Ultrahigh-Pressure Behavior of AO2 (A = Sn, Pb, Hf) Compounds

Rajkrishna Dutta, Boris Kiefer, Eran Greenberg, Vitali B. Prakapenka, Thomas S. Duffy

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6 Scopus citations


The high-pressure behavior of metal dioxides, AO2, is of wide interest due to their extensive polymorphism. In this study, high-pressure phase transitions in dioxides of selected group 4 and 14 elements (SnO2, PbO2, and HfO2) were examined by using in situ X-ray diffraction in the laser-heated diamond anvil cell to âˆ200 GPa and theoretical density functional theory calculations to 600 GPa. The cotunnite-type phase was found to be stable up to the maximum pressure in SnO2 and PbO2. For HfO2, a transition from the cotunnite to the Fe2P-type phase was observed in experiments at pressures >125 GPa, in agreement with our theoretical computations that predict a transition pressure of 111-137 GPa. Our calculations also predict a re-entrant cotunnite phase in HfO2 above 305-314 GPa that subsequently transforms into the Ni2In-type phase at 390-469 GPa. The transition sequences predicted in these oxides are consistent among three different exchange-correlation functionals and can be explained by the energetic competition of stationary electronic flat bands and a pressure-induced shift of electronic states to lower energies.

Original languageEnglish (US)
JournalJournal of Physical Chemistry C
StateAccepted/In press - 2019

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • General Energy
  • Physical and Theoretical Chemistry
  • Surfaces, Coatings and Films


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