Pressure-induced sharp coordination change in liquid germanate

The local structures around germanium in liquid germanate were studied using in situ x-ray absorption measurements up to 9GPa at 1273K. It was found that liquid germanate, consisting of tetrahedrally coordinated germanium, contracted with the increasing pressure without significant changes in the local structure up to 2.5 GPa, after which it showed an abrupt fourfold-to-sixfold coordination around 3 GPa. It was also found that the coordination change was completed below 4 GPa where upon a high density liquid consisting of octahedrally coordinated germanium became stable. It was also found that the GeO₆ octahedron in the high-density liquid was more compressible than that in solids.