Reverse Monte Carlo analysis of the local order in liquid Ge0.15Te0.85 alloys combining neutron scattering and x-ray absorption spectroscopy -: art. no. 174209

The structure of liquid Ge0.15Te0.85 alloys that exhibit a density anomaly between 633 K and 733 K at ambient pressure was investigated using x-ray absorption spectroscopy at the Ge K edge. Using a reverse Monte Carlo method to combine the present results with neutron scattering data, we show that the volume contraction is associated with an increase of the first neighbor coordination number around both Ge and Te by about one atom. The coordination number of Ge increases from 3 +/- 0.3 to 4.1 +/- 0.3. These results support an interpretation of the density anomaly in terms of the same Peierls-like distortion mechanism acting in the liquid state and in the neighboring (pure Te and GeTe compound) phases.