Structural, thermal, dielectric and optical behaviour investigations of water-free ZnO/lyotropic liquid crystal nanocolloids

ABSTRACT

Zinc oxide (ZnO) nanoparticles of spherical symmetry (average size of ≈ 20 nm) have been synthesised via a non-aqueous lyotropic liquid crystalline (LLC) templating process. Lyotropic liquid crystalline nanocolloids are prepared via dispersing 0.05, 0.1 and 0.5 wt.% ZnO nanoparticles in non-aqueous lyotropic phase. No structural phase change has been seen with the doping of nanoparticles as stable lamellar phases are observed in all the cases. Stability of the lamellar structure and orientation of the ZnO nanoparticles in the liquid crystalline matrix may be attributed to the interfacial surface charge interactions. A significant increase and pronounced dispersion in dielectric permittivity of the ZnO/LLC nanocolloids could be the result of parallel coupling among guest/host, higher dipole- moment of the ZnO nanoparticles and Maxwell-Wagner polarisation. The variation of relaxation parameters has also been discussed and correlated with the dielectric and structural parameters. ZnO/lyotropic nanocolloids devices exhibit dc conductivity of the order of 10⁻⁵S/m owing to the increase in the number of ions (of the order of 10¹⁹m⁻³) in the doped systems. Nanocolloids exhibits, the refractive index of range 1.40 to 1.45 and the wide bandgap of the range 4.1–4.5 eV.

Graphical abstract

KEYWORDS:

• Non-aqueous lyotropic liquid crystal templates
• zinc oxide nanoparticles
• lyotropic nanocolloids
• dielectricand relaxation spectroscopy
• Dc conductivity
• bandgap

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work has been financially supported by Science and Engineering Research Board (SERB), India (Project Number: EMR/2016/005591) and DIT university under the seed money scheme (project number: DITU/R&D/2017/1/Phy.)