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@PhDThesis{Ara˙jo:2018:TrCaRe,
               author = "Ara{\'u}jo, Michel Felipe Lima de",
                title = "Tratamento de cavidades reentrantes de ni{\'o}bio via 
                         implanta{\c{c}}{\~a}o i{\^o}nica por imers{\~a}o em plasma de 
                         nitrog{\^e}nio para o detector de ondas gravitacionais Mario 
                         Schenberg",
               school = "Instituto Nacional de Pesquisas Espaciais (INPE)",
                 year = "2018",
              address = "S{\~a}o Jos{\'e} dos Campos",
                month = "2018-07-26",
             keywords = "cavidades supercondutoras, implanta{\c{c}}{\~a}o i{\^o}nica, 
                         fator de qualidade, uperconducting cavities, ion implantation, 
                         quality factor.",
             abstract = "Cavidades supercondutoras de ni{\'o}bio, usadas como parte dos 
                         transdutores param{\'e}tricos do detector de ondas gravitacionais 
                         Mario Schenberg, foram tratadas pelo m{\'e}todo de 
                         implanta{\c{c}}{\~a}o i{\^o}nica por imers{\~a}o em plasma em 
                         alta temperatura (3IP-AT). O objetivo final {\'e} o de aumentar 
                         os respectivos valores dos fatores de qualidade el{\'e}tricos 
                         (Qe) implicando no aumento da sensibilidade do detector. 
                         Inicialmente, as implanta{\c{c}}{\~o}es se deram em amostras de 
                         ni{\'o}bio sob distintas condi{\c{c}}{\~o}es experimentais, 
                         variando-se par{\^a}metros como: temperatura das amostras, tempo 
                         de tratamento, energia/dura{\c{c}}{\~a}o/frequ{\^e}ncia dos 
                         pulsos de alta tens{\~a}o negativa. Procedimentos de limpeza da 
                         superf{\'{\i}}cie p{\'o}s-implanta{\c{c}}{\~a}o envolvendo 
                         descarga luminescente de arg{\^o}nio e/ou ataques 
                         qu{\'{\i}}micos foram avaliados quanto a sua efetividade para 
                         eliminar impurezas das amostras. Elas foram caracterizadas quanto 
                         {\`a} morfologia, forma{\c{c}}{\~a}o de fases e perfil de 
                         concentra{\c{c}}{\~a}o at{\^o}mica dos elementos presentes na 
                         superf{\'{\i}}cie. Tais caracteriza{\c{c}}{\~o}es foram 
                         imprescind{\'{\i}}veis para nortear a escolha de par{\^a}metros 
                         da implanta{\c{c}}{\~a}o de nitrog{\^e}nio para serem 
                         replicados nas cavidades ressonantes. Buscou-se formar camada 
                         supercondutora de nitreto de ni{\'o}bio na superf{\'{\i}}cie do 
                         metal, mas a utiliza{\c{c}}{\~a}o do 3IP-AT corroborou 
                         tamb{\'e}m para {\`a} co-forma{\c{c}}{\~a}o de fases n{\~a}o 
                         supercondutoras. Entretanto, foram obtidos aumentos nos valores de 
                         Qe de at{\'e} duas ordens de grandeza para cavidades implantadas 
                         em compara{\c{c}}{\~a}o com as que n{\~a}o sofreram 
                         implanta{\c{c}}{\~a}o i{\^o}nica de nitrog{\^e}nio. Notouse 
                         que os maiores valores de Qe foram alcan{\c{c}}ados para 
                         par{\^a}metros de tratamento que propiciassem a 
                         forma{\c{c}}{\~a}o da fase Nb-N, em que o nitrog{\^e}nio, em 
                         baixas concentra{\c{c}}{\~o}es at{\^o}micas, encontra-se 
                         dissolvido no ni{\'o}bio, formando solu{\c{c}}{\~a}o 
                         s{\'o}lida e ocupando posi{\c{c}}{\~a}o intersticial na rede 
                         cristalina. Esta pesquisa corrobora hip{\'o}teses levantadas por 
                         estudos recentes envolvendo o tratamento de cavidades de 
                         ni{\'o}bio utilizadas em aceleradores de part{\'{\i}}culas. 
                         ABSTRACT: Niobium superconducting cavities, used as part of the 
                         parametric transducers for Mario Schenberg gravitational wave 
                         detector, were treated via high temperature nitrogen plasma 
                         immersion ion implantation (3IPAT). The main objective is to 
                         increase the respective values of the electrical quality factors 
                         (Qe) - implying the increase of the sensitivity of the detector. 
                         Initially, the implantations were performed in niobium samples 
                         under different experimental conditions, varying some parameters 
                         such as: sample temperature, treatment time, energy / duration / 
                         frequency of negative high voltage pulses. Post-implantation 
                         surface cleaning procedures which involves glow argon discharge 
                         and / or chemical attacks were evaluated for their effectiveness 
                         in removing impurities from samples. They were characterized by 
                         means of their morphology, phase formation and the atomic 
                         concentration profiles of the elements present on the very near 
                         surfaces. Such characterizations were essential to guide the 
                         choice of nitrogen implantation parameters to be replicated in the 
                         resonant cavities. As a first step, it was sought to form niobium 
                         nitride superconducting layer on the metal surface, but the 3IP-AT 
                         process proved to be ineffective for this purpose due to the 
                         coformation of undesirable non-superconducting phase formation. 
                         Nevertheless, increases in Qe values of up to two orders of 
                         magnitude were obtained for implanted cavities in comparison with 
                         untreated ones. It was observed that the higher Qe-factors were 
                         reached for treatment parameters that favored the formation of the 
                         Nb-N phase, in which nitrogen, in low atomic concentrations, is 
                         dissolved in the niobium surface, forming a solid solution and 
                         occupying an interstitial position in the crystal lattice. The 
                         hypotheses raised in this research are in accordance with the 
                         findings reported in recent studies for RF superconducting 
                         cavities used in particle accelerators.",
            committee = "Oliveira, Rog{\'e}rio de Moraes (presidente/orientador) and 
                         Mello, Carina Barros (orientadora) and Mineiro, S{\'e}rgio Luiz 
                         and Berni, Luiz Angelo",
         englishtitle = "Treatment of reinforcing cavities of ni{\'o}bio via ion 
                         implantation by immersion in plasma of nitrogen for the 
                         gravitational waves detector Mario Schenberg",
             language = "pt",
                pages = "113",
                  ibi = "8JMKD3MGP3W34R/3RJ5JR2",
                  url = "http://urlib.net/rep/8JMKD3MGP3W34R/3RJ5JR2",
           targetfile = "publicacao.pdf",
        urlaccessdate = "30 nov. 2020"
}


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