Superspace group description of modulated composite crystal (Sr2Cu2O3)(0.70)CuO2, "Sr14Cu24O41" with two-legged ladder and 1D chain

The modulated structure of single composite crystal, (Sr2Cu2O3)(0.70)CuO2, "Sr14Cu24O41" with two-legged Cu2O3 ladder and one dimensional CuO2 chain h as been investigated by means of the X-ray diffraction method and (3+1)-dim ensional superspace group approach. The model of the modulated composite st ructure of (Sr2Cu2O3)(0.70)CuO2 with centrosymmetric superspace group has b een compared with the model with acentric superspace group. By considering all of the Sr-O lengths and the magnitude of their modulation amplitudes, i t has been deduced that the atomic modulation waves with centrosymmetric sy mmetry are more significant for the modulated structure of (Sr2Cu2O3)(0.70) CuO2 than the waves with acentric symmetry. (C) 2001 Elsevier Science B.V. All rights reserved.