DISTRIBUTION OF THE SATELLITE REFLECTIONS OF THE MODULATION AND ITS THERMAL-STABILITY IN SINGLE-CRYSTAL BI2SR2CACU2OY

The satellite distribution around the main reflections of the incommen surate modulation in Bi2Sr2CaCu2Oy has been studied by means of x-ray diffraction on a number of single crystals. The presence of the forbid den reflections which are incompatible with a B-centered Bravais latti ce is found to be correlated with the spread of the mosaic blocks in t he crystal sheet and therefore spurious to the distribution of the sat ellite reflections in the reciprocal space. Diffraction data collected for a highly oriented crystal annealed in flowing nitrogen at 650-deg rees-C for 60 h have shown that the structural modulation,is coherent with the Bi2Sr2CaCu2Oy Phase and robust to the anneal. Relationships b etween superconductivity, structural modulation, and oxygen content in the compound are discussed.