Superionic State in Alumina Produced by Nonthermal Melting

Density functional–based molecular dynamics reveals a transient superionic state in Al2O3 produced by nonthermal phase transition under extreme electronic excitation. At electronic temperatures above Te ≈ 2.75 eV, the oxygen sublattice exhibits fluid behavior, whereas the aluminum sublattice is in a...

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Bibliographic Details
Published in:Physica status solidi. PSS-RRL. Rapid research letters 2020-03, Vol.14 (3), p.n/a
Main Authors: Voronkov, Roman A., Medvedev, Nikita, Volkov, Alexander E.
Format: Article
Language:English
Subjects:
ab initio calculations
Aluminum
Aluminum oxide
Molecular dynamics
nonthermal melting
Phase transitions
Subsystems
superionic states
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Summary:Density functional–based molecular dynamics reveals a transient superionic state in Al2O3 produced by nonthermal phase transition under extreme electronic excitation. At electronic temperatures above Te ≈ 2.75 eV, the oxygen sublattice exhibits fluid behavior, whereas the aluminum sublattice is in a solid state. This state exists up to Te ≈ 3.25 eV, where Al2O3 turns metallic–superionic; at Te ≈ 3.75 eV, the aluminum sublattice disorders. Quenching the superionic state under pressure >400 GPa freezes it into a metastable mixed amorphous–crystalline phase where the oxygen subsystem is disordered solid, whereas the aluminum one is ordered. Ab initio simulations uncover the nonthermal transition of Al2O3 into superionic state with liquid oxygen sublattice and the solid aluminum one at electronic temperatures from Te ≈ 2.75 to 3.75 eV. The semiconducting phase turns metallic at Te > 3.25 eV. Pressure above ≈400 GPa stabilizes this state, resulting in a metastable mixed amorphous–crystalline phase.
ISSN:1862-6254
1862-6270
DOI:10.1002/pssr.201900641