Transport and structural properties of the Ho1Ba2Cu3O9-δ superconductor

The compound Ho1Ba2Cu3O9−δ has been found to be a high Tc superconductor. The onset of the superconducting transition is 88 K with zero resistance achieved at 87 K. The x-ray diffraction spectrum of this material shows it to be a single-phase perovskite similar to the Y1Ba2Cu3O9−δ compound but different from the K2NiF4 perovskite which is believed to be the superconducting phase for the La2(1−x) Ba2xCuO4−δ system. Possible oxygen deficiencies in several of the unit cell planes are discussed. The room-temperature resistance, the superconducting onset temperature, and the emergence of the single phase all depend upon the sample preparation firing conditions.