taking place in the BaO-TlO-TlO-BaO slabs in the a-c plane projection, was observed.