X-ray diffraction study of the incommensurate structure in Bi_2.2Sr_1.8CaCu₂O_8+xsingle crystals

Abstract

High-resolution X-ray diffraction measurements have been performed on single-crystal samples of Bi2.2Sr1.8CaCu2O8+x at 300 K. It was shown that the symmetry of crystals is lower than orthorhombic. In the vicinity of the odd 00l (l=2n+1) reciprocal-lattice points, incommensurate satellites corresponding to a modulation wavevector q=-0.021b*+0.01c* with strong asymmetry of superlattice intensities were observed. Asymmetrical arrangements of incommensurate S peaks with the modulation wavevectors q1=-0.225b*+0.061c* and q2=0.193b*+0.078c* were also observed. The results obtained are discussed.