A structural study of the quasi one-dimensional compound (Ca_1-xY_x)0.82CuO₂ prepared at room pressure

A solid solution of the quasi one-dimensional cuprate, (Ca_1-xY_x)0.82CuO₂ (0 ≤ × ≤ 0.435), has been successfully synthesized in an oxygen stream at room pressure. Structural changes have been determined for the basic crystal structure by means of the Rietveld method using powder X-ray diffraction. Upon Y doping, the nearest (intrachain) Cu-Cu distance increases from 1.93 to 1.98 Å, while the next-nearest (interchain) Cu-Cu distance decreases from 3.46 to 3.41 Å. The incommensurate superstructure, originating from differences in the periodic arrangement of the (Ca, Y) atoms and CuO₂ chains, has also been examined. The modulation period along the crystal a axis implies that the stoichiometry of the solid solution shifts toward that of the cation-deficient member (Ca_1-xY_x)0.80CuO₂. This compositional discrepancy might be canceled by the large change in the modulation period along the c axis.