Dielectric properties of magnetic nanoparticles’ suspension in a ferroelectric liquid crystal

Abstract

Colloids of elongated γ-Fe 2 O 3 magnetic nanoparticles (NPs) in a ferroelectric liquid crystal (FLC) were studied. Decreasing the dielectric strength of the Goldstone mode and changing the value of Cole-Cole parameter were found in the suspensions. It was also shown that the effect of introducing magnetic particles into a FLC consists of increasing the electric field strength magnitude required for unwinding its helical structure. Effect of magnetic field on dielectric properties of the FLC colloid was also studied. Dielectric constant measured under static magnetic field is different for the FLC host and FLC doped with the NPs.

Threshold properties of nanodoped surface stabilized ferroelectric liquid crystals under electric and magnetic fields

“…We have also calculated the maximum deviations of the c-director. Our results, confirm the strong influence of the ferroelectric nanoparticles on magnetic threshold field as well as electric threshold field, even at low considerations, which is in agreement with some new experimental reports [21,30]. It also turns out that the shift of transition fields depends on the volume fraction and the geometrical parameters of the nanoparticles as well as their permanent polarization and other material parameters.…”

“…The obtained results show that both electric and magnetic threshold fields of Fredericks transition depend on the polarization of the nanoparticles as well as spontaneous polarization and dielectric anisotropy of the liquid crystal host. The dependence of the obtained magnetic threshold field on the electric dipole moments of dispersed nanoparticles as well as the spontaneous polarization of ferroelectric liquid crystal is an important result which is in agreement with some new experimental reports [21,30]. Obviously, the shift of transition fields is connected with the volume fraction and the geometrical parameters of the nanoparticles in addition to their permanent polarization.…”

“…The maximum deviations of the director could be easily determined by using the boundary condition at the walls of the slab φðAE d 2 Þ ¼ 0, and pursuing the same process in our previous work [21]. Finally, we obtain…”

“…They developed a phenomenological model on SSFLC nanocomposite, in order to explain their experimental findings. Popova et al [21] investigated the dielectric properties of magnetic nanoparticles suspension in a FLC system. They experimentally found the dependence of dielectric permittivity of the FLC host on the magnetic field applied along the smectic layers.…”

Electro-optic, dielectric and optical studies of NiFe2O4-ferroelectric liquid crystal: a soft magnetoelectric material

“…Various MNPs, namely γ-Fe 2 O 3 , Fe 3 O 4, Ni, Co-ferrite of different sizes, shapes and coated with oleic acid surfactant, were dispersed in nematic and FLCs mixtures and showed better transmittance, memory effect and electro-optical responses. [23][24][25][26][27][28] In the present work, efforts have been made to study the effect of nickel ferrite nanoparticles (NFNPs) concentration on the electro-optic, dielectric and optical properties of FLC.…”