How the aggregation of oxygen vacancies in rutile based TiO$_{2-\delta}$ phases causes memristive behavior

TL;DR

This paper investigates how the arrangement of oxygen vacancies in rutile TiO$_{2- ext{delta}}$ influences its memristive behavior, revealing that vacancy-induced metallic phases are structurally similar to Magnéli phases but energetically less stable.

Contribution

It provides a systematic ab-initio analysis showing the formation of planar oxygen vacancy arrangements leading to metallic, memristive properties in reduced TiO$_2$ phases.

Findings

Oxygen vacancies tend to form planar arrangements.

These arrangements induce metallic behavior.

Meta-stable structures resemble Magnéli phases but are less stable.

Abstract

The results of a comprehensive and systematic ab-initio based ground-state search for the structural arrangement of oxygen vacancies in rutile phase TiO$_2$ provide new insights into their memristive properties. We find that O vacancies tend to form planar arrangements which relax into structures exhibiting metallic behavior. These meta-stable arrangements are structurally akin to, yet distinguishable from the Magn\'eli phase. They exhibit a more pronounced metallic nature, but are energetically less favorable. Our results confirm a clear structure-property relationship between segregated oxygen vacancy arrangement and metallic behavior in reduced oxides.