Amorphization of cuprite, Cu2O, due to chemical decomposition under high pressure

Using synchrotron radiation and a diamond-anvil cell, a structural study of the phase transformations in Cu2O is carried out from diffraction data obtained in situ while heating at a pressure of 30 GPa. Around 140°C, we observe a transition of Cu2O to an amorphous state, with the amorphous state persisting to about 260°C. Further heating up to 400°C yields at first a nanocrystalline two-phase mixture of Cu+CuO and, then, with prolonged heating at 400°C, full crystallization of this mixture. The present structural data are the first experimental evidence of solid-state amorphization under high pressure as an intermediate stage of the high-pressure decomposition of complex compounds.