Transport and structural properties of the Ho1Ba2Cu3O9 - delta superconductor

The compound Ho₁Ba₂Cu₃O_9-δ has been found to be a high T_c 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 Y₁Ba₂Cu₃O_9-δ compound but different from the K₂NiF₄ perovskite which is believed to be the superconducting phase for the La_2(1-x) Ba_2xCuO_4-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.