The bio-enabled syntheses of functional nano-structured metal oxide thin films is of importance for a range of applications, in photonics, electronics, sensing, cell engineering, and biochemical devices. This type of novel syntheses method can overcome problems common in conventional oxide processing. In general, conventional oxide processes often require thermal treatment, caustic chemicals, and mechanical processing when producing shape-controlled inorganic materials. In contrast, biological processes are usually carried out under mild conditions (low temperature, neutral pH, and atmospheric pressure) and are therefore promising for the development of benign processes. Functional materials synthesized at room temperature using biomolecules are promising due to their expediency. During recent years, significant discoveries and progress have been made in discovering, and finding new applications for such biomimetic oxide-based minerals. However, much of the research has focused on SiO- and TiO-bearing organic-inorganic hybrid materials, of which a significant limitation is that, there are relatively few water-soluble inorganic oxide precursors commercially available for such biological syntheses. Two common compounds that are used in the biomimetic syntheses of SiO₂ and TiO₂ are tetramethoxisilane (TMOS) and Ti(IV) -bis(ammonium lactato) dihydroxide ( TiBALDH ). As a result, approaches to synthesize new water-soluble transitional metal complexes for use as precursors in the biomineralization of the corresponding functional metal oxide thin films were explored in this work, in order to expand the range of functional oxide chemistries formed via bio-enabled methods. A Ti-containing compound was synthesized to compare the behavior of commercially-available and as-synthesized TiBALDH. Another titanium-containing complex with citrate ligands, instead of lactate, was also synthesized to investigate the influence of the ligand type on the deposition behavior of the precursors. Zirconium- and hafnium-containing complexes were also synthesized to demonstrate the feasibility and versatility of the idea of applying bio-enabled syntheses to the fabrication of functional mineral oxides other than the reported SiO₂ and TiO₂. The second part of this thesis focuses on developing a novel way to fabricate porous functional mineral oxide thin films with controlled pore size, which can be used in a variety of applications, such as dye loading for optical, photochemical, or electrochemical purposes. Commercially-available, carboxyl-group-terminated polystyrene spheres of different sizes were utilized as pore-size controllers in the bio-enabled syntheses of TiO₂ by protamine. This approach has been found to be an effective means of creating uniform pores in inorganic mineral oxide coatings. The accomplishments of this work have the potential to be integrated so as to expand the boundaries of biomineralization in materials science and engineering fields.

Submitted by Fernanda Rodrigues de Lima (fernanda.rlima@ufpe.br) on 2018-07-11T19:41:35Z No. of bitstreams: 2 license_rdf: 811 bytes, checksum: e39d27027a6cc9cb039ad269a5db8e34 (MD5) DISSERTAÇÃO Bruna de Souza Constantino.pdf: 14899698 bytes, checksum: dbb7503da8d7f9c6e978fb27870941f9 (MD5) / Approved for entry into archive by Alice Araujo (alice.caraujo@ufpe.br) on 2018-07-18T18:12:55Z (GMT) No. of bitstreams: 2 license_rdf: 811 bytes, checksum: e39d27027a6cc9cb039ad269a5db8e34 (MD5) DISSERTAÇÃO Bruna de Souza Constantino.pdf: 14899698 bytes, checksum: dbb7503da8d7f9c6e978fb27870941f9 (MD5) / Made available in DSpace on 2018-07-18T18:12:55Z (GMT). No. of bitstreams: 2 license_rdf: 811 bytes, checksum: e39d27027a6cc9cb039ad269a5db8e34 (MD5) DISSERTAÇÃO Bruna de Souza Constantino.pdf: 14899698 bytes, checksum: dbb7503da8d7f9c6e978fb27870941f9 (MD5) Previous issue date: 2017-02-23 / FACEPE / A atual configuração energética brasileira e mundial é fortemente dependente de fontes provenientes do petróleo. No entanto, devido à composição do petróleo cru e suas condições de produção, os equipamentos responsáveis pelo seu armazenamento e transporte são vitimados por agressões corrosivas. Problemas gerados direta ou indiretamente pela corrosão representam uma grande parcela dos custos totais para as empresas produtoras de petróleo e gás. Deste modo, revestimentos cerâmicos aplicados por meio de aspersão térmica hipersônico estão sendo estudados, visando aplicações como proteção contra a corrosão em matrizes metálicas da indústria petrolífera e que devem apresentar boas características de estabilidade química, resistência à corrosão e resistência a altas temperaturas. Neste trabalho foram estudadas cerâmicas produzidas a partir dos óxidos cerâmicos Al₂O₃ – ZrO₂ La₂O₃, onde foram fixados 2% (em massa) de Lantânia e adicionados 10%, 15% e 20% de Zircônia numa matriz de Alumina. Os pós cerâmicos foram pesados, misturados em moinho de bolas, compactados em prensa uniaxial e sinterizados em um dos três ciclos térmicos diferentes – 1350ºC, 1500ºC e 1650ºC. Assim, foram obtidas 09 amostras diferentes. Foram utilizadas na caracterização dos materiais as técnicas de: Análise de Tamanho de Partículas (ATP), Microscopia Ótica (MO), Microscopia Eletrônica de Varredura (MEV), Espectrometria de Energia Dispersiva (EDS), Microdureza Vickers e Difração de Raios-X (DRX). As amostras tiveram sua estabilidade analisada após 90 dias de imersão continua em petróleo cru provenientes de poços de origem de mar e de terra do estado de Sergipe. As avaliações da estabilidade das cerâmicas indicam que todas as amostras estudadas apresentaram uma boa resposta após a imersão em petróleo cru, no entanto, quanto às propriedades mecânicas, as cerâmicas sinterizadas a 1650ºC se destacam. / The current Brazilian and world energy configuration is strongly dependent on sources from the oil. However, due to the composition of the crude oil and production conditions, equipment for its storage and transport are victimized by corrosive attacks. Problems generated directly or indirectly by corrosion represent a large portion of the total costs to the oil and gas producing companies. Thus, ceramic tiles applied through spraying hypersonic heat are being studied, aimed at applications such as protection against corrosion in metallic arrays of the oil industry and that must be chemically stable and resistant to corrosion and high temperatures. This work studied ceramics produced from ceramic oxides Al₂O₃ – ZrO₂ La₂O₃, where were fixed 2% (by mass) of Lantania and added 10%, 15% and 20% of a Zirconia in an Alumina matrix. Ceramic powders produced by mixing in ball mill, compressed in an uniaxial press and sintered in one of the three different thermal cycles – 1350ºC, 1500ºC e 1650ºC, obtaining 09 different samples. Were used in the characterization of materials techniques of: particle size analysis (PSA), optical microscopy (OM), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), Vickers micro hardness and x-ray Diffraction (XRD). The samples had their stability analyzed after 90 days of continues immersion on crude oil from source wells of sea and land of the Sergipe. The stability evaluation of the ceramics indicates that all the studied samples presented a good response after the immersion in crude oil however, regarding the mechanical properties, the ceramics sintered at 1650ºC stand out.

Dizertační práce se zabývá problematikou výpočtu vlivu coulombovských interakcí částic na parametry emitovaného elektronového svazku v blízkosti Schottkyho a studené katody. Práce poskytuje základní předhled o problematice, popisuje vytvořené modely emisních zdrojů a metodu simulace Monte Carlo. Představuje novou metodu generování vstupních dat, která klade větší důraz na přesnou simulaci emisního procesu. Pozornost je zde věnována zejména vlivu interakcí na energiovou šířku, velikost virtuálního zdroje a jas katody v závislosti na velikosti poloměru hrotu a emisním proudu. Sledováním vývoje energiové šířky bylo zjištěno, že naprostá většina interakcí se odehrává v prostoru do několika mikrometrů od hrotu katody. Závislost spočtené celkové energiové šířky na úhlové intenzitě je ve shodě s dostupnými experimentálními daty. Spočtené energiové rozšíření vlivem coulombovských interakcí bylo srovnáno s hodnotami vypočtenými pomocí vzorců založených na analytických přiblíženích. Bylo zjištěno, že některé z nich přijatelně předpovídají trendy ale nemohou být použity pro kvantitativní odhad.