Abstract
We present Raman and infrared absorption data for with 7>x>6 for several samples with well-characterized oxygen content. Over this range the material has an oxygen-deficient tripled perovskite structure whose superconductivity properties depend critically on x. An orthorhombic-to-tetragonal transition occurs for x≊6.5. We have examined both phases for the frequency range ω>400 which contains the Cu-O bond-stretching vibrations. A force-constant model has been developed which allows us to assign the features in the spectra. Our results are consistent with the linear Cu-O-Cu-O chains in being absent in the nonsuperconducting .
- Received 11 May 1987
DOI:https://doi.org/10.1103/PhysRevB.36.850
©1987 American Physical Society