Pressure-induced splitting and buckling of Cu-O chains in the low-dimensional structure of SrCuO2

A pressure-induced splitting of the Cu-O chains was found in SrCuO2 at pressures >7 GPa and room temperature. The high-pressure phase is a superstructure of the infinite-layered tetragonal superconducting phase of SrCuO2 and is not stable under ambient conditions. The Cu-O chains buckle with further increasing pressure, and a new high-density polymorph of SrCuO2 is formed at 34.2 GPa.