3D Hexagonal (R‐3m) Mesostructured Nanocrystalline Titania Thin Films: Synthesis and Characterization

Abstract

A straightforward and reproducible synthesis of crack‐free large‐area thin films of 3D hexagonal (R‐3m) mesostructured nanocrystalline titania (meso‐nc‐TiO2) using a Pluronic triblock copolymer (P123)/1‐butanol templating system is described. The characterization of the films is achieved using a combination of electron microscopy (high‐resolution scanning electron microscopy and scanning transmission electron microscopy), grazing‐incidence small‐angle X‐ray scattering, in situ high‐temperature X‐ray diffraction, and variable‐angle spectroscopic ellipsometry. The mesostructure of the obtained films is found to be based upon a 3D periodic array of large elliptically shaped cages with diameters around 20 nm interconnected by windows of about 5 nm in size. The mesopores of the film calcined at 300 °C are very highly ordered, and the titania framework of the film has a crystallinity of 40 % being composed of 5.8 nm sized anatase crystallites. The film displays high thermal stability in that the collapse of the pore architecture is incomplete even at 600 °C. The accessible surface area of 3D hexagonal meso‐nc‐TiO2 estimated by the absorption of methylene blue is nearly twice as large as that of 2D hexagonal meso‐nc‐TiO2 at the same annealing temperature.

Electrochemical Tuning of Magnetism in Ordered Mesoporous Transition-Metal Ferrite Films for Micromagnetic Actuation

“…The patterns in Figure show strong scattering maxima in the q y direction, indicating that the lateral pore structure is only affected to a minor extent by the heating. The lack of scattering along q z (out-of-plane direction) is due to the morphological anisotropy of the films, which is in agreement with previous findings. ,,,,− From the GISAXS data, we conclude that NiFe 2 O 4 exhibits the highest degree of in-plane pore ordering in the crystalline state. This material also appears to be more stable (thermally) than both CoFe 2 O 4 and Co 0.5 Ni 0.5 Fe 2 O 4 .…”

“…The lack of scattering along qz (out-of-plane direction) is due to the morphological anisotropy of the films, which is in agreement with previous findings. 12,16,17,32,[43][44][45] From the GISAXS data, we conclude that NiFe2O4 exhibits the highest degree of in-plane pore ordering when in the crystalline state. This material also appears to be more stable (thermally) than both CoFe2O4 and Co0.5Ni0.5Fe2O4.…”

Mesoporous Titania Thin Film with Highly Ordered and Fully Accessible Vertical Pores and Crystalline Walls

“…Choi et al. reported the formation of an R $\bar 3$ m ‐structured MTTF 14. However, the pores in their films are isolated, in contrast to ours.…”

Encapsulation of Conjugated Polymers in Block Copolymer-Templated Mesostructured Oxides: A Cosolvent Assisted Approach

“…The pattern includes 10 well resolved diffraction spots (Figure c), reflecting a combination of rhombohedral and hexagonal mesostructures. The rhombohedral structure, with a d 111 -spacing of about 11 nm corresponding to a lattice parameter of ∼15 nm, is a result of an uneven contraction of a cubic mesostructure, as previously reported for conventionally prepared cubic silica and titania templated by P123. , The slight increase in the lattice parameter upon addition of conjugated polymers and xylene to the precursor solution, from 13 to 15 nm, could be indicative of surfactant domain swelling by xylene incorporation into the hydrophobic cores of the P123 micelles. This increase of hydrophobic domain-size in the surfactant assemblies also reduces the assembly curvature inducing the appearance of the hexagonal mesostructure.…”