Liquid Crystalline Nature of K4Nb6O17 Nanosheet Sols and Their Macroscopic Alignment

Abstract

Liquid crystallinity of layered niobate K4Nb6O17 colloidally dispersed via exfoliation has been achieved as evidenced by birefringence of the colloid (see Figure). Due to the large lateral size of the nanosheets, the liquid‐crystalline state is stable down to low concentrations and macroscopic alignment is easily induced by gravitational force. Potential applications of these nanosheets as anisotropic soft nanohybrids can be foreseen.

Hydrothermal synthesis of NaNbO3 with low NaOH concentration

“…Cho synthesized (Na,K)NbO 3 thin films with chemical vapor deposition [2]. The synthesis of KNbO 3 has been widely investigated, while there are few papers on NaNbO 3 [3][4][5][6][8][9][10][11]16,18,23,24].…”

“…Currently, the hydrothermal synthesis of alkaline niobate powders has attracted much attention for its advantages, such as high degree of chemical homogeneity achieved on molecular scale, use of mild temperatures and pressures, a single step for the synthesis of nanocrystalline powders, and elimination of high-temperature calcination and ball-milling procedures [16,17,21,[23][24][25][26] [8]. In the previous work on hydrothermal syntheses of NaNbO 3 , all the reaction conditions involved high [OH À ], with the result that its liquid waste was very harmful to the environment.…”

Preparation of porous solids composed of layered niobate walls from colloidal mixtures of niobate nanosheets and polystyrene spheres

“…In contrast, the situation is different when the size of nanosheets is comparable or larger than the spheres. The nanosheets are aligned as a lamellar mesophase of liquid crystalline state due to excluded volume effect which is more effective for larger nanosheets [17,18]. The spheres are supposed to be present separated from the nanosheet domains or present between the interlamellar spaces formed by the nanosheets.…”

“…While nanosheets have widely been utilized as components to fabricate solid-state nanomaterials such as ion-exchangeable multilayered films [14,15], and nanotubes [16], colloids composed of nanosheets show fascinating characters such as liquid crystals [17,18] and pH-responsible gelators [19]. These colloidal properties owe mainly to the specific shape of nanosheets: crystallographically determined thickness of one to several nm and lateral size up to 100 µm or larger [16,20].…”

Preparation and some properties of organically modified layered alkali titanates with alkylmethoxysilanes

“…Moreover, the octadecylsilylated derivatives swelled in organic solvents [31,32]. This property is worth mentioning as a characteristic of the materials, since there were several successful examples on the preparation and characterization of aqueous suspensions of layered alkali titanates [33], niobates [34] and titanoniobates [35].…”