Facile synthesis of iodine variants-incorporated lithium perrhenate crystal and film: Resistive switching device and synaptic behavior

Abstract

This study investigates the integration of iodine as a dopant into lithium perrhenate (LiReO4) using rhenium oxide (Re2O7) as a precursor, aiming to enhance the electrical conductivity of the compound, with implications for various material science applications. The iodine variants-incorporated LiReO4 (Iv@LiReO4·H2O) exhibits a notable improvement in the average electrical conductivity (∼ 2 S/cm) and light absorption across a broad spectrum, extending to the near-infrared range. Additionally, the doping process induces resistive switching and synaptic behaviors due to iodine diffusion. The presence of iodine and the partial reduction of Re oxide is confirmed by X-ray photoelectron spectroscopy, while UV-Vis absorption spectroscopy indicates the existence of incorporated iodine variants species. Density functional theory calculations further elucidate the mechanism by which iodine doping triggers a significant enhancement in electrical conductance, primarily by introducing a mixed-valence oxidation state in rhenium, leading to the narrowing of the band gap from 3.68 eV to 0.33 eV. This research suggests potential uses for Iv@LiReO4·H2O in applications to memristive neuromorphic devices. © 2024 Elsevier B.V.