NEUTRON STRUCTURAL STUDY ON Y0.8CA0.1CE0.1BA2CU4O8 SUPERCONDUCTOR

The structure of Y0.8Ca0.1Ce0.1Ba2Cu4O8 (T-C = 63 K) has been investig ated using powder neutron diffraction in order to assess the influence of the bridging Cu(2)-O(4) and Cu(1)-O(4) bonds on the superconductin g transition temperature of 124-phase. The compound exhibits full occu pancy at Y- and Ba-sites. The cell parameters, site occupancies, inter atomic distances and bond angles are in general agreement with the mos t homogeneous 80 K sample YBa2.2Cu4O8. However, there is a significant reduction in the puckering of Cu(2)-O(2)/O(3) planes, a movement of O (4) towards Cu(2) and a shorter Cu(2)Cu(2) distance. Annealing the tit le sample in flowing argon depressed T-C, and depleted the oxygen cont ent as well as Y-site occupancies.