Metallic nano-structures for polarization-independent multi-spectral filters

A Review on Preparation and Applications of Silver-Containing Nanofibers

Silver-containing nanofibers are of great interest recently because of the dual benefits from silver particles and nanofibers. Silver nanoparticles are extensively used for biomedical applications due to the antibacterial and antiviral properties. In addition, silver nanoparticles can excite resonance effect of light trapping when pairing with dielectric materials, such as polymer. Comparing to the traditional fabrics, polymer nanofibers can provide larger number of reaction sites and higher permeability contributed to their high surface-to-volume ratio and high porosity. By embedding the silver nanoparticles into polymer nanofiber matrix, the composite is promising candidates for biomaterials, photovoltaic materials, and catalysts. This work demonstrates and evaluates the methods employed to synthesize silver nanoparticle-containing nanofibers and their potential applications.

Angular and polarization properties of cross-holes nanostructured metallic filters

It has been shown in literature that cross-shaped holes arrays can be made insensitive to polarization at normal incidence, and can even feature good stability for off-normal incidence. In this work we look for the optimal design rules to obtain high spectral stability conditions in the visible for those structures, through a complete review of all geometrical parameters using CMOS-compatible materials. Rigorous Coupled Wave Analysis (RCWA) simulations have been used to identify the most-impacting parameters and to determine typical ranges allowing for the realization of low-color errors image sensors whatever the light incidence. It appears that the two main parameters are the ratio of the arm width to the arm length of the crosses and the distance between crosses, which both have to be low to ensure stable responses of the filters. We demonstrate the results with CIE chromaticity diagrams reporting the responses of a RGB filter designed with the established rules under various illumination conditions.

Surface reactivity of hydroxyapatite nanocoatings deposited on iron oxide magnetic spheres toward toxic metals

HYPOTHESIS

Hydroxyapatite and magnetite are two environmentally-friendly mineral phases that have fruitful properties for remediation process. The formation of magnetic core@sorbent shell nanostructures should provide efficient materials for toxic metal removal from aqueous media. However the nanoscale confinement of hydroxyapatite may influence its reactivity.

EXPERIMENTS

Fe3O4@Hydroxyapatite nanocomposites were prepared by surface-controlled precipitation of hydroxyapatite layers from 10 nm to 150 nm in thickness on iron oxide spheres. The surface reactivity of the core-shell particles toward selected inorganic ions of environmental relevance (Pb(II), Y(III), Eu(III), Sb(III)) was studied by batch sorption experiments, X-ray diffraction and electron microscopy.

FINDINGS

The reactivity of the hydroxyapatite coating varied from partial cation exchange to dissolution/transformation of the shell. The nature and extent of the reactions depended significantly on the hydroxyapatite layer structure but was not significantly influenced by the magnetic core. These novel nanocomposites should be useful for environmental applications.

Double-perovskite magnetic La2NiMnO6 nanoparticles for adsorption of bovine serum albumin applications

Double-perovskite La2NiMnO6 (LNMO) nanoparticles were synthesized by co-precipitation process, and the adsorption of bovine serum albumin (BSA) protein on these nanoparticles was carried out. The powder samples were annealed at 750, 850, 950, and 1,050°C, respectively. X-ray diffraction (XRD) results reveal that there are double perovskites and exhibit mixed orientations, without any impurity phases. Transmission electron microscopy results as well as the XRD estimate results show that the crystalline size is about 34 to 40 nm. The adsorption of BSA on the magnetic nanoparticles was analyzed using a UV spectrophotometer at room temperature. The results show that the as-prepared LNMO nanoparticles display a good adsorbing ability for BSA, and the nanoparticle sintered at 850°C has the highest value of 219.6 mg/g, which is much higher than others.

Metallic nano-particles for trapping light

We study metallic nano-particles for light trapping by investigating the optical absorption efficiency of the hydrogenated amorphous silicon thin film with and without metallic nano-particles on its top. The size and shape of these nano-particles are investigated as to their roles of light trapping: scattering light to the absorption medium and converting light to surface plasmons. The optical absorption enhancement in the red light region (e.g., 650nm) due to the light trapping of the metallic nano-particles is observed when a layer of metallic nano-particle array has certain structures. The investigation of the light with incident angles shows the importance of the coupling efficiency of light to surface plasmons in the metallic nano-particle light trapping. PACS: 73.20.Mf, 42.25.s, 88.40.hj.