Orientation of colloidally suspended LiNbO3 nanocrystals in externally applied electric fields

Abstract

Electric fields are applied to lithium niobate nanoparticles of 41 nm radius colloidally suspended in heptane. Interferometric measurements of field-induced refractive index changes show that the particle orientation is dominated by induced dipole moments. There are indications that a permanent dipole moment of the nanoparticles of 10−26 C m along their crystallographic c-axis is present as well. An electric field of 2 kV/mm is sufficient to align 80% of the particles, such that the angle between their c-axis and the applied electric field direction is less than 70°, making applications of such a liquid with electrically controlled optical properties feasible.