Insight into Design of Improved Oxide Ion Conductors: Dynamics and Conduction Mechanisms in the Bi_0.913V_0.087O_1.587 Solid Electrolyte

Abstract

Extensive quasielastic neutron scattering measurements have been used to directly observe oxide ion dynamics on the nanosecond time scale in bismuth vanadate with formula Bi0.913V0.087O1.587, which exhibits remarkable oxide ion conductivity at low temperatures. This is the longest time scale neutron scattering study of any fluorite-type solid electrolyte, and it represents only the second case of oxide ion dynamics in any material observed on a nanosecond time scale by quasielastic neutron scattering. Ab initio molecular dynamics simulations reveal two mechanisms that contribute to the oxide ion dynamics in the material: a slower diffusion process through the Bi–O sublattice and a faster process which corresponds to more localized dynamics of the oxide ions within the VO x coordination spheres. The length of the trajectories simulated and the validation of the simulations by neutron scattering experiments provide for the first time a quantitative insight into the relative contributions of the two processes to the oxide ion conduction in this exceptional solid electrolyte, which can be used to derive design principles for the preparation of related oxide ion conductors with even better properties.

Structure–property correlation in oxide-ion and proton conductors for clean energy applications: recent experimental and computational advancements

“…97 A similar approach was also used to directly observe oxide ion dynamics in bismuth vanadate with formula Bi 0.913 V 0.087 O 1.587 by the same authors of the previous work. 98 The main results in this case was the observation of the presence of two processes contributing to the oxide ion dynamics in Bi 0.913 V 0.087 O 1.587 : the long-range diffusive movement of oxide ions through the Bi-O sublattice, and a localized motion of oxygen atoms within the VO x groups of the bismuth vanadate. 98 This last process does not directly contribute to the long-range conduction but facilitates the movement of oxygen atoms into and out of the VO x groups and, owing to the exible coordination requirements of the V 5+ cation, allows the VO 4 groups to accept additional oxygens atoms from the Bi-O sublattice.…”

“…98 The main results in this case was the observation of the presence of two processes contributing to the oxide ion dynamics in Bi 0.913 V 0.087 O 1.587 : the long-range diffusive movement of oxide ions through the Bi-O sublattice, and a localized motion of oxygen atoms within the VO x groups of the bismuth vanadate. 98 This last process does not directly contribute to the long-range conduction but facilitates the movement of oxygen atoms into and out of the VO x groups and, owing to the exible coordination requirements of the V 5+ cation, allows the VO 4 groups to accept additional oxygens atoms from the Bi-O sublattice. The ability of achieving this atomic-level comprehension of the ion dynamics in oxide ion conductors pave the way to propose design principles for chemical modications of oxide ion conductors to further improve their properties.…”

Oxide Ion Conductivity, Proton Conductivity, and Phase Transitions in Perovskite-Derived Ba3–xSrxYGa2O7.5 0 ≤ x ≤ 3 Materials

“… 1 − 3 There is significant interest in identifying new materials with high conductivity at low temperatures. Structural families of interest for oxide ion conductivity include fluorite derivatives, 4 − 6 apatites, 7 − 9 melilites, 10 − 13 La 2 Mo 2 O 9 , 14 , 15 and others. Perovskite derivatives such as ABO 3−δ and brownmillerites A 2 B 2 O 5 are of interest for both oxide ion and proton conductivity.…”

Understanding the Correlation between Oxide Ion Mobility and Site Distributions in Ba3NbWO8.5

“…Although non-trivial due to the complexity and size of the simulation model and the trajectories needed, such computational studies are possible and, especially when interpreted in conjunction with experimental methods, they can provide qualitative and quantitative insight into oxide ion dynamics in structurally complex materials. [30][31][32][33][34][35][36][37]…”