We demonstrate the fabrication of polymeric membranes that incorporate a few layers of periodically aligned magnetic microchains formed upon the application of variable magnetic fields. A homogeneous solution containing an elastomeric polymer and a small amount of colloidal magnetic nanoparticles is spin coated on glass slides, thereby forming thin magnetic membranes of ca. 10 μm thickness. Subsequent application of a homogeneous magnetic field results in the orientation of the magnetic clusters and their further motion into the matrix along the field lines forming layers of aligned chains. The study of the kinetics of alignment demonstrates that the chains are formed in the first hour of exposure to the magnetic field. Above all, a detailed microscopy study reveals that the dimensions and the periodicity of the microchains are effectively controlled by the intensity of the magnetic field, in good agreement with the theoretical simulations. This ability to form and manipulate the size and the distribution of chains into the polymeric matrix gives the opportunity to develop multifunctional composite materials ready to be used in various applications such as electromagnetic shielding, or multifunctional magnetic membranes etc.

We demonstrate the formation of stable magnetic microwires (MWs) in solution starting from a highly diluted solution of monomer−thermal initiator− superparamagnetic nanoparticles (SMNPs). Under an external magnetic field (MF) the SMNPs get closely packed into wire-like assemblies that become permanently linked due to simultaneous thermal polymerization of the monomer. As the SMNPs assemble in the form of wires under MF, the concentration of the monomer chains adsorbed onto them increases in the near proximity of these assemblies, promoting the polymerization process during heating. This combined process causes the permanent bonding among the SMNPs, forming smooth MWs with metallic character. Detailed microscopic and spectroscopic studies reveal the mechanism of the process and designate the importance of the external MF, the thermal polymerization, and the high dilution factor of the reaction solution for the formation of free-standing uniform wires with controlled size. This method leads to a novel approach to form long magnetic wires with smooth contour and regular shape, which can be used in various fields of applications like in biomedicine, chemistry, fluidics, etc.

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In this research work we present a study on time-sequenced plasma enhanced atomic layer deposition (PE-ALD) processes towards the achievement of high quality α-MoO3 thin films which are suitable for...

We show that assembled domains of magnetic iron-oxide nanoparticles (IONPs) are effective at increasing the dielectric permittivity of polydimethylsiloxane (PDMS) nanocomposites in the GHz frequency range. The assembly has been achieved by means of magnetophoretic transport and its efficacy, as well as the electromagnetic properties of the nanocomposite, has been found to depend on IONPs diameter. Remarkably, the dielectric permittivity increase has been obtained by keeping dielectric and magnetic losses very low, making us envision the suitability of nanocomposites based on aligned IONPs as substrates for radiofrequency applications.

Aluminum bowtie nanoantennas represent a possibility to confine and enhance electromagnetic (EM) field at optical frequencies in subwavelength regions by using an abundant and inexpensive metal. The native oxidation process of this metal is often viewed as a limitation for its application in plasmonics. Here, we show that in close gap configurations, the high refractive index of the native aluminum oxide helps in squeezing the plasmonic mode in extremely reduced size volumes, providing a higher EM near-field confinement and enhancement in the bowtie antenna gaps than achieved in the pure aluminum counterpart. Hence, the study provides new perspectives in the use of such a plasmonic antenna geometry within this aluminum system, which can be useful for improving plasmonics-enabled effects such as surface-enhanced Raman scattering- and light–matter interaction in strong coupling regime.

In this contribution, we present an experimental and numerical study on the coating of Al plasmonic nanostructures through a conformal layer of high-refractive-index molybdenum oxide. The investigated structures are closely coupled nanodisks where we observe that the effect of the thin coating is to help gap narrowing down to the sub-5-nm range, where a large electromagnetic field enhancement and confinement can be achieved. The solution represents an alternative to more complex and challenging lithographic approaches, and results are also advantageous for enhancing the long-term stability of aluminum nanostructures.

Hydrogen has the potential to become a crucial energy storage vector, allowing to maximise the advantages of renewable and sustainable energy sources. Hydrogen is usually stored as compressed hydrogen gas, or liquid hydrogen. However, the former requires high pressure, the latter cryogenic temperatures, being a huge limit to the widespread adoption of these storage methods. Thus, new materials for solid-state hydrogen storage shall be developed. Here we show that a α−MoO3 thin film, grown via atomic layer deposition, is a promising material for reversibly storing hydrogen. We found that hydrogen plasma is a convenient way to hydrogenise − at room temperature and relatively low pressures (500 or 1000 mTorr) − layered monocrystalline α−MoO3 thin films. Hydrogen has been shown to locate itself in the van der Waals gap along the [010] oriented α−MoO3 film. The process has been found to be totally reversible in air. Our essay could be a starting point to a transition from conventional (gas and liquid) to more advantageous solid-state hydrogen storage materials.