Discovery of zirconium dioxides for the design of better oxygen-ion conductors using efficient algorithms beyond data mining

Abstract

It is important to find crystal structures with low formation (E v ) and migration-barrier (E m ) energies for oxygen vacancies for the development of fast oxygen-ion conductors. To identify crystal structures with lower E v and E m than those of ground-state ZrO 2 , we first reoptimize the crystal structures of various oxides reported in the database, and then directly construct them using an evolutionary algorithm. For efficient searching, we employ the linearized ridge regression model for E v using descriptors obtained from density functional theory calculations of the unit cells and apply the predicted E v as a fitness value in the evolutionary algorithm. We also find a correlation between the E v and E m for the crystal structures of ZrO 2 . On the basis of this correlation, we confirm that the newly constructed crystal structures, as well as certain reoptimized structures from the database, that possess low E v also have E m lower than that of ground-state ZrO 2 . Our successful strategy consisting of a combination of the evolutionary algorithm, first-principles calculations, and machine-learning techniques may be applicable to other oxide systems in finding crystal structures with low E v and E m .

[Retracted] An Analysis of the Effects of the English Language and Literature on Students’ Language Ability from a Multidimensional Environment

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Oxygen conduction mechanism in Ca3Fe2Ge3O12 garnet-type oxide

“…We also computed E form and E mig as their low values are favorable for a higher σ O 40,41 . The E form values were computed using the conventional cubic cell (160 atoms with a lattice constant larger than 10 Å) 22 :where E (Ca 3 Fe 2 Ge 3 O 12 : D q ) is the energy of a supercell including a point defect ( V O or O i ), E (Ca 3 Fe 2 Ge 3 O 12 ) is the energy of a supercell of the perfect Ca 3 Fe 2 Ge 3 O 12 , n D is 1 (or −1), which corresponds to the interstitial defect (or vacancy), μ O is the chemical potential of an added (or removed) O, q is the charge of the point defect, E HOMO is the eigenvalue of the HOMO formed mainly by O 2 p , E Fermi is the Fermi level as a variable, and Δ E LZ is the correction term proposed by Lany and Zunger 42,43 to compensate the image charge interactions between supercells for the charged point defect.…”

First-principles prediction of high oxygen-ion conductivity in trilanthanide gallates Ln3GaO6

“…We also computed E v and E m because their low values are favorable for achieving a higher σ O [31,32]. The E v values were computed using the supercell method [33] as follows:…”