Electric-Field-Induced Reversible Phase Transitions in a Spontaneously Ion-Intercalated 2D Metal Oxide.

Rasouli, Hamid Reza; Kim, Jeongho; Mehmood, Naveed; Sheraz, Ali; Jo, Min-Kyung; Song, Seungwoo; Kang, Kibum; Kasirga, Talip Serkan · Nano Lett · 2021

basic_science · Level V

Where this comes from

Abstract

Electric field driven reversible phase transitions in two-dimensional (2D) materials are appealing for their potential in switching applications. Here, we introduce potassium intercalated MnO<sub>2</sub> as an exemplary case. We demonstrate the synthesis of large-area single-crystal layered MnO<sub>2</sub> via chemical vapor deposition as thin as 5 nm. These crystals are spontaneously intercalated by potassium ions during the synthesis. We showed that the charge transport in 2D K-MnO<sub>2</sub> is dominated by motion of hydrated potassium ions in the interlayer space. Under a few volts bias, separation of potassium and the structural water leads to formation of different phases at the opposite terminals, and at larger biases K-MnO<sub>2</sub> crystals exhibit reversible layered-to-spinel phase transition. These phase transitions are accompanied by electrical and optical changes in the material. We used the electric field driven ionic motion in K-MnO<sub>2</sub> based devices to demonstrate the memristive capabilities of two terminal devices.