Search results for "GaP"

Unveiling the oxidation behavior of liquid-phase exfoliated antimony nanosheets

2020

Abstract Antimonene, a monolayer of β-antimony, is increasingly attracting considerable attention, more than that of other monoelemental two-dimensional materials, due to its intriguing physical and chemical properties. Under ambient conditions, antimonene exhibits a high thermodynamic stability and good structural integrity. Some theoretical calculations predicted that antimonene would have a high oxidation tendency. However, it remains poorly investigated from the experimental point of view. In this work, we study the oxidation behavior of antimonene nanosheets (ANS) prepared by ultrasonication-assisted liquid-phase exfoliation. Using a set of forefront analytical techniques, a clear effe…

ZnO nanorods covered with a TiO2 layer: simple sol–gel preparation, and optical, photocatalytic and photoelectrochemical properties

2015

In this work, composite core–shell ZnO/TiO2 materials were fabricated by deposition of TiO2 layers via a sol–gel method onto ZnO nanorods hydrothermally grown on an ITO electrode. Two approaches to the sol–gel procedure resulted in strongly different morphologies and thicknesses of the deposited TiO2 layer, as shown in electron microscopy studies. The decrease of the optical band gap energies of the ZnO/TiO2 composites by about 0.2–0.3 eV with respect to the TiO2 nanoparticles and ZnO nanorods was determined from UV-Vis diffuse reflectance spectra. The photocatalytic activities of the systems were determined by investigation of the decolorization of Methylene Blue (MB) in aqueous solution, …

GW190814: Spin and equation of state of a neutron star companion

2020

The recent discovery by LIGO/Virgo of a merging binary having a $\sim 23 M_\odot$ black hole and a $\sim 2.6 M_\odot$ compact companion has triggered a debate regarding the nature of the secondary, which falls into the so-called mass gap. Here we explore some consequences of the assumption that the secondary was a neutron star (NS). We show with concrete examples of heretofore viable equations of state (EOSs) that rapid uniform rotation may neither be necessary for some EOSs nor sufficient for others to explain the presence of a NS. Absolute upper limits for the maximum mass of a spherical NS derived from GW170817 already suggest that this unknown compact companion might be a slowly or even…

Dressed emitters as impurities

2021

Dressed states forming when quantum emitters or atoms couple to a photonic bath underpin a number of phenomena and applications, in particular dispersive effective interactions occurring within photonic bandgaps. Here, we present a compact formulation of the resolvent-based theory for calculating atom-photon dressed states built on the idea that the atom behaves as an effective impurity. This establishes an explicit connection with the standard impurity problem in condensed matter. Moreover, it allows us to formulate and settle in a model-independent context a number of properties previously known only for specific models or not entirely formalized. The framework is next extended to the cas…

Uzturs ar samazinātu ogļhidrātu saturu (SCD/GAPS) autiskā spektra simptomu mazināšanai bērniem- pilotpētījums

2019

Ar autismu saprot plaši izplatītus smadzeņu attīstības traucējumus, kuru etioloģijā būtiska ietekme ir gan vides, gan ģenētiskajiem faktoriem. Autisma izpausmes katram cilvēkam var būt ar individuālu simptomu kopumu, tāpēc biežāk runā par autiskā spektra traucējumiem (AST), ko raksturo simptomu triāde - problēmas integrēties sabiedrībā, komunikatīvie traucējumi un ierobežota, atkārtota uzvedība. Saskaņā ar CDC (Centers for Disease Control and Prevention) 2014. g. datiem ASV viens no 59 bērniem ir ar AST. Tiek vērtēts, ka Latvijā, tāpat kā Eiropā, ar AST ir katrs simtais bērns. Medicīniskajā literatūrā dominē viedoklis, ka šobrīd nav vienas terapijas, kas spētu mazināt AST pamatsimptomus. To…

Systematic trends in (0 0 1) surface ab initio calculations of ABO 3 perovskites

2018

This work was supported by the Latvian Council of Science Grant No. 374/2012 and the Latvian National Research Program IMIS2. Many stimulating discussions with D. Vanderbilt, K.M. Rabe, M. Rohlfing, E. Heifets, J. Maier, G. Borstel and E.A. Kotomin are greatly acknowledged.

Comparative Ab Initio Calculations of ReO3, SrZrO3, BaZrO3, PbZrO3 and CaZrO3 (001) Surfaces

2020

We performed, for first time, ab initio calculations for the ReO2-terminated ReO3 (001) surface and analyzed systematic trends in the ReO3, SrZrO3, BaZrO3, PbZrO3 and CaZrO3 (001) surfaces using first-principles calculations. According to the ab initio calculation results, all ReO3, SrZrO3, BaZrO3, PbZrO3 and CaZrO3 (001) surface upper-layer atoms relax inwards towards the crystal bulk, all second-layer atoms relax upwards and all third-layer atoms, again, relax inwards. The ReO2-terminated ReO3 and ZrO2-terminated SrZrO3, BaZrO3, PbZrO3 and CaZrO3 (001) surface band gaps at the &Gamma

Identification of passive layers on Co in Alkaline solutions by photocurrent spectroscopy

2005

The photoelectrochemical behavior of passive films on Co has been studied as a function of the polarizing voltage and electrolyte composition. Passive layers formed at 0 V (standard hydrogen electrode, SHE) in 0.1 M NaOH consisted of Co(OH) 2 , whose bandgap value has been found to be 1.85 eV. Higher bandgap values (2.75 eV) have been measured for passive films formed in borate buffer at 0 V (SHE), which are mainly consist of CoO. The Eg values have been related to the film composition on the basis of a correlation between the bandgap of passive films and the electronegativity of their constituents.

A semiempirical approach to the estimate of optical band gap in group-III nitrides alloys

2008

Multi-doped Brookite-Prevalent TiO2 Photocatalyst with Enhanced Activity in the Visible Light

2018

© 2018 Springer Science+Business Media, LLC, part of Springer Nature Abstract: Enabling solar and/or visible light-driven photocatalysis is a crucial step to access innovative applications in environmental science and sustainable energy. Titanium dioxide is the most used photocatalyst because of its low cost and toxicity, however it is also limitedly active under visible light irradiation due to its wide band gap. Among its polymorphs, brookite holds promising optoelectronic properties for visible light photocatalysis, which have to the best of our knowledge been limitedly exploited. Here, a C,S,N-doped brookite-based TiO2has been prepared via a rapid one-pot sol–gel synthesis. Besides subs…