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Séminaire de Teruyuki Nakato et Nobuyoshi Miyamoto

Liquid Crystals of Niobate Nanosheets

Liquid Crystals of Niobate Nanosheets : Structural Control with Electric Alignment and Phase Separation

Teruyuki Nakato (Kyushu Institute of Technology)

Liquid crystalline colloids of inorganic nanosheets were prepared by
exfoliation of a layered niobate, and their structural control was
examined. The highly anisotropic shape of the nanosheets allowed
alignment with electric force to yield macroscopic arrangement of the
nanosheets. Application of AC voltages induced macroscopic alignment of
the nanosheets with the direction of the nanosheet surface parallel to
the electric field. Addition of morphologically different nanosheets
prepared from clay to the niobate nanosheet colloid to yield apparently
homogeneous liquid crystalline colloid but microphase separation of the
two particles was observed, by which a hierarchal structure was
introduced into the nanosheet liquid crystals.

Nanosheet liquid crystals : the effect of the nanosheet thickness ?

Nobuyoshi Miyamoto (Fukuoka Institute of Technology)

A series of liquid crystalline colloids of the inorganic nanosheets with
varied layer thickness of 1.2- 2.4 nm were prepared by exfoliation of
Dion-Jacobson-type layered perovskites, KCa2Na3-nNbnO3n+1 (n = 3, 4, 5,
and 6), and their isotropic/liquid crystal phase transition behavior and
structure were investigated. The birefringent textures observed by
polarized microscopy confirmed the formation LC phase in the colloid.
Swollen lamellar structures were identified by small-angle X-ray
scattering, while the basal spacing increased to up to 144 nm with
increase in n. The colloids with large basal spacing showed weak
greenish or bluish structural colors.