Abstract
High-energy x-ray diffraction is used to investigate the bulk oxygen-ordering properties of Four different superstructures of Cu-O chains aligned along the b axis and ordered with periodicity along the a axis have been observed. For the only observed superstructure is ortho-II with At room temperature, we find ortho-III for ortho-V in a mixed state with ortho-II at and ortho-VIII at Ortho-II is a three-dimensional ordered structural phase, the remaining ones are essentially two-dimensional. None of the superstructures develops long-range ordering. The temperature dependence of the observed superstructure ordering is investigated explicitly and a structural phase diagram is presented.
- Received 9 January 2003
DOI:https://doi.org/10.1103/PhysRevB.68.104515
©2003 American Physical Society