Submitted by Caroline Xavier (caroline.xavier@pucrs.br) on 2017-06-30T18:08:55Z No. of bitstreams: 1 DIS_DANIELI_BORN_GUERRA_COMPLETO.pdf: 6232841 bytes, checksum: 6cce70184509f5204d1a506262b6559b (MD5) / Made available in DSpace on 2017-06-30T18:08:55Z (GMT). No. of bitstreams: 1 DIS_DANIELI_BORN_GUERRA_COMPLETO.pdf: 6232841 bytes, checksum: 6cce70184509f5204d1a506262b6559b (MD5) Previous issue date: 2017-03-30 / In this work, we investigated the effects of ion implantation and irradiation on the structure and morphology of Bi e Bi2+xTe3-y nanowires exposed to Au and Cu beams with energies ranging from 30 keV to 1 MeV. The wires were grown by template-assisted electrodeposition with diameters of 30, 100 and 130 nm. Bi-rich compounds are obtained at -200 mV using an Ag/AgCl reference electrode. Almost stoichiometric nanowires are obtained at 0 mV vs Ag/AgCl. XRD measurements revealed a polycrystalline structure, with a strong peak in the planes (0 1 5) for Bi-rich wires and a preferential diffraction (1 1 0) for the Te-rich compounds. The dark field TEM analyzes indicates an influence of the nanochannel geometry on the grain size of nanowires. The irradiation parameters were selected based on simulations from SRIM and Iradina programs. The irradiations were performed with the wires deposited in transmission electron microscopy (TEM) grids. The irradiated nanowires presented different morphologies, depending on the irradiation conditions, sometimes presenting a ?wavy? morphology. Cu irradiations did not cause significant modifications in the crystalline structure of the samples. For samples irradiated with Au, TEM analysis revealed an amorphized structure, containing an embedded dispersion of small spherical crystallites. Besides, a distribution of nanoparticles dispersed in the vicinity of the irradiated wires was seen on the TEM grids, formed most probably from material redepositing due to sputtering. The 400 keV and 1 MeV Au ions have comparable stopping powers. However, for irradiations at 1 MeV the material underwent a greater erosion process, resulting in the formation of holes through the wires. / Neste trabalho, investigamos os efeitos de implanta??o e irradia??o i?nica na estrutura e morfologia de nanofios de Bi e Bi2+xTe3-y expostos a feixes de Au e Cu com energias que variam de 30 keV a 1 MeV. Os fios foram crescidos por eletrodeposi??o no modo template assisted com di?metros de 30, 100 e 130 nm. Compostos ricos em Bi s?o obtidos a -200 mV em rela??o a um el?trodo de refer?ncia de Ag/AgCl. Nanofios quase estequiom?tricos s?o obtidos a 0 mV vs. Ag/AgCl. As medidas DRX revelaram uma estrutura policristalina, com um forte pico dos planos (0 1 5) para fios ricos em Bi e uma difra??o preferencial (1 1 0) para os compostos ricos em Te. As an?lises de campo escuro de TEM indicam uma influ?ncia da geometria dos nanocanais no tamanho de gr?o do nanofio. Os par?metros de irradia??o foram selecionados com base em simula??es dos programas SRIM e Iradina. As irradia??es foram realizadas com os fios depositados em grades de microscopia eletr?nica de transmiss?o (TEM). Os nanofios irradiados apresentaram diferentes morfologias, dependendo das condi??es de irradia??o, podendo adquirir uma superf?cie "ondulada". As irradia??es realizadas com feixes de Cu n?o causaram modifica??es significativas na estrutura cristalina das amostras. Para as amostras irradiadas com Au. Observa??es de TEM revelam uma dispers?o de pequenos cristalitos esf?ricos embutidos em uma estrutura amorfizada. Al?m disso, uma distribui??o de nanopart?culas na vizinhan?a dos fios irradiados tamb?m foi observada nas grades TEM, provavelmente formada por redeposi??o de material devido ao sputtering. Ainda que os ?ons de Au de 400 keV e 1 MeV depositem valores de energia compar?veis, para irradia??es a 1 MeV o material sofreu um processo de eros?o maior, resultando na forma??o de furos atrav?s dos fios.

Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2017-04-03T19:41:30Z No. of bitstreams: 1 ArthurFelipeDeFariasMonteiro_DISSERT.pdf: 6373857 bytes, checksum: d6418f0c51f873b10d6e15be186817d7 (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2017-04-05T19:01:11Z (GMT) No. of bitstreams: 1 ArthurFelipeDeFariasMonteiro_DISSERT.pdf: 6373857 bytes, checksum: d6418f0c51f873b10d6e15be186817d7 (MD5) / Made available in DSpace on 2017-04-05T19:01:11Z (GMT). No. of bitstreams: 1 ArthurFelipeDeFariasMonteiro_DISSERT.pdf: 6373857 bytes, checksum: d6418f0c51f873b10d6e15be186817d7 (MD5) Previous issue date: 2016-04-15 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico (CNPq) / As Redes Metalorg?nicas (Metal Organic Frameworks ? MOF?s) s?o materiais h?bridos, geralmente cristalinos, constitu?dos por ?tomos ou clusters met?licos, coordenados ? ligantes org?nicos polifuncionais, geralmente, observando-se a presen?a de poros/canais de dimens?es nanom?tricas. Suas estruturas s?o de baixa densidade em fun??o da porosidade, e apresentam alta ?rea superficial, bem como um grande volume de poro, o que ?s levam a lugar de destaque do ponto vista cient?fico-tecnol?gico, sendo aplic?veis na cat?lise, adsor??o, separa??o, estocagem de gases, entrega de f?rmacos, etc. Cu-MOF?s foram sintetizadas via m?todo eletroqu?mico a partir de dois ligantes distintos, 1,3-H2BDC e 1,4-H2BDC. Os par?metros sint?ticos empregados, tais como, meio reacional (raz?o H2O/DMF), diferen?a de potencial e corrente el?trica, foram avaliados e sua influ?ncia sobre a estrutura cristalina determinada. Os materiais foram obtidos em uma hora, sugerindo que esta ? uma rota cineticamente vantajosa para a obten??o de redes metalorg?nicas de cobre. O produto da s?ntese da rede Cu(1,4-BDC) ? composto de duas estruturas cristalinas lamelares (em camadas) e microporosas. A cristaliza??o destas diferentes estruturas est? diretamente relacionada ao valor de corrente el?trica empregada. As duas estruturas se diferenciam basicamente pelo deslocamento entre camadas consecutivas, 60? e 120?, respectivamente. O deslocamento das camadas resultou em estruturas com diferentes volumes de canais, sendo a estrutura com deslocamento de 60? a que apresenta canais com maior volume, mais indicado para a adsor??o. Essa estrutura, denominada Cu(1,4-BDC) 2, foi aplicada na adsor??o de azul de metileno, sendo avaliadas as influ?ncias de pH, temperatura e concentra??o. Observou-se que valores de pH entre 5,0 e 6,0 promovem uma melhor adsor??o. Diferentes condi??es foram testadas, tais como concentra??es entre 25 e 250 mg/L e temperaturas entre 293,15 e 313,15 K. Adicionalmente, tamb?m foram avaliados fatores cin?ticos, termodin?micos e de equil?brio para a adsor??o. Constatou-se que o modelo cin?tico de pseudo-segunda ordem ? o mais compat?vel com o processo. Para os fatores termodin?micos, verificou-se que o processo ? exot?rmico, espont?neo e com maior efici?ncia ? uma temperatura de 293,15 K. Foram testados dois modelos de isotermas, o de Langmuir e o de Freundlich, sendo o modelo de Langmuir o que apresentou maior compatibilidade, prognosticando uma capacidade adsortiva m?xima te?rica de 76,63 ?mol/g, sendo que para as condi??es otimizadas (14 horas), a capacidade experimentalmente obtida foi de 75,91 ?mol/g, (99,06% do valor te?rico). Foram realizados ensaios de reuso do material, onde foi constatada uma efici?ncia superior ? 60% para at? quatro ciclos de adsor??o/dessor??o. / The metal organic frameworks (MOF's) are hybrid materials, generally crystalline, consisting of metallic atoms or metallic clusters, coordinated to polyfunctional organic ligands, generally observing the presence of pores/channels in nanometer dimensions. Their structures shows low density due to the porosity, have high surface area and a high pore volume, which lead to the prominent place of scientific-technological area, applicable in various fields as catalysis, adsorption, separation, gases storage, drug delivery, etc. Cu-MOFs were synthesized by the electrochemical method, using the 1,3-H2BDC and 1,4-H2BDC linkers in different H2O/DMF solvent proportions. The influence of electrochemical variables of process, such as voltage and electric current, and their influence on the final structure of the material was examined. The materials were obtained within one hour, showing that this method is kinetically advantageous for the preparation of the copper network. The product of the synthesis of Cu (1,4-BDC) network is composed of two lamellar (layered) and microporous crystalline structures. The formation of different structures are directly relate to the electrical current condition imposed on the synthesis. The two structures differ mainly by the displacement between subsequent layers, 60? and 120?, respectively. The displacement of the layers resulted in structures with different channels volumes, where the structure with 60? of displacement presents channels with greater volume, what may be applicable in adsorption. This structure, called Cu(1,4-BDC)2, was applied for the blue methylene adsorption, where the study of the influence of pH, temperature and concentration was performed. It revealed that for pH values between 5.0 and 6.0 there is an increased amount of the adsorbed dye. Different conditions were tested, such as concentrations between 25 and 250 mg/L and temperatures between 293.15 and 313.15 K. Varying concentrations of the dye solution, the kinetic factors, thermodynamic and equilibrium for adsorption, were evaluated. It was find that the kinetic model of pseudo-second order is the most compatible with the process. For the thermodynamic factors, it was find that the process is exothermic, spontaneous and has the highest efficiency at 293.15 K. Two models were tested for adsorption isotherm, the Langmuir and Freundlich, and the most compatible with the data was the Langmuir model, theoretically predicting a maximum adsorption capacity of 76.63 ?mol/g, and for the optimized conditions (14 hours), the capacity obtained experimentally was 75.91 ?mol/g, (99.06% theoretical). Reuse tests of the material were carried out and it was found that the material can reach the reuse efficiencies higher than 60% for up to four adsorption/desorption recycles.