Orientador: Rafael Zadorosny / Resumo: Neste trabalho é apresentada a produção de condutores revestidos de material supercondutor (superconducting coated conductors – SCC), ou seja, um filme supercondutor cerâmico, obtido por impressão direta da solução precursora sobre um substrato. Este processo foi estudado com o intuito de aplicar uma técnica de fabricação simples e de baixo custo visando a obtenção de filmes de boa qualidade a um custo reduzido. As soluções precursoras de CeO2, BSCCO e YBCO foram obtidas pelo método Pechini, considerada uma rota de produção de baixo custo. A fim de comparar a impressão direta com outra técnica, foram produzidos os mesmos filmes por spin coating. Para se obter os SCC, foi adicionada Ag às soluções dos materiais cerâmicos verificando sua incorporação na estrutura do filme e não apenas como um material de revestimento (como ocorre com as fitas supercondutoras de segunda geração). As caracterizações morfológicas e estruturais foram realizadas para identificar e analisar o processo de impressão direta do SCC. Já o comportamento supercondutor do material foi verificado através de medidas de R x T. / Abstract: This work presents the production of superconducting coated conductors (SCC), that is, a superconducting ceramic film obtained by direct printing of the precursor solution on a substrate. This process was studied with the intention of applying a simple and low cost technique focusing in the obtaining of good quality films at a reduced cost. The precursor solutions of CeO2, BSCCO and YBCO were obtained by the Pechini method, also considered a low cost production route. In order to compare direct printing with another technique, the same films were produced by spin coating. In order to obtain the SCC's, Ag was added to the solutions of the ceramic materials to incorporate in the film structure and not just as a coating material (as with second-generation superconducting tapes). Morphological and structural characterizations were performed to identify and analyze the SCC obtained by direct printing process. The superconductive behavior of the material was verified by measurements of R x T. / Doutor

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Two methods of dielectric characterization are presented that offer quick and cost-effective solutions for screening complex dielectric material properties. Through Direct-Print Additive Manufacturing (DPAM) methods, a dielectric material of choice is dispensed into a capacitor structure and characterized through 1-port s-parameter measurements. The presented methods use fixtures that are modeled and validated through simulation then implemented in practice. Advanced simulations are performed to gain insights which are used to optimize the dielectric characterization performance of the fixtures. Additional investigations are performed which investigate the durability of the fixture and material within by exposing the combination to rough environmental conditions for an extended duration. The presented capacitor structures are investigated to characterize dielectric materials within the bandwidth of 0.1-15 GHz, saving the time and effort required in using multiple dielectric characterization methods that cover the same bandwidth. Both methods are compared based on the results for each method achieved in practice while considering the process required perform each method. The pros and cons of the presented characterization methods are weighed which highlights the key aspects for successfully characterizing dielectric materials with each method as well as revealing the potential limitations associated with each.

Square open loop resonator (SOLR) bandpass filters fabricated with additive manufacturing techniques are presented and studied. One filter contains novel 3D capacitive plates used to enhance resonator coupling. The filters are centered at 2.45 GHz and loaded with capacitors for miniaturization as low as 21% that of a conventional SOLR bandpass filter. The pass-band insertion loss of the filters ranges from 3.8 dB to 5.5 dB and the 3 dB bandwidth ranges from 180 MHz to 250 MHz. Also, degradation in the effective conductivity of printed ink as a function of substrate roughness is analyzed. Finally, a study of dielectric and metallic 3D printing processes that are candidates for digital manufacturing of integrated mobile phone client antennas is presented.

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