Materiais óxidos magnéticos nanoestruturados

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Síntese de nanofios de óxidos semicondutores para aplicações em dispositivos ópticos e eletrônicos

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Sensores para sistemas líquidos diluídos combinando Raman amplificado em superfície (SERS) e língua eletrônica

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Desenvolvimento de eletrodos com materiais nanoestruturados para determinação de corantes de cabelo

Pós-graduação em Química - IQ

Unusual broadening of the NIR luminescence of Er3+-doped Nb2O5 nanocrystals embedded in silica host: Preparation and their structural and spectroscopic study for photonics applications

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Aplicações clássicas da técnica de espalhamento de raios-x a baixo ângulo em materiais nanoestruturados

The small angle X-ray scattering (SAXS) technique has been used with very much versatility and success in the structural characterization of nanostructured materials. The present work deals with a study of the principles of the SAXS technique and of some classical models employed in the structural characterization of nanostructured materials. Particularly, the study of the models and of the associated methodologies is applied to a set of samples of silica gels, of varied typical structures, prepared in the Laboratório de Novos Materiais of the Departamento de Física of the IGCE. The work discusses in an introductory chapter the principles of the SAXS technique and the foundation of classical models often used in the structural characterization of materials. The classical models and the associated methodologies were applied to a variety of silica gel structures. The studies include: i) the scattering from a system of particles - Guinier's law; ii) the asymptotic scattering from a two-phase system - Porod's law; iii) systematic deviation from Porod's law - Surface Fractal; iv) heterogeneities in solids with random size distribution - DAB Model; and v) the scattering from mass fractal structures. The analyses were carried out from experimental SAXS data obtained in several opportunities at the Laboratório Nacional de Luz Síncrotron (LNLS)

Obtenção de compósitos nanoestruturados PSU/nanotubos de carbono pela técnica de eletrofiação

The nanostructured materials over the last decade have been increasing the variety of studies and research applications in many industries. From the understanding and manipulation of nanoscale is possible to obtain high-performance materials. One method, which has been very effective in obtaining of nanostructured composites, is the electrospinning, a technique that uses electrostatic forces to produce fibers from a polymer solution. By understanding and controlling of process conditions, such as solution viscosity, working distance, the velocity of the collector, applied voltage and others conditions, it is possible to obtain fibers in many different morphologies. This work aims to obtain nanostructured composites from polysulfone (PSU) a thermoplastic polymer with high oxidation resistance and good mechanical strength at high temperatures and carbon nanotubes (CNTs) that are excellent reinforcements for polymer materials, their mechanical resistance is greater than that of all known materials; using the electrospinning process via polymer solution. Were used polysulfone solutions, n,n-ndimetil acetamide (PSU / DMAc) and this same solution added of CNTs in order to obtain the nanofibers. In both cases were analyzed the effectiveness of the process from the analysis of fiber diameters, rheological behavior and infrared spectroscopy. The results obtained confirmed the efficiency of the electrospinning process to obtain polymeric fibers

Obtenção e caracterização de compósitos nanoestruturados de poli(sulfeto de fenileno) reforçados com nanotubos de carbono

Pós-graduação em Engenharia Mecânica - FEG

Oxidação de carboidratos via catálise metálica não enzimática para aplicação em sensores

This work has main aim of is to propose the synthesis and characterization of nanostructured materials for oxidation of carbohydrates such as glucose, with non-enzymatic catalysis. The proposed pathway of synthesis of metal catalysts is the polyol method and techniques of physical characterization proposals for analysis of prepared catalyst pass through diffraction technique of ray-x (DRX), scanning electron microscopy (SEM) and Energy Dispersive Spectroscopy ray-x (EDX). Technical proposals for the electrochemical characterization of the synthesized catalysts are Cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The prospects of this work are compared by the catalytic activity of the sensor designed with non-enzymatic sensors and biosensors also known in the literature

Aplicação do sistema de biosusceptometria AC para monitoramento de nanopartículas magnéticas na circulação sanguínea

Pós-graduação em Biologia Geral e Aplicada - IBB

Nanopartículas de CeO2 modificadas com Er obtidas pelo método hidrotermal microondas: estudo fotoluminescente

The development of nanostructured materials have aroused great interest of the industries all over the country, since they enable the development of devices that can be used as gate insulators on silicon transistors, electrochromic devices, solid electrolyte oxygen sensors and as a photoluminescent materials . In this project, it is proposed to investigate the optical properties of CeO2 modified with rare earth Er processed in hydrothermal-microwave. The synthesis of one-dimensional nanostructures (1D) was measured from dilute aqueous solutions of acids and salts of starting reagents in the presence of chemical basis, after these aqueous solutions were processed on hydrothermal-microwave to particle growth. The particles obtained after processing were characterized by X-ray Diffraction, Rietveld Analysis and Raman Spectroscopy. The particle morphology was observed by scanning electron microscopy with field emission gun. The synthesis of 1D nanostructures are evaluated for different surfactants and starting precursors (ceria different salts), pH, temperature and pressure which can modify the morphology of the nanostructures. Combining laboratory experiments and theoretical calculations it was desired to understand the organization of the nanoparticles and their resulting structure. Strict control of chemical homogeneity, crystal structure, microstructure and interaction of the CeO2 cluster with different surfactants using the Hartree-Fock method, was intended to obtain properties compatible with their use in catalysts and optical devices. The use of mineralizer agent KOH and 8 minutes of processing time synthesis conditions were chosen to evaluate the effect of Er dopant. It has been proved that this doping with rare earth increases the photoluminescent properties of the compound obtained without change the structural and morphological propreties of ceria

Nanopartículas de CeO2 modificadas com Er obtidas pelo método hidrotermal microondas: estudo fotoluminescente

The development of nanostructured materials have aroused great interest of the industries all over the country, since they enable the development of devices that can be used as gate insulators on silicon transistors, electrochromic devices, solid electrolyte oxygen sensors and as a photoluminescent materials . In this project, it is proposed to investigate the optical properties of CeO2 modified with rare earth Er processed in hydrothermal-microwave. The synthesis of one-dimensional nanostructures (1D) was measured from dilute aqueous solutions of acids and salts of starting reagents in the presence of chemical basis, after these aqueous solutions were processed on hydrothermal-microwave to particle growth. The particles obtained after processing were characterized by X-ray Diffraction, Rietveld Analysis and Raman Spectroscopy. The particle morphology was observed by scanning electron microscopy with field emission gun. The synthesis of 1D nanostructures are evaluated for different surfactants and starting precursors (ceria different salts), pH, temperature and pressure which can modify the morphology of the nanostructures. Combining laboratory experiments and theoretical calculations it was desired to understand the organization of the nanoparticles and their resulting structure. Strict control of chemical homogeneity, crystal structure, microstructure and interaction of the CeO2 cluster with different surfactants using the Hartree-Fock method, was intended to obtain properties compatible with their use in catalysts and optical devices. The use of mineralizer agent KOH and 8 minutes of processing time synthesis conditions were chosen to evaluate the effect of Er dopant. It has been proved that this doping with rare earth increases the photoluminescent properties of the compound obtained without change the structural and morphological propreties of ceria

Synthesis and characterization of silver/alanine nanocomposites for radiation detection in medical applications: the influence of particle size on the detection properties

Silver/alanine nanocomposites with varying mass percentage of silver have been produced. The size of the silver nanoparticles seems to drive the formation of the nanocomposite, yielding a homogeneous dispersion of the silver nanoparticles in the alanine matrix or flocs of silver nanoparticles segregated from the alanine crystals. The alanine crystalline orientation is modified according to the particle size of the silver nanoparticles. Concerning a mass percentage of silver below 0.1%, the nanocomposites are homogeneous, and there is no particle aggregation. As the mass percentage of silver is increased, the system becomes unstable, and there is particle flocculation with subsequent segregation of the alanine crystals. The nanocomposites have been analyzed by transmission electron microscopy (TEM), UV-Vis absorption spectroscopy, X-ray diffraction (XRD), and Fourier transform infrared (FTIR) spectroscopy and they have been tested as radiation detectors by means of electron spin resonance (ESR) spectroscopy in order to detect the paramagnetic centers created by the radiation. In fact, the sensitivity of the radiation detectors is optimized in the case of systems containing small particles (30 nm) that are well dispersed in the alanine matrix. As the agglomeration increases, particle growth (up to 1.5 mu m) and segregation diminish the sensitivity. In conclusion, nanostructured materials can be used for optimization of alanine sensitivity, by taking into account the influence of the particles size of the silver nanoparticles on the detection properties of the alanine radiation detectors, thus contributing to the construction of small-sized detectors.

Highly stabilized alpha-NiCo(OH)(2) nanomaterials for high performance device application

Improving the charge capacity, electrochemical reversibility and stability of anode materials are main challenges for the development of Ni-based rechargeable batteries and devices. The combination of cobalt, as additive, and electrode material nanostructuration revealed a very promising approach for this purpose. The new alpha-NiCo mixed hydroxide based electrodes exhibited high specific charge/discharge capacity (355-714 C g(-1)) and outstanding structural stability, withstanding up to 700 redox cycles without any significant phase transformation, as confirmed by cyclic voltammetry, electrochemical quartz crystal microbalance and X-ray diffractometry. In short, the nanostructured alpha-NiCo mixed hydroxide materials possess superior electrochemical properties and stability, being strong candidates for application in high performance batteries and devices. (C) 2012 Elsevier B.V. All rights reserved.

Frequency upconversion properties of Tm3+ doped TeO2-ZnO glasses containing silver nanoparticles

Frequency upconversion (UC) properties of Tm3+ doped TeO2-ZnO glasses containing silver nanoparticles (NPs) were investigated. Infrared-to-visible and infrared-to-infrared UC processes associated to the Tm3+ ions were studied by exciting the samples with a cw 1050 nm ytterbium laser. The luminescence intensity as a function of laser intensity was also measured using a pulsed 1047 nm Nd3+:YVO laser in order to determine the number of photons participating in the UC processes. Enhancement of the UC signals for samples heat-treated during various time intervals is attributed to the growth of the local field in the vicinity of the NPs. PL enhancement by one-order of magnitude was observed in the whole spectrum of the samples heat-treated during 48 h. On the other hand PL quenching was observed for the samples heat-treated more than 48 h. (c) 2011 Elsevier B.V. All rights reserved.