LAUSR

Manganese oxides with tunnel structures have attracted wide attentions because of their potential applications in rechargeable batteries, ionic exchange, molecular absorption and catalysis. For utilizations as electrode in batteries, knowledge on how the tunneled structures in one-dimensional (1D) nanorods facilitate ionic transport will lead to a better understanding of the structure-property relationship. Manganese oxides can form various kinds of tunnel structures [1]. Figs. 1a-d show four types of the tunnel structures in MnO2, namely 1×1, 2×2, 2×1 and 2×3 structures with various tunnel sizes. In most cases, these tunnels are partially occupied by different cations (e.g. K+, Ag+, Ba2+) and water molecules. To simplify the analyses, here, the atomic occupations within tunnels are not included in these schematics. For 1×1 and 2×1 tunnel structures (Figs. 1a and 1c), it is found that the tunnels are pure 1×1 and 2×1 ones, while for 2×2 and 2×3 tunnel structures (Figs. 1b and 1d), besides 2×2 and 2×3 tunnels, the 1×1 tunnels are intercalated. The K+ stabilized α-MnO2 possess the 2×2 structure. Recently, it was found that many planar defects exist in K+ stabilized α-MnO2 [2]. However, the detailed atomic configurations associated with these planar defects are unknown. In this presentation, we report detailed characterizations on these planar defects.