Abstract
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)}. The incommensurate modulation to the lattice (q approx. 0.39, 0, 0) appears to be caused by the sub-stoichiometry of copper. A DSC-study of the isostructural TlCu7-xS4 relates the thermal behaviour of the two thiocuprates to changes in the copper content. A tentative 'phase stability diagram' for such compounds is presented.
Original language | English |
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Pages (from-to) | 102-109 |
Number of pages | 8 |
Journal | Journal of Alloys and Compounds |
Volume | 288 |
Issue number | 1-2 |
DOIs | |
Publication status | Published - 1999 Jun 29 |
Externally published | Yes |