Instability of the crystal lattice of YBa2Cu3O7-x, in the temperature region 240-200 K inferred from the data on Raman scattering of light
Rebane L. A., Fimberg T. A., Fefer E. M., Blumberg G. E., Ioon E.R.
A part of the lattice of a YBa2Cu307 _ x high-temperature superconductor was found to be unstable in the orthorhombic phase at temperatures in the range 240-200 K. At these temperatures a new band at 640 cm -1 can be seen in the Raman-scattering spectrum and there is an anomalous shift of the bands at 147, 340,432, and 501 cm ~1. The formation of metastable Cu06 complexes accounts for the lattice instability.