Cubic new compound in the Ba-Ca-Cu-O system: Preliminary phase relationships.

摘要

We have identified a new compound in the Ba-Ca-Cu-O phase diagram with a composition close to Ba(sub 4)CaCu(sub 3)O(sub x). Single-crystal x-ray diffraction reveals that is phase crystallizes in an ordered cell based on a cubic perovskite framework, but with doubled unit cell constants. The compound, which is not superconducting, has also been characterized via powder x-ray and neutron diffraction. In addition, we report some preliminary tie-line relationships to and near Ba(sub 4)CaCu(sub 3)O(sub x) in the Ba-Ca-Cu-O phase diagram and reactions of Ba(sub 4)CaCu(sub 3)O(sub x) with Tl(sub 2)O(sub 3). 5 refs., 2 figs.