On the first incommensurate ordering of NH4Cu7-xS4
The first incommensurate ordering of NH4Cu7-xS4 (x = 0.16) has been investigated using X-ray single crystal diffraction at 174 K. The modulated structure is described with monoclinic symmetry with the cell parameters a = 10.272 (angstrom), b = 10.272 (angstrom), c = 7.694 (angstrom) and β=90.0°. It belongs to the four-dimensional space group P:P2/n:-11 {conventional setting P:P2/b:-11 (no. 13.1)}.
