Search

We present narrow-band polarization-sensitive reflectance of GaN/AlGaN heterostructures in the mid-infrared range. Experimental measurements performed at 15° angle of incidence show the excitation of a Berreman mode at the interface between GaN and sapphire substrate. A transfer matrix method for anisotropic layers has been used to analyze the obtained results. The contribution of the two-dimensional electron gas at the interfaces of the heterostructures has been included by proper modelization of an effective thin layer.

MoS2 is a two-dimensional layered transition metal dichalcogenide with unique electronic and optical properties. The fabrication of ultrathin MoS2 is vitally important, since interlayer interactions in its ultrathin varieties will become thickness-dependent, providing thickness-governed tunability and diverse applications of those properties. Unlike with a number of studies that have reported detailed information on direct bandgap emission from MoS2 monolayers, reliable experimental evidence for thickness-induced evolution or transformation of the indirect bandgap remains scarce. Here, the sulfurization of MoO3 thin films with nominal thicknesses of 30 nm, 5 nm and 3 nm was performed. All sulfurized samples were examined at room temperature with spectroscopic ellipsometry and photoluminescence spectroscopy to obtain information about their dielectric function and edge emission spectra. This investigation unveiled an indirect-to-indirect crossover between the transitions, associated with two different Λ and K valleys of the MoS2 conduction band, by thinning its thickness down to a few layers. [ABSTRACT FROM AUTHOR]

The growing world energy consumption, with reliance on conventional energy sources and the associated environmental pollution, are considered the most serious threats faced by mankind. Heterogeneous photocatalysis has become one of the most frequently investigated technologies, due to its dual functionality, i.e., environmental remediation and converting solar energy into chemical energy, especially molecular hydrogen. H2 burns cleanly and has the highest gravimetric gross calorific value among all fuels. However, the use of a suitable electron donor, in what so-called "photocatalytic reforming", is required to achieve acceptable efficiency. This oxidation half-reaction can be exploited to oxidize the dissolved organic pollutants, thus, simultaneously improving the water quality. Such pollutants would replace other potentially costly electron donors, achieving the dual-functionality purpose. Since the aromatic compounds are widely spread in the environment, they are considered attractive targets to apply this technology. In this review, different aspects are highlighted, including the employing of different polymorphs of pristine titanium dioxide as photocatalysts in the photocatalytic processes, also improving the photocatalytic activity of TiO2 by loading different types of metal co-catalysts, especially platinum nanoparticles, and comparing the effect of various loading methods of such metal co-catalysts. Finally, the photocatalytic reforming of aromatic compounds employing TiO2-based semiconductors is presented. [ABSTRACT FROM AUTHOR]

I Nanomaterials i was able to uphold its high standards for published papers due to the outstanding efforts of our reviewers. Regardless of whether the articles they examined were ultimately published, the editors would like to express their appreciation and thank the following reviewers for the time and dedication that they have shown I Nanomaterials i : The statements, opinions and data contained in all publications are solely those of the individual author(s) and contributor(s) and not of MDPI and/or the editor(s). Thanks to the efforts of our reviewers in 2022, the median time to first decision was 12.7 days and the median time to publication was 2.9 days. [Extracted from the article]

The work here deals with the observation of structural, optical and magnetic property of Eu2+ doped SnO2 nano particles. The structure is characterized by X-ray diffraction(XRD), transmission electron microscopy (TEM), Raman spectroscopy, UV–Vis absorption, photoluminescence (PL), and time resolved PL (TRPL) spectroscopy. The introduction of Eu affects the crystallite size and substitutes with Sn without showing any interstitial defect formation. With 1% doping as the limit for entering the crystal, the crystallite size shows expansion. Upon excitation at 400 nm, the presence of Eu2+ is approved with the absence of emission around 613 nm in the doped system. Decrease in the band gap with creation of sub-band gap states under doping is reported and with the increase in Eu2+ concentration, the increase in probability of transfer of nonradiative energy is observed. Further, magnetic properties are determined by investigating magnetization vs. applied fields. A ZFC–FC measurement for the system showing highest magnetization is also performed. To boot, the state of Eu2+ is also made confirmed with the observed EPR splitting at g = 1.88. Finally, a new approach through density functional theory has been carried out for quantitative and qualitative justifications. The minimum energy states have been computed by varying the internal positions of atoms under various defined parameters. The electronic states and density of states (DOS) behavior have been calculated for justified prediction of lattice sites and respective presence of atoms. The stable magnetic ground state has been estimated using the theoretical technique. [ABSTRACT FROM AUTHOR]

Rigorous peer-reviews are the basis of high-quality academic publishing. Thanks to the great efforts of our reviewers, I Materials i was able to maintain its standards for the high quality of its published papers. Thanks to the contribution of our reviewers, in 2021, the median time to first decision was 15 days and the median time to publication was 38 days. [Extracted from the article]

Abstract: Karrooite, MgTi2O5, is a promising ceramic pigment due to its high refractoriness and refractive indices, as well as its ability to host transition metal ions in two crystallographically distinct octahedral sites. The colouring performance was investigated combining X-ray powder diffraction with UV–vis–NIR spectroscopy on karrooite doped with V, Cr, Mn, Fe, Co or Ni (M) according to the formula Mg1− x Ti2− xM 2 x O5, with x=0.02 and 0.05. Transition metals solubility in the karrooite lattice is not complete and a second phase is always present (geikielite or rutile). Structural data proved that incorporation of different chromophore ions into the karrooite structure affects unit cell parameters, bond length distances and angles, site occupancies and therefore cation order–disorder. Optical spectra exhibit broad absorbance bands of Co(II), Cr(IV), Fe(III), Mn(II), Mn(III), Ni(II), V(IV) with distinct contributions by cations in the M 1 and M 2 sites. Karrooite pigments have colours ranging from orange to brown-tan (Cr, Fe, Mn, V) to green (Co) and yellow (Ni) that are stable in low-temperature (<1050°C) ceramic glazes and glassy coatings. [Copyright &y& Elsevier]