Abstract
We report the observation of bulk superconductivity in PrBa2Cu3Ox single crystals for the first time. These samples were grown by the travelling-solvent floating-zone (TSFZ) method in oxygen-reduced atmosphere. The as-grown crystal has a longer c-axis lattice constant an than any values previously reported for oxygen-reduced PrBa2Cu3Ox. After oxygen annealing, resistivity becomes zero below T=80 K, and zero-field-cooled magnetization shows diamagnetism with full volume fraction. X-ray energy dispersion spectrum and X-ray diffraction analyses show that this superconducting phase is orthorhombic PrBa2Cu3Ox.