NMR in Chevrel-phase solid solution Mo_6Se_(8-x)Te_x

摘要

The Mo_6Se_8-Mo_6Te_8 solid solution was studied by X-ray diffraction, magnetic susceptibility and ~(77)Se and ~(125)Te NMR. Dynamic studies show that substitution occurs differently when Se replaces Te in Mo_6Te_8 than when Te replaces Se in Mo_6Se_8. Selenium first fills the high-symmetry sites and then it becomes statistically distributed on the 6f positions of the R3 symmetry. In the second case, Te occupies randomly the 8 X sites of the Mo_6X_8 structure, creating large perturbations of the ~(125)Te NMR spectra over the whole range of x.