Pressure Induced Self-Oxidation of [Formula presented]

Mössbauer spectroscopy, x-ray diffraction, and electrical resistance [[Formula presented]] studies in [Formula presented] to 40 GPa revealed an unforeseen process by which a gradual [Formula presented] oxidation takes place, starting at [Formula presented] reaching 70% [Formula presented] abundance at 40 GPa. The nonreversible process [Formula presented] occurs with no structural transition. The “ejected” electrons form a deep band within the high-pressure electronic manifold becoming weakly localized at [Formula presented]. This process is attributed to an effective ionization potential created by the pressure induced orientationally deformed (OH) dipoles and the unusual small binding energy of the valence electron in [Formula presented].