STRUCTURAL-CHANGES IN LANTHANIDE DOPED YBA2CU4O8

The structural changes induced by substitution of several lanthanides (Ln = Lu, Tb, Gd, Pr and Ce) for Y in the high-T-c superconductor YBa2 Cu4O8 have been studied by neutron powder diffraction. A series of sam ples with varying contents of Lu and Gd was prepared. Codoping with Sr was observed to increase the solubility of Lu. A drastic depression o f T-c is observed for Ce doped Y-124 due to hole filling that is not c ompensated by charge transfer from the double CuO chains.