Sintering and mechanical properties of β‐SiC powder obtained from waste tires

Plasma synthesized SiC powder obtained from quartz and carbonaceous residue of waste tires was successfully sintered at 1925 ℃ by pressureless liquid-phase method using yttria and alumina as sintering aids (T-SiC). Comparison with sintered SiC obtained from commercial powder (C-SiC) put in evidence of similar sintered density (98%T.D.), but much finer microstructure of T-SiC than that of C-SiC. T-SiC also showed higher flexural strength than C-SiC both at room temperature (508 vs. 458 MPa) and at 1500 ℃ (280 vs. 171 MPa). Difference in liquid phase was responsible for the differences in hardness and fracture toughness. The high value of the Young's modulus of T-SiC (427 MPa) confirmed the high degree of sinterability of this powder and that it can be a promising candidate for structural applications with high added value. © 2016, The Author(s)

New fluorescent polymeric nanocomposites synthesized by antimony dodecyl-mercaptide thermolysis in polymer

In this work, the formation of semiconductive Sb2S3 nanoparticles inside amorphous polystyrene has been achieved by thermal degradation of the corresponding antimony dodecyl-mercaptide, Sb(SC12H25)3. The thermolysis of the dodecyl-mercaptide precursor was studied as both pure phase and mercaptide solution in polystyrene. The thermal decom- position of the antimony mercaptide precursor at 350°C, under vacuum, showed the formation of a mixture of antimony trisulfide (stibnite, Sb2S3) and zero-valent antimony (Sb) phase. X-ray Powder Diffraction (XRD) and Rietveld analysis carried out on the obtained nanostructured powder confirmed the presence of Sb and Sb2S3 phases in 10.4 wt% and 89.6 wt% amount, respectively. The same pyrolysis reaction was carried out in the polymer and the resulting nanocompos- ite material was characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), UV-VIS spec- troscopy, and fluorescence spectroscopy. The nanocomposite structural characterization indicated the presence of well-dispersed nanoclusters of antimony and stibnite (15-30 nm in size) inside the amorphous polymeric phase. Optical measurements on the obtained nanocomposite films showed a strong emission at 432 nm upon excitation at 371 nm, prob- ably related to the presence of Sb2S3 nanoclusters

Photon Management in Two-Dimensional Disordered Media

Elaborating reliable and versatile strategies for efficient light coupling between free space and thin films is of crucial importance for new technologies in energy efficiency. Nanostructured materials have opened unprecedented opportunities for light management, notably in thin-film solar cells. Efficient coherent light trapping has been accomplished through the careful design of plasmonic nanoparticles and gratings, resonant dielectric particles and photonic crystals. Alternative approaches have used randomly-textured surfaces as strong light diffusers to benefit from their broadband and wide-angle properties. Here, we propose a new strategy for photon management in thin films that combines both advantages of an efficient trapping due to coherent optical effects and broadband/wide-angle properties due to disorder. Our approach consists in the excitation of electromagnetic modes formed by multiple light scattering and wave interference in two-dimensional random media. We show, by numerical calculations, that the spectral and angular responses of thin films containing disordered photonic patterns are intimately related to the in-plane light transport process and can be tuned through structural correlations. Our findings, which are applicable to all waves, are particularly suited for improving the absorption efficiency of thin-film solar cells and can provide a novel approach for high-extraction efficiency light-emitting diodes

Bethe-hole polarization analyser for the magnetic vector of light

The nature of light as an electromagnetic wave with transverse components has been confirmed using optical polarizers, which are sensitive to the orientation of the electric field. Recent advances in nanoscale optical technologies demand their magnetic counterpart, which can sense the orientation of the optical magnetic field. Here we report that subwavelength metallic apertures on infinite plane predominantly sense the magnetic field of light, establishing the orientation of the magnetic component of light as a separate entity from its electric counterpart. A subwavelength aperture combined with a tapered optical fibre probe can also serve as a nanoscale polarization analyser for the optical magnetic field, analogous to a nanoparticle sensing the local electric polarization. As proof of its functionality, we demonstrate the measurement of a magnetic field orientation that is parallel to the electric field, as well as a circularly polarized magnetic field in the presence of a linearly polarized electric field

Magnetic hot spots in closely spaced thick gold nanorings

This document is the Accepted Manuscript version of a Published Work that appeared in final form in Nano Letters, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see http://pubs.acs.org/page/policy/articlesonrequest/index.htmlLigh-matter interaction at optical frequencies is mostly mediated by the electric component of the electromagnetic field, with the magnetic component usually being considered negligible. Recently, it has been shown that properly engineered metallic nanostructures can provide a magnetic response at optical frequencies originated from real or virtual flows of electric current in the structure. In this work, we demonstrate a magnetic plasmonic mode which emerges in closely spaced thick gold nanorings. The plasmonic resonance obtains a magnetic dipole character by sufficiently increasing the height of the nanorings. Numerical simulations show that a virtual current loop appears at resonance for sufficiently thick nanorings, resulting in a strong concentration of the magnetic field in the gap region (magnetic hot spot). We find that there is an optimum thickness that provides the maximum magnetic intensity enhancement (over 200-fold enhancement) and give an explanation of this observation. This strong magnetic resonance, observed both experimentally and theoretically, can be used to build new metamaterials and resonant loop nanoantennas at optical frequencies.This work has been supported by Spanish Government and European Union (EU) funds under contracts CSD2008-00066 and TEC2011-28664-C02-02 and Universitat Politecnica de Valencia (program INNOVA 2011). The authors extend special thanks to Mr. J. Ross Aitken for his contribution to this work.Lorente Crespo, M.; Wang, L.; Ortuño Molinero, R.; García Meca, C.; Ekinci, Y.; Martínez Abietar, AJ. (2013). Magnetic hot spots in closely spaced thick gold nanorings. Nano Letters. 13(6):2654-2661. https://doi.org/10.1021/nl400798sS2654266113