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Nanoparticles of mesoporous MIL-100(Al, Cr or Fe) metal-organic frameworks were synthesized by a microwave-assisted solvothermal route with green solvents. The optimization of yield, crystallinity, and particle size was achieved through the control of synthetic parameters such as temperature, heating rate, and dwelling time. The particle size strongly depends on the metallic cation and the metal and linker precursors; nanoparticles smaller than 100 nm were obtained for iron and chromium based MIL-100. Finally, stable colloidal solutions of iron and chromium MIL-100 nanoparticles were used for thin layer dip-coating deposition, which resulted in high optical quality thin films, the porosity of which was investigated by environmental ellipsometric porosimetry. [ABSTRACT FROM AUTHOR]

Academic and industrial research groups are currently working to obtain high-quality transparent ultralow-refractive-index and ultralow-dielectric-constant thin films, as they are important for designing smart devices and systems for microoptics and microelectronics (for example, multilayer structures, optical resonators, photonic crystals, Cu interconnects, insulating layers and so on). Here, we report a robust and simple procedure to prepare highly porous and resistant semicrystalline magnesium oxyfluoride thin films through liquid deposition followed by a flash and short thermal treatment. These films are water insensitive, mechanically resistant (E=1 GPa), exhibit high optical quality and have an ultralow refractive index (n700 nm=1.09) and an ultralow dielectric constant (k100 kHz=1.6) which are required for the above-mentioned applications. Moreover, the process used to prepare these nanomaterials is well suited for industrial production on larger surfaces. [ABSTRACT FROM AUTHOR]

Abstract: Thickness, refractive index n and extinction coefficient k of eriochrome cyanine R (ECR) dye doped mesostructured silica film (ECRMSSF) dip-coated on silicon wafers without prior removal of surfactant have been determined in the visible range of the spectrum by spectroscopic-ellipsometry (SE). ECRMSSF was used as sensing detection layer of Cu2+ in aqueous solutions of known pH. The dependence of optical parameters on the pH range of the aqueous phase (pH=6–8) was investigated. The detection reversibility of ECRMSSF was demonstrated. An electron paramagnetic resonance spectrum demonstrated the complexation of Cu2+ by the entrapped ECR. [Copyright &y& Elsevier]

Innovative strategies to produce well-defined nanoparticles and other nanostructures such as nanofibres, quantum wells and mesoporous materials have revitalized materials science for the potential benefit to society. Here, we report a controlled process, involving soft-chemistry-based deposition, template-assisted mesostructured growth, and tuned annealing conditions that allows the preparation of ordered mesoporous crystalline networks and mesostructured nano-island single layers, composed of multicationic metal oxides having perovskite, tetragonal or ilmenite structures. This strategy to obtain meso-organized multi-metal-oxide nanocrystalline films (M3NF) bridges the gap between conventional mesoporous materials and the remarkable properties of crystalline ternary or quaternary metallic oxides. Nanocrystalline mesoporous films with controlled wall thickness (10–20 nm) of dielectric SrTiO3, photoactive MgTa2O6 or ferromagnetic semi-conducting CoxTi1−xO2−x were prepared by evaporation-induced self-assembly (EISA) using a specially designed non-ionic block-copolymer template. A tuned thermal treatment of the mesoporous films permits the transfer of the wall structure into nanocrystallites, with all tectonic units being tightly incorporated into mechanically stable ordered tri- or bidimensional nanocrystalline networks. This methodology should allow multifunctionalization, miniaturization and integration during development of devices such as smart sensors and actuators, better-performing photocatalysts, and fast electrochromic devices. On the other hand, organized arrays of dispersed ferromagnetic or ferroelectric nanoparticles are promising materials for spintronics and for cheap, non-volatile 'flash' memories. [ABSTRACT FROM AUTHOR]

Abstract: The thermal stability of anatase TiO2 mesoporous thin films has been considerably increased up to 800°C by substituting a fraction of Ti cations by Nb. Mesoporous mixed oxide films Ti1−x Nb x O2, with x =Nb/(Nb+Ti) ranging from 0 to 1, and homogeneous crystalline walls have been successfully prepared from chloride precursors and non-ionic block copolymer templates. They all exhibit a uniaxially distorted Im3m bcc mesostructure with the a lattice parameter ranging from 14 to 19nm. Films have been characterised by simultaneous in situ SAXS and WAXS investigations during thermal treatment. Transmission electron microscopy and UV–visible ellipsometry were used to confirm the structure, the porosity and the good optical quality. A high porosity of 40% (pore size estimated at 7nm) was maintained for the 10% Nb-doped films above the temperature of crystallisation and a bandgap of 3.40eV has been measured after annealing at 500°C. [Copyright &y& Elsevier]