Lattice dynamics and superionic transition in ceria from first principles
ORAL
Abstract
We show how lattice dynamics in high-temperature ceria, CeO2, can be studied beyond the quasiharmonic approximation [1]. The results indicate that the previously proposed precursor for the transition to the superionic phase is an artifact of the failure of the quasiharmonic approximation. We further directly observe the superionic transition at high temperatures [2] in our ab initio molecular dynamics simulations and find that it is initiated by the formation of oxygen Frenkel pairs. The Frenkel pairs are shown to form in a collective process involving simultaneous motion of two oxygen ions.
[1] J. Klarbring, N. V. Skorodumova, and S. I. Simak, Phys. Rev. B 97, 104309 (2018).
[2] J. Klarbring and S.I. Simak, Phys. Rev. Lett. (2018), accepted.
[1] J. Klarbring, N. V. Skorodumova, and S. I. Simak, Phys. Rev. B 97, 104309 (2018).
[2] J. Klarbring and S.I. Simak, Phys. Rev. Lett. (2018), accepted.
*The support from Swedish Research Council (VR) (Project No. 2014-4750) and the Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University (Faculty Grant SFO-Mat-LiU No. 2009 00971) are acknowledged. The computations were performed on resources provided by the Swedish National Infrastructure for Computing (SNIC) at the PDC Centre for High Performance Computing (PDC-HPC), the National Supercomputer Center (NSC).
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Presenters
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Sergei Simak
- Linkoping University