A study of Ti${}_n$O${}_{2n-1}$ Magn\'eli phases using Density Functional Theory

TL;DR

This paper uses density functional theory to analyze the electronic structure of Ti${}_n$O${}_{2n-1}$ Magnéli phases, revealing how intrinsic defects contribute to conductivity in memristor applications.

Contribution

It provides the first detailed DFT study of intrinsic defects in Ti${}_n$O${}_{2n-1}$ Magnéli phases, linking defect states to enhanced memristive conductivity.

Findings

Intrinsic defects create states inside the bandgap.

Defect states can act as intrinsic dopants.

Enhanced conductivity in TiO${}_2$ memristors.

Abstract

Defects in the rutile TiO${}_2$ structures have been extensively studied, but the intrinsic defects of the oxygen deficient Ti${}_n$O${}_{2n-1}$ phases have not been given the same amount of consideration. Those structures, known as Magn\'eli phases, are characterized by the presence of ordered planes of oxygen vacancies, also known as shear-planes, and it has been shown that they form conducting channels inside TiO-based memristor devices. Memristors are excellent candidates for a new generation of memory devices in the electronics industry. In this paper we present DFT-based electronic structure calculations for Ti${}_n$O${}_{2n-1}$ Magn\'eli structures using PBESol+U ($0 \leq U \leq 5$ eV) and HSE functionals, showing that intrinsic defects present in these structures are responsible for the appearance of states inside the bandgap, which can act as intrinsic dopants for the enhanced conductivity of TiO${}_2$ memristive devices.