Single Crystal X-ray Diffraction Study of Cu-Based Superconductors

The crystal structures of Cu1−xBa2Can−1CunO2n+4−y were investigated by a single-crystal X-ray diffraction method. Single crystals (maximum size: 0.1 × 0.1 × 0.01 mm) of Cu-1234 (n=4) and Cu-1245 (n=5) phases have been synthesized using a high-temperature and high-pressure technique. The X-ray precession photographs showed the basic structures may be chosen as tetragonal primitive lattices; α = 3.8526(18) A, c = 17.973(5) A for Cu-1234, and α = 3.8577(5) A, c = 21.1546(14) A for Cu-1245, respectively. The weak superstructure spots, observed in the X-ray precession photographs in both compounds, can be explained by the micro-twin structures determined by electron diffraction.