Local structure of the defective oxide selenides Ba2Cu1-xO2-yCu2Se2

This is a proposal to examine the highly defective CuO2 planes in the layered oxide selenides Ba2Cu1-xO2-yCu2Se2 using neutron total scattering measurements to provide insight into how the CuO2 planes have fragmented, to determine the the local structure of the Cu ions (e.g. linear O-Cu-O units vs CuO4 square planes, and to enable assignment of the oxidation states. Neutron PDF measurements are essential for this problem as they will enable O to make a significant contribution to the scattering.