Water–titanate intercalated nanotubes: fabrication, polarization, and giant dielectric property

Abstract

What's the difference when water molecules are confined in a rather limited space? This work addresses this question by decorating water molecules within the scrolled titanate nanotubes. Both scrolled nanotubes Na_0.96H_1.04Ti₃O₇·nH₂O and Na_0.036H_1.964Ti₃O₇·nH₂O were first prepared to show large specific areas around 200 m² g⁻¹, within which quantities of water molecules were confined to form H₂O tubes that are alternatively arranged with the titanate nanotubes. This unique double-tube structure exhibited remarkable polarization and dielectric performance, yielding a huge dielectric constant around ε = 14 000, comparable to some known giant-dielectric-constant ceramics. Depending on the measurement frequency and temperature, the dielectric relaxation peaks were monitored by the content of the water molecules confined within the nanotubes. A two-layer dielectric model that involves the distinct anisotropy and confinement effect of the double-tube structure was proposed to explain this dielectric behavior. The findings reported in this work may pave the way for optimizing many subtle hydrated nanostructures in nature that could create an abundance of confined water molecules for a broad class of applications.