Neutron diffraction studies of GeCuO3

Crystal structure of CuGeO3, which has been reported to undergo a spin-Peierls transition at 14 K, has been determined by neutron powder diffraction at 300, 20 and 4.2 K. The structure has been refined in the space group Pmma, ie without displacement of the Cu atoms from a one-dimensional chain. Anisotropic broadening of (h01) reflections, observed in all three sets, is modelled bu an orthorhombic micro-strain along a and c, perpendicular to the Cu-Cu chains.