Pulse duration dependent optical nonlinearities of BiSe thin films.

Topological insulators, such as the BiSe material, exhibit significant optical nonlinearities. This work investigates the impact of the pulse duration on the nonlinear optical responses of BiSe layers. Scanning electron microscopy studies have been performed to reveal the crystalline structure of the samples.

Evolution of Corrosion Products Formed during the Corrosion of MgZr Alloy in Poral Solutions Extracted from Na-Geopolymers Used as Conditioning Matrix for Nuclear Waste.

Geopolymer, a nanoporous aluminosilicate filled with water and ions, has been selected as a potential matrix to encapsulate MgZr alloy fuel cladding. In this study, we investigate the evolution of the corrosion products formed during the corrosion of MgZr in poral solutions extracted from geopolymers with and without NaF as corrosion inhibitor. Using various characterization techniques such as Scanning Electron and Scanning Transmission Electron Microscopies coupled to Energy Dispersive X-ray spectroscopy and Grazing Incidence X-ray Diffraction, we show that the amounts of dissolved silica and fluoride species in solution are the key parameters driving the nature of corrosion products and probably their passivating properties regarding MgZr corrosion.

Symbiotic cooperation between freshwater rock-boring bivalves and microorganisms promotes silicate bioerosion.

Bioerosion is a process with a high socio-economic impact that contributes to coastal retreat, and likely to increase with climate change. Whereas limestone bioerosion is well explained by a combination of mechanical and chemical pathways, the bioerosion mechanisms of silicates, which are harder and chemically more resistant, remain elusive. Here we investigated the interface between siltstone and freshwater rock-boring bivalves Lignopholas fluminalis (Bivalvia: Pholadidae).

Fabrication of core-shell nanostructures via silicon on insulator dewetting and germanium condensation: towards a strain tuning method for SiGe-based heterostructures in a three-dimensional geometry.

We report on a novel method for the implementation of core-shell SiGe-based nanocrystals combining silicon on insulator dewetting in a molecular beam epitaxy reactor with an ex situ Ge condensation process. With an in situ two-step process (annealing and Ge deposition) we produce two families of islands on the same sample: Si-rich, formed during the first step and, all around them, Ge-rich formed after Ge deposition. By increasing the amount of Ge deposited on the annealed samples from 0 to 18 monolayers, the islands' shape in the Si-rich zones can be tuned from elongated and flat to more symmetric and with a larger vertical aspect ratio.

Nanometre-scale evidence for interfacial dissolution-reprecipitation control of silicate glass corrosion.

Silicate glasses are durable solids, and yet they are chemically unstable in contact with aqueous fluids-this has important implications for numerous industrial applications related to the corrosion resistance of glasses, or the biogeochemical weathering of volcanic glasses in seawater. The aqueous dissolution of synthetic and natural glasses results in the formation of a hydrated, cation-depleted near-surface alteration zone and, depending on alteration conditions, secondary crystalline phases on the surface. The long-standing accepted model of glass corrosion is based on diffusion-coupled hydration and selective cation release, producing a surface-altered zone.

TiO₂-based nanoparticles released in water from commercialized sunscreens in a life-cycle perspective: structures and quantities.

This work investigates the physical-chemical evolution during artificial aging in water of four commercialized sunscreens containing TiO₂-based nanocomposites. Sunscreens were analyzed in terms of mineralogy and TiO₂ concentration. The residues formed after aging were characterized in size, shape, chemistry and surface properties.

TEM and HRTEM evidence for the role of ligands in the formation of shape-controlled platinum nanoparticles.

The morphology of platinum nanoparticles synthesized using an organometallic approach from PtMe(2) (C(8) H(12) ) is influenced by the nature of the ligands used as stabilizing agents. The use of long alkyl chain amines leads to the formation of multipodal nanoparticles that transform into compact nano-objects, adopting cubic, truncated cubic, or cuboctahedral shapes. In contrast, the use of diamine ligands allows the growth of compact (111) arrowlike faces, forming polycrystalline nanoparticles of an overall desert-rose aspect.

Aging of TiO(2) nanocomposites used in sunscreen. Dispersion and fate of the degradation products in aqueous environment.

Aging in water of a TiO(2)-based nanocomposite used in sunscreen cosmetics has been studied as a function of light and time. It consisted initially in a TiO(2) core, coated with Al(OH)(3) and polydimethylsiloxane (PDMS) layers. Size measurement, coating alteration, and surface charge were followed by laser diffraction, TEM/EDS, ICP-AES and electrophoretic mobility measurement.

In situ deformation of thin films on substrates.

Metallic thin-film plasticity has been widely studied by using the difference between the coefficients of thermal expansion of the film and the underlying substrate to induce stress. This approach is commonly known as the wafer curvature technique, based on the Stoney equation, which has shown that thinner films have higher yield stresses. The linear increase of the film strength as a function of the reciprocal film thickness, down to a couple hundred nanometers, has been rationalized in terms of threading and interfacial dislocations.