(a, b) Three-dimensional distributions of diffraction intensities of η′-Cu3+x(Si,Ge) in reciprocal space. (a) A projection along a*–b*, with the basic unit cell and modulation vectors indicated. (b) Three layers viewed along c*. (c) The structure in the supercell approximation, showing one slab of Cu clusters and one layer of Si/Ge atoms. Reprinted (adapted) with permission from Palatinus et al. (2011). Copyright (2011) the American Chemical Society.