Ionic memristive effects on the nanometre scale in metal oxides: Understanding the process of valence change

Abstract

Relevance. The relevance of the study is due to the great potential of memristive effects, which are manifested in the change of material resistance under the influence of an external electric field and ionic fluxes. Aim. The aim is to analyse and study the mechanisms of ionic memristive effects, with a detailed consideration of the process of changing the valence of metal cations. Methodology. The work was based on the study of nanometre-sized metal oxides TiO2 and ZrO2. The materials were obtained by synthesis by chemical deposition using high-purity precursors. Results. The obtained results open up wide opportunities for the practical use of ionic membrane effects. The study of ionic memristive effects in TiO2 and ZrO2-based films has shown that the change in resistance occurs due to various mechanisms, including ionic migration, electrochemical reactions, and defect reorganization. Under the influence of an external electric field, a change in the resistance of both materials is observed. In TiO2, the resistance decreases with increasing voltage, while in ZrO2, an increase in resistance is observed. During additional experiments in the temperature range of 25-200 ℃, it was found that temperature significantly affects the ionic membrane effects. With its increase, a noticeable increase in the intensity of these effects in both materials is observed. Conclusions. The use of X-ray diffractometry and infrared spectroscopy revealed that changes in the valence of metal cations in both films occur under the influence of an electric field. The analysis of changes in the X-ray and infrared spectra showed the presence of modifications in the crystal and molecular structure in response to the electric field. In particular, the change in the positions and intensity of the peaks indicates a restructuring of the bonds in the crystal lattice. The paper proposes new studies to expand the understanding of these effects and to consider possible ways to improve membrane devices. The study of ionic memristive effects in TiO2 and ZrO2 is of great practical importance for the development of electronics and the creation of new generations of memristors and neuromorphic systems.