Preparation of optical active single-handed helical barium titanate nanotubes and characterization of dielectric properties

Left and right-handed helical barium titanate nanotubes are prepared with the impregnation of Ba(OH)2 into single-handed helical titania nanotubes. Wide angle X-ray diffraction pattern and transmission electron microscopy image indicate that they are constructed by nanoparticles with a partially crystalline structure. The diffuse reflectance circular dichroism spectra indicate that they exhibit optical activity which was proposed to originate from chiral defects on the inner surfaces of the nanotubes. Both the dielectric constant and tanδ decrease with increasing the frequency. At 10 and 100 Hz, one dielectric constant peak at 9.6℃ and one tanδ peak at 5.0℃ are observed at -120℃ to 180℃.