Encontrados 15 documentos, a visualizar página 1 de 2
Copper(II)imida-salen complexes encapsulated into NaY zeolite for oxidations re...
Kuźniarska-Biernacka, Iwona; Carvalho, M. Alice; Rasmussen, Soren B.; Bañares, Miguel A.; Biernacki, Krzysztof; Magalhães, A.; Rolo, Anabela G.Oxidation of phenol, cychohexanol and hydroquinone has been screened in the presence of copper(II) complexes with Schiff base Salen ligand, 1,5-bis{[(1E)-(2-hydroxyphenyl)methylene]amino}-1H-imidazole-4-carbonitrile, and encapsulated in the zeolite NaY using two different methods (A and B). The new heterogeneous catalysts were characterized by SEM, XRD, FTIR, EPR, Raman and chemical analysis. The structure of t...
Resonant raman scattering in ZnO : Mn and ZnO: Mn : Al thin films grown by RF s...
Cerqueira, M. F.; Vasilevskiy, Mikhail; Oliveira, F.; Rolo, Anabela G.; Viseu, T. M. R.; Campos, J. Ayres de; Alves, E.; Correia, RosárioRaman spectroscopy results obtained under visible (non-resonant) and UV (resonant) excitation for nanocrystalline ZnO, ZnO:Mn and ZnO:Mn:Al thin films grown by radio frequency magnetron sputtering are presented and compared. The origin of the multiple longitudinal optical (LO) phonon Raman peaks, strongly enhanced under resonance conditions, and the effects of the dopants on them are discussed in the framework ...
Low-temperature fabrication of layered self organized ge clusters by RF-sputtering
Pinto, S. R. C.; Rolo, Anabela G.; Buljan, M.; Chahboun, A.; Bernstorff, S.; Barradas, N. P.; Alves, E.; Kashtiban, R. J.; Bangert, U.; Gomes, M. J. M.In this article, we present an investigation of (Ge + SiO2)/SiO2 multilayers deposited by magnetron sputtering and subsequently annealed at different temperatures. The structural properties were investigated by transmission electron microscopy, grazing incidence small angles X-ray scattering, Rutherford backscattering spectrometry, Raman, and X-ray photoelectron spectroscopies. We show a formation of self-assem...
A microscopy study of germanium nanoparticules produced by pulsed laser deposition
Martín-Sánchez, J.; Marques, L.; Pinto, S. R. C.; Vieira, E. M. F.; Rolo, Anabela G.; Chahboun, A.; Ramos, Marta M. D.; Gomes, M. J. M.Comunicação oral ; Semiconductor nanoparticles (NPs) are of great interest for multiple applications in the fields of photonics, optoelectronics, photovoltaics and biomedicine [1]. The ability to manage properly the size distribution and density in the fabrication process is of crucial relevance. In the literature, it can be found a large number of strategies for NPs production, including physical vapour depos...
Ge nanoparticles produced by Pulsed Laser Deposition: morphological, structural...
Martín-Sánchez, J.; Marques, L.; Pinto, S. R. C.; Vieira, E. M. F.; Rolo, Anabela G.; Chahboun, A.; Ramos, Marta M. D.; Senra, Rosalía; Toudert, JohannApresentação em poster ; Semiconductor nanometer-sized particles (nanoparticles, NPs) have been widely investigated due to their unique size dependent properties. The interest in Ge NPs is recently increasing because of their interesting physical properties such as large carrier mobility, large Bohr exciton radius and near-direct band gap that are suitable for the development of advanced optoelectronic devices...
Room temperature paramagnetism of ZnO:Mn films grown by RF-sputtering
Oliveira, Filipe André; Cerqueira, M. F.; Vasilevskiy, Mikhail; Viseu, T. M. R.; Campos, J. Ayres de; Rolo, Anabela G.; Martins, J. S.; Sobolev, N. A.ZnO:Mn transparent thin films (thickness b1 μm) with the Mn contents ranging from 1.8 to 3.25 at.% were grown by RF magnetron co-sputtering. The films are nanocrystalline, with wurtzite-structure grains of a typical size of 20 nm and with a preferential orientation of the c-axis perpendicular to the surface. According to the Raman spectroscopy data, Mn mostly substitutes Zn in the lattice sites. In spite of the...
Raman study of doped-ZnO thin films
Cerqueira, M. F.; Rolo, Anabela G.; Viseu, T. M. R.; Campos, J. Ayres de; Arôso, T. de Lacerda; Oliveira, F.; Vasilevskiy, Mikhail; Alves, E.A Raman spectroscopy study of doped versus undoped ZnO layers is presented. The layers were grown by RF magnetron sputtering and the doping with Al, Sb and Mn was achieved by ion implantation with subsequent annealing. First-order Raman response measured under λ=488 nm excitation is discussed. It is shown that doping with any of the impurities used in this work produces a strong enhancement of the longitudinal ...
Electrical and raman scattering studies of ZnO:P and ZnO:Sb thin films
Campos, J. Ayres de; Viseu, T. M. R.; Barradas, N. P.; Alves, E.; Lacerda-Arôso, T. de Lacerda; Cerqueira, M. F.; Rolo, Anabela G.A study on the structure, electrical and optical properties of ZnO thin films produced by r.f. magnetron sputtering and implanted either with phosphorous (P) or antimony (Sb) is reported in this work. Raman spectroscopy, X-ray diffraction, optical transmittance and Hall effect measurements have been employed to characterize the samples. X-ray diffraction and Raman scattering patterns confirm that, after a 500ºC...
Structural and photoluminescence studies of erbium implanted nanocrystalline si...
Cerqueira, M. F.; Alpuim, P.; Filonovich, Sergey; Alves, E.; Rolo, Anabela G.; Andrês, G.; Soares, J.; Kozanecki, A.Hydrogenated amorphous and nanocrystalline silicon thin films deposited by Hot Wire (HW) and Radio-Frequency Plasma-Enhanced (RF) Chemical Vapor Deposition were Er-bium-implanted. Their pre-implantation structural properties and post-implantation optical properties were studied and cor-related. After one-hour annealing at 150ºC in nitrogen atmos-phere only amorphous films showed photoluminescence (PL) activity ...
ZnO thin films implanted with Al, Sb and P : optical, structural and electrical...
Viseu, T. M. R.; Campos, J. Ayres de; Rolo, Anabela G.; Arôso, T. de Lacerda; Cerqueira, M. F.; Alves, E.In this work we report a study on the structure, optical and electrical properties of P, Sb and Al implanted ZnO thin films that had been produced by r.f. magnetron sputtering. The influence of the different replacing atoms on the structure and properties of the films has been explored. Looking for the best annealing conditions, two different annealing temperatures (300ºC and 500ºC) have been employed. Raman sp...
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