Rb 2 Ti 2 O 5 : A layered ionic conductor at the sub-micrometer scale

Abstract

Over the past few years, ionic conductors have gained a lot of attention because of the possibility of implementing them in various applications such as supercapacitors, batteries or fuel cells, and resistive memories. Especially, layered two-dimensional (2D) crystals, such as h-BN, graphene oxide, and MoSe2, have been shown to provide unique properties originating from the specific 2D confinement of moving ions. Two important parameters are the ion conductivity and the chemical stability over a wide range of operating conditions. In this vein, Rb2Ti2O5 (RTO) has recently been found displaying remarkable properties such as superionic conduction and equivalent colossal dielectric constant. Here, an approach to the study of the electrical properties of the layered RTO 100-nm scale is presented. Characterizations by means of micro-Raman spectroscopy and atomic force microscopy measurements of mechanically exfoliated RTO micro-flakes via the so-called adhesive-tape technique are reported. Finally, the results of electrical measurements performed on an exfoliated RTO micro-flake are presented and are found to be consistent with the results obtained on macroscopic bulk crystals.