Forging Fast Ion Conducting Nanochannels with Swift Heavy Ions: The Correlated Role of Local Electronic and Atomic Structure

Abstract

Atomically disordered oxides have attracted significant attention in recent years due to the possibility of enhanced ionic conductivity. However, the correlation between atomic disorder, corresponding electronic structure, and the resulting oxygen diffusivity is not well understood. The disordered variants of the ordered pyrochlore structure in gadolinium titanate (Gd2Ti2O7) are seen as a particularly interesting prospect due to intrinsic presence of a vacant oxygen site in the unit atomic structure, which could provide a channel for fast oxygen conduction. In the present work, we provide insights into the subangstrom scale on the disordering-induced variations in the local atomic environment and its effect on the electronic structure in high-energy ion irradiation-induced disordered nanochannels, which can be utilized as pathways for fast oxygen ion transport. With the help of an atomic plane-by-plane-resolved analyses, the work shows how the presence of various types of TiO x polyhedral that exist in the amorphous and disordered crystalline phase modify the electronic structures relative to the ordered pyrochlore phase in Gd2Ti2O7. The correlated molecular dynamics simulations on the disordered structures show a remarkable enhancement in oxygen diffusivity as compared with ordered pyrochlore lattice and make that a suitable candidate for applications requiring fast oxygen conduction.

Massively enhanced ionic transport in irradiated crystalline pyrochlore

“…The transition is too sharp to say that there is a gradient in disorder, but it does show that GTO can be disordered, at least in part, in some cases. [38][39][40] The conductivity of lms exposed to varying He uence is plotted in Arrhenius form in Fig. 3 and is observed to increase with increasing uence, i.e.…”

Electrical Transition in Isostructural VO2 Thin-Film Heterostructures

“…Spectra were acquired using a 0.25 eV ch −1 dispersion with a ∼35 pA probe current and 0.07 nm pixel size to perform elemental analysis of V-L 2,3 (513, 521 eV), O-K 1 (529, 532 eV), and Ni-L 2,3 (855, 872 eV). A peak fitting routine was performed on V-L and O-K edges using Gaussian profiles for detailed analysis 46–48 .…”

Computationally accelerated discovery of high entropy pyrochlore oxides

“…For example, significant enhancement in multicomponent systems compared to the end members is demonstrated for oxygen conduction in disordered pyrochlores [11], piezoelectric properties in perovskites [12], and thermal resistance in high entropy ceramics [13,14]. Furthermore, recent investigations of ionic conductivity and mechanical properties of entropy stabilized oxide in the rock salt structure revealed lithium superionic conductivity [15] and unusual elastic anisotropy [16], respectively.…”