High pressure induced coordination evolution in chain compound Li2CuO2

Using diamond anvil cell technique with angle dispersive X-ray diffraction (ADXD) of synchrotron radiation and electrical conductivity measurements, we have observed that CuO2 chain compound Li2CuO2 transforms from ambient orthorhombic symmetry into a new phase at above 5.4 GPa and room temperature. The new phase was found to be of monoclinic structure with an increased oxygen coordination number of Cu2+ from four at ambient to six at high pressure that provides a structural basis of the evolution of principle physical properties. The high pressure phase of Li2CuO2 is discussed in line with the first principle calculations.