Pour voir les autres types de publications sur ce sujet consultez le lien suivant : Bi/Cu.
Thèses sur le sujet « Bi/Cu »
Créez une référence correcte selon les styles APA, MLA, Chicago, Harvard et plusieurs autres
Consultez les 50 meilleures thèses pour votre recherche sur le sujet « Bi/Cu ».
À côté de chaque source dans la liste de références il y a un bouton « Ajouter à la bibliographie ». Cliquez sur ce bouton, et nous générerons automatiquement la référence bibliographique pour la source choisie selon votre style de citation préféré : APA, MLA, Harvard, Vancouver, Chicago, etc.
Vous pouvez aussi télécharger le texte intégral de la publication scolaire au format pdf et consulter son résumé en ligne lorsque ces informations sont inclues dans les métadonnées.
Parcourez les thèses sur diverses disciplines et organisez correctement votre bibliographie.
1
Nomssi, Nzali Jacques Hubert Christian. « Nahordnung und mittelreichweitige Ordnung in den binären Legierungsschmelzen : Ag-Bi, Bi-Cu, Cu-Pb, Ga-Tl ». Doctoral thesis, Universitätsbibliothek Chemnitz, 2000. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-200000845.
Texte intégralRésumé :
Die Arbeit befaßt sich mit binären Legierungssystemen, die eine geringe Mischbarkeit der Komponenten im festen Zustand und eine Entmischungstendenz in der Schmelze aufweisen. Die Nahordnung in den binären Legierungsschmelzen Ag-Bi, Bi-Cu und Cu-Pb wird über einen großen Konzentrationsbereich mit Röntgenbeugung untersucht, die Nahordnung und die mittelreichweitige Ordnung in der Ga-Tl-Schmelze hingegen im kritischen Bereich mit Neutronenweitwinkel- und Kleinwinkelbeugung. Ag-Bi und Bi-Cu sind eutektische Systeme mit einem Wendepunkt in der Liquiduslinie, während die Systeme Cu-Pb und Ga-Tl monotektisch sind und eine Mischungslücke im flüssigen Bereich aufweisen. Die Arbeit stellt die verwendeten Beugungsmethoden vor und beschreibt die Röntgendiffraktometrie besonders ausführlich. Die erhaltenen Strukturfaktoren und Paarverteilungsfunktionen werden dargestellt und mit anderen Untersuchungen verglichen. Durch Modellierung werden charakteristische Eigenheiten der Entmischungssysteme wie die Aufspaltung des ersten Maximums, die negativen Faber-Ziman-Strukturfaktoren bei kleinen Q-Werten und die schwache Struktur bei großen Q-Werten qualitativ wiedergegeben. Im Fall der Bi-Cu Schmelze wird durch Kombination von Daten aus Röntgen- und Neutronenbeugung mit Reverse Monte Carlo Simulation ein neuer Satz von partiellen Strukturfaktoren ermittelt, bei dem die partiellen Strukturfaktoren S_{BiCu}(Q) für die Bi-Cu-Wechselwirkung über den gesamten Konzentrationsbereich zuverlässiger sind als zuvor. Mit der Kleinwinkelstreuung werden die Konzentrationsfluktuationen im kristischen Bereich der Ga-Tl-Legierungsschmelze quantitativ beschrieben(Short- and medium-range order in the binary liquid alloys : Ag-Bi, Bi-Cu, Cu-Pb, Ga-Tl) The short-range order (SRO) and the medium-range order (MRO) are investigated in binary alloys with a negligible solubility of the components in the solid state and a demixing tendency in the liquid state. Ag-Bi and Bi-Cu are eutectic systems with an inflexion point in the liquidus line; Cu-Pb and Ga-Tl are monotectic with a miscibility gap in the liquid state. The SRO in the Ag-Bi, Bi-Cu and Cu-Pb melts is studied by means of X-ray diffraction over a large concentration range, whereas wide-angle and small-angle neutron scattering are used for investigation of the SRO and MRO of the Ga-Tl melt near the critical concentration. The diffraction methods used in the work are presented. The treatment of the X-ray scattering data is discussed in detail. The obtained Faber-Ziman total structure factors S(Q) and pair correlation functions g(r) are plotted and compared with results from the literature. The peculiarities of S(Q) such as the splitting of the first maximum, the negative Faber-Ziman structure factors in the Q-range near 1 Å^-1, the vanishing structure oscillations for Q-values beyond the first maximum are described qualitatively with a simple demixing model. In the case of the Bi-Cu melt, the contrast between X-Ray and neutron diffraction is used to assess the partial structure factors with Reverse Monte Carlo simulation. It is shown that the MRO of the Ga-Tl melt at the critical concentration is well described with a correlation length in the Ornstein-Zernike theory
2
Eddike, Driss. « Contribution à l'étude des systèmes Ag-Cu-Tl-Te et Cu-Bi-Se caractérisation thermoélectriques des matériaux / ». Grenoble 2 : ANRT, 1987. http://catalogue.bnf.fr/ark:/12148/cb37604801w.
Texte intégral
3
Ковалюк, З. Д., І. В. Мінтянський et П. І. Савицький. « Спектри електрохімічного імпедансу системи Li/Cu[4]Bi[6]S[11] ». Thesis, Сумський державний університет, 2015. http://essuir.sumdu.edu.ua/handle/123456789/40974.
Texte intégralRésumé :
У роботі представлені результати досліджень гальванічної пари Li/Cu4Bi6S11, а також електронних та іонних властивостей системи методом імпедансної спектроскопії. Досліди виконані для елементів
типорозміру „2325”.
4
Silva, Bismarck Luiz. « Correlações entre parâmetros microestruturais, parâmetros térmicos e resistência mecânica de ligas Sn- Bi e Sn-Bi-(Cu,Ag) ». Universidade Federal de São Carlos, 2016. https://repositorio.ufscar.br/handle/ufscar/8263.
Texte intégralRésumé :
Submitted by Izabel Franco (izabel-franco@ufscar.br) on 2016-10-26T17:47:35Z
No. of bitstreams: 1
TeseBLS.pdf: 15809941 bytes, checksum: e94eb4f0e858901ec9568dacd81ecf51 (MD5)Approved for entry into archive by Marina Freitas (marinapf@ufscar.br) on 2016-11-08T18:28:27Z (GMT) No. of bitstreams: 1 TeseBLS.pdf: 15809941 bytes, checksum: e94eb4f0e858901ec9568dacd81ecf51 (MD5)
Approved for entry into archive by Marina Freitas (marinapf@ufscar.br) on 2016-11-08T18:28:33Z (GMT) No. of bitstreams: 1 TeseBLS.pdf: 15809941 bytes, checksum: e94eb4f0e858901ec9568dacd81ecf51 (MD5)
Made available in DSpace on 2016-11-08T18:28:40Z (GMT). No. of bitstreams: 1 TeseBLS.pdf: 15809941 bytes, checksum: e94eb4f0e858901ec9568dacd81ecf51 (MD5) Previous issue date: 2016-10-07
Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
The present research aims to develop a theoretical/experimental analysis of the combined effects of solidification thermal parameters, Bi content and addition of ternary elements (Cu, Ag) on the final microstructure aspects and on the final mechanical resistances of directionally solidified Sn-Bi, Sn-Bi-Ag and Sn-Bi-Cu solder alloys under transient heat flow conditions. Hence, experimental interrelations between microstructure and thermal parameters and between mechanical properties and microstructure could be established. The microstructures regarding the Sn-34wt.%Bi and Sn-52wt.%Bi alloys show the presence of β-Sn dendrites with Bi precipitates on their own, being enveloped by a lamellar binary Sn-Bi eutectic. The Sn-58wt.%Bi eutectic alloy show a variety of microstructures along the length of the directionally solidified casting, which includes binary eutectic, Bi plates, Bi trifoils and fishbone eutectic. In the case of the ternary Sn-Bi-Ag and Sn-Bi-Cu chemistries, microstructures are constituted by β-Sn dendrites decorated with Bi particles, Bi-Sn eutectic and Cu6Sn5 and Ag3Sn intermetallic particles for the Cu and the Ag bearing alloys, respectively. Experimental growth laws have been derived for both dendritic (λ1, λ2, λ3) and eutectic (λfine, λcoarse) arrangements considering the following alloys: binary Sn-34wt.%Bi, Sn-52wt.%Bi e Sn-58wt.%Bi alloys and ternary Sn- 34wt.%Bi-0.1wt.%Cu, Sn-34wt.%Bi-0.7wt.%Cu e Sn-33wt.%Bi-2wt.%Ag. Considering the binary Sn-Bi, it has been observed that increasing Bi content (34wt.%-->52wt.%-->58wt.%Bi), may cause a decrease on both strength and ductility, except for the sample at P=6mm of the Sn-52wt%Bi alloy. Hall-Petch type functional correlations have been able to represent the evolution of the tensile mechanical properties for the examined Sn-Bi and Sn-Bi-X alloys.
A presente proposta objetiva desenvolver uma análise teórico/experimental sobre os efeitos combinados dos parâmetros térmicos de solidificação (velocidade de solidificação VL e taxa de resfriamento, ṪL), do teor de Bi e das adições de terceiros elementos (Cu, Ag) na microestrutura e na resistência mecânica de ligas Sn-Bi, Sn-Bi-Ag e Sn-Bi-Cu solidificadas unidirecionalmente, estabelecendo correlações experimentais do tipo microestrutura/parâmetros térmicos e microestrutura/propriedades mecânicas. As microestruturas para as ligas binárias Sn-34%Bi e Sn-52%Bi são constituídas de dendritas de Sn com precipitados de Bi em seu interior, circundadas por um eutético lamelar binário, Sn-Bi. A liga eutética Sn-58%Bi mostrou uma ampla gama de microestruturas ao longo de todo o lingote, englobando o eutético binário Sn-Bi, placas e trifoils de Bi e eutético fishbone. Quanto às ligas ternárias Sn-Bi-Cu e Sn-Bi-Ag observa-se que as microestruturas são constituídas de dendritas β-Sn “decoradas” com partículas de Bi em seu interior, circundadas por uma mistura eutética irregular (Bi+Sn) e seus respectivos compostos intermetálicos primários Cu6Sn5 e Ag3Sn, respectivamente. As leis de crescimento experimentais dendrítico (λ1, λ2, λ3) e eutético (λfino, λgrosseiro) para as ligas binárias Sn-34%Bi, Sn-52%Bi e Sn-58%Bi e para as ligas ternárias Sn-34%Bi- 0,1%Cu, Sn-34%Bi-0,7%Cu e Sn-33%Bi-2%Ag em função de V e Ṫ foram caracterizadas por equações na forma de potência com aplicação de expoentes típicos. No caso das ligas binárias Sn-Bi, foi observado que com o aumento do teor de Bi (34%-->52%-->58%Bi), tanto o limite de resistência à tração (σt) quanto o alongamento específico diminuem, com exceção dos resultados para a amostra P=6mm da liga Sn-52%Bi. Relações funcionais do tipo Hall-Petch foram capazes de descrever a variação das propriedades mecânicas de tração de ligas Sn-Bi e Sn-Bi-X.
5
PAN, GUOQIANG. « Etude structurale des materiaux supraconducteurs de la famille bi-sr-cu-o ». Paris 11, 1992. http://www.theses.fr/1992PA112407.
Texte intégralRésumé :
Cette these presente l'etude structurale, par diffusion des rayons x, du materiau supraconducteur bi#2sr#2cuo#6+, ainsi que des composes substitues au plomb sur le site du bismuth, et au lanthane (ou praseodyme) sur le site du strontium, a pression normale et a temperature ambiante. Dans sa premiere partie, elle decrit et analyse les phases modulees incommensurables presentes dans ces materiaux en fonction des differentes substitutions, notamment le sens de variation de la composante selon -b#*- du ou des vecteurs de modulation: pour les composes (bi#2#-#xpb#x)sr#2cuo#6#-#, la composante q#b decroit avec -x-; pour les composes bi#2(sr#2#-#xm#x)cuo#6#+# (m=la, pr), ou pour ceux d'exces de bismuth, la composante q#b croit avec -x-. Dans sa deuxieme partie, cette these presente une analyse de symetrie des modes normaux de vibration. En comparant les resultats experimentaux aux calculs, les valeurs de l'amplitude de deplacement pour les atomes lourds (bi, sr) dans les composes (bi#2#-#xpb#x)sr#2cuo#6#-# (x=0,1) et bi#2(sr#2#-#xbi#x)cuo#6#+# (x=0,4) ont ete estimes. Dans sa derniere partie, cette these discute la liaison entre le taux de transfert de charges, entre les plans cu-o#2 et bi-o, et la periode de modulation de distorsion du reseau correspondante et propose qu'une onde de densite de charge puisse etre l'origine possible de la modulation dans ces materiaux dont le vecteur d'onde est lie a un vecteur d'onde de fermi par la relation q#b=4k#f
6
McLean, Mark J. « Small-scale fracture toughness studies of grain boundary embrittlement in Cu-Bi alloys ». Thesis, Lehigh University, 2013. http://pqdtopen.proquest.com/#viewpdf?dispub=3589920.
Texte intégralRésumé :
Grain boundary embrittlement in the Cu-Bi alloy system was investigated using small-scale fracture toughness tests that were based on commonly used bulk-scale tests. Tests were conducted on pure and Bi-doped <001> twist Cu bicrystals with misorientation angles of 6, 13, and 33° in order to determine the effect of misorientation angle on the degree of embrittlement. The results of these tests showed that the 6° grain boundary was nearly immune to embrittlement, showing little to no differences in fracture toughness values and failure mechanisms between the pure and doped specimens. However, the 33° boundary exhibited a significant amount of embrittlement, with a nearly 40% decrease in fracture toughness in the doped specimens compared to the pure and a distinct shift in the failure mechanism from transgranular shear to intergranular fracture. The 13° boundary exhibited an intermediate amount of embrittlement with a measurable drop in toughness, but not a clear shift in the failure mechanism. These results are consistent with previously published results from tests on bulk-scale bicrystals.
Furthermore, a single-crystal plasticity model was incorporated into a commercial finite element software package (ABAQUS) in order to investigate the development of the plastic zone in front of the notches created in the test specimen. It was found that the size of this zone was likely constrained by the specimen dimensions, which had a significant impact on the measured fracture toughness values.
7
Potter, Charles D. « Search for evidence of fermi surface nesting in Bi₂Sr₂Ca₁Cu₂O₈ ». Diss., Virginia Tech, 1992. http://hdl.handle.net/10919/40088.
Texte intégral
8
Ковалюк, З. Д., І. В. Мінтянський et П. І. Савицький. « Розрядні параметри та імпеданс джерел струму Li/Cu[4]Bi[5]S[10] ». Thesis, Сумський державний університет, 2013. http://essuir.sumdu.edu.ua/handle/123456789/44111.
Texte intégralRésumé :
Хоча літієві джерела струму мають високу ємність у порівнянні із традиційними електрохімічними системами, їх значним недоліком є низькі допустимі струмові навантаження, тому пошук нових високопровідних катодних матеріалів залишається актуальним. Відомо, що перспективними в цьому плані є багатокомпонентні сполуки на основі халькогенідів вісмуту, наприклад CuBiSe[2] та CuBiSeS.
9
Fischer, David S. Ph D. Massachusetts Institute of Technology. « Novel approaches to low temperature transient liquid phase bonding in the In-Sn/Cu and In-Sn-Bi/Cu systems ». Thesis, Massachusetts Institute of Technology, 2008. http://hdl.handle.net/1721.1/44424.
Texte intégralRésumé :
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2008.Vita.
Includes bibliographical references (leaves 112-113).
A fluxless low temperature transient liquid phase (LTTLP) bonding process was studied as a method of producing Cu/Cu joints below 125°C and 75°C using interlayer alloys from the In-Sn and In-Sn-Bi systems. Using thermodynamic models, three different compositions (wt. %) of base alloys were chosen to accomplish this task: 50In-43.6Sn-6.4Bi (Tm = 110°C) and eutectic 50.9In-49.1Sn (Tm = 120°C) alloys were used for bonding at 125°C and a eutectic 48.3In-15.6Sn-36.1Bi (Tm = 60°C) alloy was used for bonding at 75°C. In addition, novel approaches to TLP bonding, including the addition of base material to the interlayer alloy and application of an electroless Ni diffusion barrier layer, were employed in an attempt to optimize this joining method. The LTTLP processes were assessed based on their abilities to produce joints with minimal thickness, high reflow temperatures, and good mechanical properties at room/elevated temperatures. It was found that interlayer alloys containing higher Bi contents produced the thinnest joints, with the 48.3In-15.6Sn-36.1Bi alloy producing joints on the order of 10 gm. Increases in nominal Cu composition of the interlayer alloy tended to form larger joints. Application of the Ni layer was observed to decrease the growth rate of the eutectic In-Sn joints made with 5 wt % Cu additions. Shear tests were performed on the joints at room (25°C) and operating (service) temperatures (100°C). Most of the TLP joints had room temperature shear strengths around 13,000 - 17,000 psi (= 90 - 120 MPa), although increases in strength were observed for eutectic In-Sn joints with 2.5 and 5 wt% Cu additions. At operating temperature, TLP joints made within the In-Sn-Cu system were found to have strengths an order of magnitude higher than those made in the In-Sn-Bi-Cu system.
(cont.) Poor mechanical response of the Bicontaining joints was due to the presence of low melting In-Bi IPs present in the reaction zone. Eutectic In-Sn TLP joints made with 2.5 and 5 wt% Cu additions were found to have operational temperature shear strengths of 6,000 - 7,500 psi ( 40 - 50 MPa) and 7,500 - 9,500 psi (= 50 65 MPa), respectively.
by David S. Fischer.
S.M.
10
Caillard, Renaud. « Synthèse, propriétés supraconductrices et thermomécaniques de céramiques texturées des systèmes Y-Ba-Cu-O et Bi-Pb-Sr-Ca-Cu-O ». Caen, 2002. http://www.theses.fr/2002CAEN2016.
Texte intégralRésumé :
Au cours de leur cycle d'utilisation, les céramiques supraconductrices sont soumises à des contraintes mécaniques et / ou thermiques qui peuvent entraîner une dégradation rédhibitoire des performànces électriques, voire la destruction des dispositifs. Dans ce travail, nous avons élaboré puis évalué les caractéristiques thermomécaniques de céramiques texturées des systèmes Y-Ba-Cu-O et Bi-Pb-Sr-Ca-Cu-O. Pour assurer une stoechiométrie et une homogénéité constantes et maîtrisées des matières de départ, nous avons synthétisé les poudres précurseurs par voie sol-gel pour Bi2223 et par voie solide pour Y123. Les conditions optimales de formation (température et durée de frittage sous air) de la phase Bi2223 ont été déterminéess et les produits finaux caractérisés par diffraction RX, granulométrie et par des observations au MEB. L'influence des paramètres majeurs de frittage-forgeage (cycles thermiques et de pressage, durée de maintien sous charge) a été étudié et un cycle optimisé sous air a ainsi été défini par une température de 845° C et une contrainte de 23,6 MPa appliquée pendant 20 heures. La texturation du système Y-Ba-Cu-O a été effectuée par la méthode de Top Seeding Melt Texture growth (TSMTG) [etc]
11
Jain, Akshay Ashok. « Design and LENS® Fabrication of Bi-metallic Cu-H13 Tooling for Die Casting ». The Ohio State University, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=osu1385987045.
Texte intégral
12
Teruzzi, Tiziano. « Investigation of the vortex dynamics in the high-temperature superconductors Bi₂Sr₂CaCu₂O₈, YBa₂Cu₃O₇₋{delta} and YBa₂Cu₄O₈ / ». Zürich, 1993. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=10361.
Texte intégral
13
TROUILLEUX, LIONEL. « Elaboration et etude des proprietes electriques et magnetiques de ceramiques supraconductrices texturees dans les systemes la-sr-cu-o, nd-ce-cu-o et bi-sr-ca-cu-o ». Paris 11, 1991. http://www.theses.fr/1991PA112031.
Texte intégralRésumé :
Des ceramiques supraconductrices texturees ont ete elaborees par solidification dirigee, dans les systemes la-sr-cu-o, nd-ce-cu-o et bi-sr-ca-cu-o. L'existence d'une transformation eutectique entre la#2##xsr#xcuo#4 (ou nd#2##xce#xcuo#4) et cuo, nous a permis d'obtenir des materiaux biphases a microstructures orientees. Dans le systeme bi-sr-ca-cu-o, des materiaux textures quasiment monophases, constitues de plaquettes supraconductrices orientees parallelement a l'axe de croissance ont ete elabores a partir de compositions voisines de la stchiometrie du compose bi#2sr#2cacu#2o#8. L'etude par diffraction x revele une direction de croissance preferentielle 110 pour la phase supraconductrice dans les trois systemes. Les densites de courant critique jc, evaluees a partir de cycles d'aimantation en utilisant le modele de bean, sont respectivement de 3 10#5, 10#3 et 10#6 a?cm##2 a 4 k pour les composes la#2##xsr#xcuo#4 (x0,14), nd#2##xce#xcuo#4 (x0,17) et bi#2sr#2cacu#2o#8. Une anisotropie jc#a#b/jc#c30 a ete determinee pour les composes la#2##xsr#xcuo#4 et bi#2sr#2cacu#2o#8. Les temperatures de milieu de transition supraconductrice, determinees par des mesures de resistivite, sont respectivement 36 k, 21 k et 92 k pour ces trois composes. Les densites de courant critique jc, determinees par transport selon l'axe de solidification sont de 800 a?cm##2 a 18 k pour la#2##xsr#xcuo#4 et de 3000 a?cm##2 a 77 k pour bi#2sr#2cacu#2o#8. Ces valeurs sont tres superieures a celles obtenues dans des materiaux polycristallins isotropes. Ceci resulte de l'orientation des joints de grains et des plans de conduction (cu-o) de la phase supraconductrice selon l'axe de solidification
14
Ganapathy, Subramanian Santhana. « Bi-Sr-Ca-Cu-O thin films grown by flash evaporation and pulsed laser deposition ». Texas A&M University, 2003. http://hdl.handle.net/1969.1/47.
Texte intégralRésumé :
Bismuth-Strontium-Calcium-Copper-Oxide (BSCCO) compounds are an important family of compounds that have one of the highest transition temperatures among all high-temperature superconductors. The compound is known to exist in three distinct phases, commonly referred to as the 2201, 2212 and 2223 phases. Of these three phases, the 2212 and 2223 phases are the most important, as their transition temperature is higher than the boiling point of liquid nitrogen. It is desirable to produce the compound in thin film form, as the bulk samples are normally polycrystalline.
This thesis compares thin films produced by two techniques for depositing BSCCO in order to understand the effect of various processing parameters on the final quality of the thin films. Thin films were grown by flash evaporation at Texas A&M University, and by pulsed laser deposition (PLD) at the University of Wollongong, Australia. The latter of these techniques is widely used for growing thin films of various compounds. Single-phase 2212 films were grown on a MgO substrate using the pulsed laser deposition technique from commercially available 2212 powder. The effect of annealing on the thin films was also studied.
15
Filgueiras, Bernardo de Carvalho. « Depósito vulcanogênico polimetálico (Zn, Pb, Cu ± (Ag-Bi)) Artulândia, Arco Magmático Paleoproterozóico Campinorte, Brasil Central ». reponame:Repositório Institucional da UnB, 2015. http://dx.doi.org/10.26512/2015.05.D.18711.
Texte intégralRésumé :
Dissertação (mestrado)—Universidade de Brasília, Instituto de Geociências, Programa de Pós-Graduação, 2015.Submitted by Raquel Viana (raquelviana@bce.unb.br) on 2015-10-20T18:19:11Z No. of bitstreams: 1 2015_BernardodeCarvalhoFilgueiras.pdf: 10205948 bytes, checksum: 5831ce95b5868213c1b82d073a3c7a65 (MD5)
Approved for entry into archive by Marília Freitas(marilia@bce.unb.br) on 2015-11-11T11:19:04Z (GMT) No. of bitstreams: 1 2015_BernardodeCarvalhoFilgueiras.pdf: 10205948 bytes, checksum: 5831ce95b5868213c1b82d073a3c7a65 (MD5)
Made available in DSpace on 2015-11-11T11:19:05Z (GMT). No. of bitstreams: 1 2015_BernardodeCarvalhoFilgueiras.pdf: 10205948 bytes, checksum: 5831ce95b5868213c1b82d073a3c7a65 (MD5)
O depósito polimetálico recém descoberto na região de Artulândia – GO está hospedado na sequência Metavulcanossedimentar de Artulândia. À sequência estão associadas rochas intrusivas, aflorando na Zona Interna da Faixa Brasília, entre o Complexo de Barro Alto e a Sintaxe dos Pirineus. Até então, estas rochas tinham contexto geológico pouco definido. Dessa forma, o objetivo desse estudo é a caracterização genética da mineralização, além da caracterização geológica, geoquímica e geocronológica da Sequência Metavulcanossedimentar de Artulândia. A Sequência de Artulândia consiste de rochas supracrustais, compostas por rochas metavulcânicas félsicas e básicas, em menor proporção, e rochas metassedimentares clásticas e químicas, que ocorrem como lentes. Associados a estas rochas ocorrem corpos de composição tonalítica a granodiorítica. Análises químicas de rocha total realizadas em rochas metavulcânicas bimodais indicam magma peraluminoso, de assinatura tectônica em contexto intra-placa. As rochas intrusivas apresentam assinatura calci-alcalina de médio potássio, caráter meta a peraluminoso e assinatura tectônica de magmas originados em arcos magmáticos similares a adakitos. Idade U-Pb em zircão para Sequência é de 2.142 Ma, enquanto para as rochas intrusivas houve variação de idades entre 2.130 e 2.156 Ma. Idades modelo (TDM), com base no método Sm-Nd, relativos a sequência e rochas plutônicas variam de 2.6 a 2.14 Ga, com valores de εNd positivos, o que indica o caráter juvenil dessas rochas. Os dados apresentados demostram que o Domínio Artulândia foi formado em contexto tectônico de arco magmático Paleoproterozóico similar ao Arco Magmático Campinorte. O depósito polimetálico Zn-Pb-Cu (Ag-Bi) de Artulândia é de origem vulcanogênica não usual em ambiente de back-arc continental Paleoproterozóico. Está hospedado em sequência metavulcânica bimodal dominada por rochas félsicas. São observadas alterações hidrotermais metamorfisadas em facies anfibolito próximas às zonas mineralizadas representadas por tremolita, espessartita, clinocloro, carbonato, talco e alterações distais representadas por biotita, sericita, carbonato, espessartita, turmalina e epidoto acompanhadas de sulfetos disseminados. A zona mineralizada é composta por lentes de sulfetos maciços a semi-maciços de esfalerita, pirita, galena, calcopirita, e, em menor proporção, bismuto nativo, prata nativa, molibdenita, magnetita e hematita. Análises químicas das rochas alteradas mostram enriquecimento hidrotermal em MgO, MnO, CaO, FeO e C, e perda em SiO2 e K2O. A química mineral mostra altas concentrações de bismuto em galena, pirita e calcopirita e variações de teores de ferro na esfalerita que quando disseminada em alterações distais são mais ricas em ferro do que na esfalerita maciça da zona mineralizada. Também são observadas anomalias de prata na zona mineralizada e ausência de anomalias de ouro. Análises químicas de isótopos de enxofre indicam baixa variação e constância em valores positivos próximos a dez. Valores desta ordem indicam contribuição de mistura de fluidos marinhos e magmáticos para a formação de enxofre contido no sulfeto. O conteúdo metálico da mineralização indica que o depósito é classificado em vulcanogênico não-aurífero formado em ambiente de arco magmático ou back-arc. A mineralização de Artulândia é classificada como vulcanogênica formada em back-arc continental Paleoproterozóico. Este contexto é observado em outras partes mundo e tem importantes depósitos econômicos. O depósito Artulândia tem caráter inédito na Faixa Brasília, abrindo novos horizontes prospectivos nesta região.
The polymetallic mineralization recently discovered in Artulândia region - GO, is hosted in Artulândia metavolcano-sedimentary sequence and associated intrusive rocks. These units belong to the Internal Zone of the Brasília Belt, they are located between the Barro Alto Complex and the Pirineus Syntaxy, until then these rocks had uncertain geological context. Thus, the aim of this study is the genetic characterization of the mineralization, in addition, the geological characterization, geochemical and geochronological of Artulândia Sequence. The Artulândia Sequence consists of supracrustal rocks, composed of felsic metavolcanic rocks and basic, to a lesser extent, and clastic metasedimentary rocks and chemical occurring as lenses. Associated with these rocks are observed intrusive bodies of tonalitic to granodioritic rocks. Whole rock chemical analyzes performed in metavolcanic rocks indicate bimodal volcanism, predominantly calc-alkaline, peraluminous, tectonics signature indicates magma origin in intra-plate regions. Intrusive rocks have medium potassium calc-alkaline signature, meta-peraluminous magmatic character and tectonic signature derived from magmatic arcs similar to adakites. U-Pb zircon age for sequence is 2.142 Ga, as to the intrusive rocks varying between 2.130 and 2.156 Ga. Sm-Nd model ages (TDM) for the sequence and intrusive rocks ranging from 2.6 to 2.14 Ga, with positive εNd values, which indicates the juvenile characteristics of rocks. The data presented demonstrate that the Artulândia Domain was formed in a tectonic context of Paleoproterozoic magmatic arc similar to Campinorte Magmatic Arc. The polymetallic Zn-Pb-Cu (Ag-Bi) mineralization of Artulândia is unusual volcanogenic mineralization origin in paleoproterozoic back-arc environment. The mineralization is hosted on bimodal metavolcanic sequence dominated by felsic rocks. Metamorphosed hydrothermal asemblies are observed in amphibolite facies proximal to the mineralized zones and are represented by tremolite, spessartine, clinochlore, carbonate, talc and distal hydrothermal alterations represented by biotite, sericite, carbonate, spessartine, tourmaline and epidote accompanied by disseminated sulfides. The mineralized zone consists of massive sulphide lenses of semi-massive sphalerite, pyrite, galena, chalcopyrite, and to a lesser extent, native bismuth, native silver, molybdenite, magnetite and hematite. Chemical analyzes of altered rocks show hydrothermal enrichment in MgO, MnO, CaO, FeO and C, and loss in SiO2 and K2O. Mineral chemical analyzes show high concentrations of bismuth in galena, pyrite and chalcopyrite. Variations in the iron content sphalerite are also observed, disseminated sphalerite in distal alteration are richer in iron than sphalerite groundmass of the mineralized zone. Silver anomalies and absence of gold anomalies are also observed in all zones of mineralization. Chemical analysis of sulfur isotopes indicate low variation and constancy in positive values coming through ten. Values of this order indicate contribution of mixing fluids and marine magmatic for the formation of sulfur contained in the sulphide. The metal content of the mineralization indicates that the deposit is classified as non-auriferous volcanogenic mineralization formed in magmatic arc environment or back-arc. Based in data described before, the Artulândia mineralization is classified as volcanogenic formed in paleoproterozoic continental back-arc. This context is observed in many places in the world and has important economic deposits. The Artulândia mineralization has unprecedented nature in Brasília Belt, opening new horizons prospective in this region.
16
Denis, Céline. « Synthèse d'agents chélateurs bi-fonctionnels pour le marquage de peptides avec le [indice supérieur 64]Cu ». Mémoire, Université de Sherbrooke, 2015. http://hdl.handle.net/11143/6756.
Texte intégralRésumé :
Résumé : Grâce à des caractéristiques physiques particulières, le [indice supérieur 64]Cu (T[indice inférieur 1/2]= 12.7 h; β[indice supérieur+], 0.65 MeV [17.8 %]; β[indice supérieur −], 0.58 MeV [38.4 %]) est un candidat idéal pour l’imagerie TEP et la radiothérapie ciblée du cancer. Son utilisation est actuellement limitée par la disponibilité de chélateurs bi-fonctionnels (CBFs) offrant une résistance élevée aux réactions de transmétallation in vivo. Récemment nous avons développés deux nouveaux CBFs cycliques, DOTHA[indice inférieur 2] et NOTHA[indice inférieur 2], portant des ligands hydroxamates pour la complexation au [indice supérieur 64]Cu. Ces CBFs possèdent une cinétique de marquage rapide dans des conditions très douces, une stabilité élevée in vivo et un profil de biodistribution favorable avec une clairance rapide. Nous proposons maintenant d’étendre notre approche à la préparation de CBFs acycliques plus flexibles et compacts afin de moduler les propriétés biologiques et la pharmacocinétique des traceurs peptidiques. Le but de mon projet de maîtrise est de développer une série de chélateurs acycliques dérivés de l'histidine et de l'acide glutamique et fonctionalisés avec des groupements hydroxamates pour identifier un CBF offrant un complexe stable in vivo avec le [indice supérieur 64]Cu(II). Les CBFs ont été préparés en solution pour faciliter l’optimisation de chaque étape réactionnelle. Les groupements chélatants hydroxamates ont été sélectionnés pour leur habilité à former des complexes stables avec différents métaux et ils ont été liés en position N-terminale et sur la chaîne latérale des acides aminés grâce à des réactions de substitution nucléophile. Les groupements para-methoxy-benzyles ont été judicieusement sélectionnés pour la protection des groupements hydroxamates afin de faciliter, au besoin, une déprotection sélective sous des conditions très douces. L’optimisation du marquage a été effectuée avec l’isotope stable du cuivre et ensuite avec le [indice supérieur 64]Cu en faisant varier le contre ion métallique, le pH, la concentration, et la température. Le CBF offrant la plus grande stabilité, soit celui dérivé de l’histidine, a été conjugué à un peptide, le H[indice inférieur 2]N-PEG-[D-Tyr[indice supérieur 6],βAla[indice supérieur 11],Thi[indice supérieur 13],Nle[indice supérieur 14]]bombesin(6-14) (BBN), se liant fortement aux récepteurs de la relâche de la gastrine surexprimés dans les cancers du sein et de la prostate. La stabilité et l’activité spécifique du CBF-histidine et du radiotraceur marqués au [indice supérieur 64]Cu s’est avérée faible in vitro. Il est connu que l’activité antibactérienne de ligands hydroxamates est associée à leur capacité à complexer le fer. En perspective, comme nos chélateurs complexent très fortement le Fe(III), une alternative pour ces composés serait d’évaluer leur capacité à inhiber la croissance et la prolifération des bactéries. || Abstract : Thanks to its particular physical characteristics, [superscript 64]Cu (T[subscript ½= 12.7 h; β[superscript +], 0.65MeV [17.8 %]; β[superscript −], 0.58MeV [38.4 %]) is an ideal candidate for PET imaging and targeted cancer radiotherapy. Currently, its use is limited by the availability of bi-functional chelators (BFCs) which give high resistance to in vivo transmetallation reactions. Recently, we developed two new cyclic BFCs, DOTHA[subscript 2] and NOTHA[subscript 2], bearing hydroxamate pendant arms for the complexation with [superscript 64]Cu. Those BFCs have fast labeling kinetics under very mild conditions, a high in vivo stability and a biodistribution profile which is favorable with a fast clearance. Now, we propose to expand our approach to the preparation of acyclic BFCs, which are more flexible and compact, in order to better modulate biological properties and the pharmacokinetics of the peptidic tracers. The goal of my Master’s degree project is to develop a series of acyclic chelators derived from histidine and glutamic acid and functionalized with hydroxamate pendant arms to identify a BFC that shows highly stable in vivo complexes with [superscript 64]Cu(II). BFCs have been prepared in solution to facilitate the optimization of each reactive step. Hydroxamate chelating groups have been selected for their ability to form stable complexes with different metals and they have been conjugated in N-terminal position and on the lateral chain of amino acids via nucleophilic substitution reactions. Para-methoxy-benzyl groups have been judiciously selected for the protection of the hydroxamate groups to facilitate, if needed, a selective deprotection under mild conditions. The labeling optimization has been performed with a stable copper isotope, and then with [superscript 64]Cu varying the metallic counter-ion, pH, concentration and temperature. The BFC having the highest stability, the one derived from histidine, was conjugated to a peptide, H[subscript 2]N-PEG-[D-Tyr[superscript 6],βAla[superscript 11],Thi[superscript 13],Nle[superscript 14]]bombesin(6-14) (BBN), strongly bounding the gastrin releasing peptide receptor, which is overexpressed in breast and prostate cancers. Both the stability and specific activity of BFC-histidine of the radiotracer labeled with [superscript 64]Cu were low in vitro. It is known that the antibacterial activity of hydroxamate ligands is associated with their ability to complex iron. In perspective, because our hydroxamate ligands strongly complex Fe(III), an alternative for these compounds would be to assess their ability to inhibit the growth and proliferation of bacteria.
17
Betsi, Thierry Bineli. « PETROGENESIS OF AU-BI-AS-CU, CU-MO ±W, AND BASE-METAL-AU-AG MINERAL OCCURRENCES, IN THE MOUNTAIN FREEGOLD REGION (DAWSON RANGE), YUKON, CANADA ». Thesis, Fredericton : University of New Brunswick, 2012. http://hdl.handle.net/1882/44591.
Texte intégral
18
Boita, Jocenir. « Estudos por espectroscopia de absorção de raios x in situ da formação e reatividade de nanopartículas mono - e bi - metálicas : Pt, Cu e Pt-Cu ». reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2014. http://hdl.handle.net/10183/104575.
Texte intégralRésumé :
Esta tese trata do estudo da formação e da reatividade de nanopartículas (NPs) mono- e bi-metálicas por Espectroscopia de Absorção de Raios X Dispersivo (DXAS) in situ. Uma parte do trabalho foi dedicada a aperfeiçoar o método de preparação das NPs, e ao desenvolvimento de uma instrumentação específica para monitorar a formação das NPs (coloides) da síntese químicas em fase líquida. Com isso, foi possível investigar a formação de NPs de platina (Pt), cobre (Cu) e platina-cobre (Pt-Cu). As NPs obtidas também foram caracterizadas por XRD (X-ray Diffraction), TEM (Transmission Electron Microscopy) e HRTEM (High Resolution Transmission Electron Microscopy). Uma vez formadas e caracterizadas, as NPs foram extraídas da solução coloidal e submetidas a processos térmicos sob atmosferas gasosas (H2S ou H2), ao mesmo tempo que eram analisadas por DXAS in situ. A partir da análise dos dados obtidos foi possível comparar a reatividade das NPs ao envenenamento por enxofre, analisar a sua reversibilidade, além de determinar as energias de ativação (EA) dos processos de sulfetação e redução. O processo de sulfetação das NPs de Pt-Cu se mostrou mais lento do que nas NPs de Pt0,3Pd0,7 e nos casos monometálicos de Pt e Cu, demonstrando que as NPs de Pt-Cu possuem uma maior resistência ao envenenamento por enxofre. Além disso, elas apresentaram reversibilidade ao estado metálico, tornando-as isentas de enxofre após o processo de redução. Tais características torna as NPs de Pt-Cu um material atraente para uso em catálise do Petróleo.This thesis deals with the study of the formation and reactivity of mono-and bi-metallic nanoparticles (NPs) by in situ Dispersive X-ray Absorption Spectroscopy (DXAS). Part of the work was devoted to improve the method of preparation of the NPs, and the development of a specific instrumentation to monitor the formation of NPs (colloids) via chemical synthesis in liquid phase. Thus, it was possible to investigate the formation of NPs platinum (Pt), copper (Cu) and platinum-copper (Pt-Cu). The obtained NPs were also characterized by XRD (X-ray Diffraction), TEM (Transmission Electron Microscopy) and HRTEM (High Resolution Transmission Electron Microscopy). Once formed and characterized, the NPs were extracted from the colloidal solution and submitted to thermal processes under gaseous atmospheres (H2S or H2), while they were analyzed by in situ DXAS. From the data analysis it was possible to compare the NPs reactivity to sulfur poisoning, to analyze its reversibility, and to determine the activation energies (EA) for the reduction and sulfidation processes. The sulfidation of Cu-Pt NPs was slower than for the Pt0.3Pd0.7 NPs and monometallic Pt and Cu cases, showing that the Cu-Pt NPs have a high resistance to sulfur poisoning. Furthermore, they presented reversibility to the metallic state, making them free of sulfur after the reduction process. These features make the Cu-Pt NPs an attractive material for use in oil catalysis.
19
Rubo, Elisabete Aparecida Andrello. « Métodos de processamento e sinterização alternativos para obtenção de pastilhas de (Bi, Pb) - Sr - Ca - Cu - O ». Universidade de São Paulo, 1994. http://www.teses.usp.br/teses/disponiveis/76/76132/tde-13032014-103157/.
Texte intégralRésumé :
Este trabalho trata da obtenção e caracterização de cerâmicas do sistema supercondutor Bi:Pb:Sr:Ca:Cu:O. O pó cerâmico foi feito por dois processos, mistura de óxidos/carbonatos e co-precipitação de oxalatos, com o objetivo de se estabelecer o procedimento mais favorável ao aparecimento da fase de temperatura critica de 110K. A caracterização do pó precursor foi feita através das técnicas de Plasma Indutivamente Acoplado (ICP), Picnometria, Sedigrafia, Difração de Raios X e Microscopia Eletrônica de Varredura. Na etapa de sinterização do pó estudamos, paralelamente a sinterização convencional, uma técnica alternativa de aplicação de corrente elétrica simultaneamente à ação da temperatura com o objetivo de acelerar a reação de formação e promover, possivelmente, uma maior fração da fase de mais alta temperatura critica. Ao final do processamento as amostras foram caracterizadas estruturalmente, por difração de raios X, e quanto às propriedades elétrica (resistividade elétrica) e magnética (susceptibilidade magnética). Na análise comparativa das características elétricas e estruturais das pastilhas obtidas convencional e quimicamente não observamos diferenças significativas entre elas. No entanto as medidas de susceptibilidade magnética mostraram uma grande diversificação de fases com temperaturas criticas abaixo de 110K, para a pastilha obtida por co-precipitação de oxalatos. Também verificamos que a fase 2223 encontra-se, nessa amostra, em maior proporção do que na pastilha proveniente de pó convencional. O processo alternativo de sinterização promoveu algumas alterações no comportamento da resistividade elétrica do materialThis work is about the obtaining and characterizing pellets of the Bi:Pb:Sr:Ca:Cu:O system. The powder was prepared by two processes: oxide/carbonate mixture and oxalate co-precipitation. These two processes were used in order to establish the most favorable process to the 110 K phase formation. The characterization techniques were Inductively Coupled Plasma, Picnometry, Sedigraphy, X Ray Diffraction and SEM. The sinterization was made by conventional and an alternative techniques. The alternative one consists in applying electrical current simultaneously to the temperature action. The expectation was that this technique would accelerate the reactions and consequently, to promote higher volume fraction of the 110K phase. The pellets were structural, electrical and magnetically characterized by X Ray Diffraction, SEM, electrical resistivity and magnetic susceptibility. In the analysis of the electrical and structural characterization of the pellets made by both processing methods, we could not find any difference between them. But, the magnetization measurements indicated that there are numerous phases with critical temperature below 110 K, in addition a higher fraction of 2223 phase, in the pellet made by co-precipitation of oxalates. The alternative sintering process promoted a few alterations in the behavior of the electrical resistivity as a function of the applied temperature
20
Wade, C. Austin. « Investigation of Grain Boundary Segregation and Embrittlement Mechanisms of the Cu-Bi System by Analytical Electron Microscopy ». Thesis, Lehigh University, 2015. http://pqdtopen.proquest.com/#viewpdf?dispub=3723911.
Texte intégralRésumé :
Grain boundary (GB) segregation and embrittlement of copper (Cu) by small amounts of bismuth (Bi) has been investigated on 6°, 13°, and 33° Cu twist bicrystals. The results from micro-mechanical double edge notched testing showed no embrittlement effects in the 6° GB. The 33° GB has been shown to be significantly embrittled by the introduction of Bi. Single edge notch testing of the 13° GB also showed a reduction in fracture toughness. These mechanical results have been interpreted through the use of analytical electron microscopy (AEM) studying the GB geometry, the atomic structure, the electronic structure, and the chemical compositions of the GBs. The 6° and 33° GBs were found to be close to pure twist boundaries but with more accurate twist angles of 4.3° and 38.0°, respectively. The electronic structure of the GBs was not found to be a good indication of the presence of Bi, which was confirmed on the 13° and 33° GBs. The Bi GB coverage was confirmed via quantitative XEDS on the 33° GB to correspond to 0.12 ± 0.03 monolayers of Bi and through 3-dimensional scanning transmission electron microscope (STEM) through focus imaging to be 0.02 – 0.09 monolayers of Bi. The presence of edge dislocations along the 33° GB was confirmed with Bi segregating to edge dislocation cores. The Bi atoms on the dislocation cores embrittle the GB by increasing the energy required to move a dislocation in response to an applied stress resulting in reduced plasticity at the crack tip which promotes GB cleavage.
21
Choi, Siyoung. « Synthesis and Magnetic Properties of ZrO2 or MgO-containing Y-Ba- Cu-O and Bi-Sr-Ca-Cu-O Superconductors prepared by self-propagating chemical decomposition / ». The Ohio State University, 1994. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487859313343754.
Texte intégral
22
Müller, René. « Die heterogenen Gleichgewichte der festen Phasen im System Bi-Sr-Ca-Cu-Oxid bei 830°C an Luft / ». [S.l.] : [s.n.], 1993. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=9969.
Texte intégral
23
MARTINELLI, ANTONIO E. « Efeito da adicao de chumbo na formacao de fases supercondutoras em ceramicas de Bi-Sr-Ca-Cu-O ». reponame:Repositório Institucional do IPEN, 1991. http://repositorio.ipen.br:8080/xmlui/handle/123456789/10260.
Texte intégralRésumé :
Made available in DSpace on 2014-10-09T12:36:38Z (GMT). No. of bitstreams: 0Made available in DSpace on 2014-10-09T13:59:09Z (GMT). No. of bitstreams: 1 04226.pdf: 1346289 bytes, checksum: ae51647be934d5e52ce7e2787d3ee5b5 (MD5)
Dissertacao (Mestrado)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
24
Dumont, Yves. « Supraconductivite et aspects structuraux dans les cuprates mixtes (bi)is2(sr,la)is2(cu)is1(o)is6+delta ». Paris 11, 1996. http://www.theses.fr/1996PA112539.
Texte intégralRésumé :
Sur des monocristaux, de croissance par flux, de bi-2201 substitues au lanthane, sur lesquels une correspondance entre la composition nominale en lanthane yla, et les parametres de la structure moyenne et de la structure displacive incommensurable avaient ete etablie, nous avons cherche une relation entre la temperature de transition supraconductrice, tc et yla. Par micro-analyse par sonde electronique (epma), nous montrons que le lanthane se substitue de facon homogene et continue sur le site du strontium. La composition stoechiometrique des cristaux etudies est biis2. 1sris1. 9ylaisycuis1ois6+delta. Tc n'est pas directement determine par yla. L'oxygene dans toute sa complexite est suspecte. Via le developpement d'une technique de mesure de resistivite in-situ a haute temperature, nous montrons que dans la gamme 470c, 680c, le terme residuel de la resistivite rho(t) en fonction de la temperature est modifie selon la loi de matthiessen. Tc decroit avec l'augmentation de la temperature de recuit. Le probleme de la diffusion d'oxygene et du degre d'ordre/desordre local est pose. Nous developpons une technique de mesure du coefficient seebeck s(t) en fonction de la temperature, car s(300k) a ete revele comme une mesure efficace et universelle du niveau de dopage en trous dans les autres cuprates. Nous montrons que le substitution en lanthane et les traitements thermiques sont equivalents pour la dependance en temperature de s(t), analysee en termes d'entrainement et de bande etroite. Nous tracons un diagramme de phase tc vs. S(300k) pour le systeme bi-2201 avec differents yla et differentes temperatures tr de recuit. Nous pouvons aller du regime surdope (quand yla=0) au regime sousdope (quand yla et tr sont augmentes). La difference avec les autres cuprates est l'existence d'une bifurcation dans le diagramme de phase pour yla=0. 3 qui coincide avec la transition de phase structurale passant de la symetrie monoclinique a celle orthorhombique. Une forte pression hydrostatique modifie a la fois tc et la dynamique de vortex evaluee par le champ critique resistif. Ce cuprate a bas tc, a sa supraconductivite dominee par sa structure complexe.
25
Albuquerque, Daniel dos Santos. « DETERMINAÇÃO DE Cu²⁺ EM BIOCOMBUSTÍVEIS COM USO DE ELETRODO DE FILME DE BISMUTO, APÓS ELIMINAÇÃO DA INTERFERÊNCIA DO Bi³⁺ ». Universidade Federal do Maranhão, 2013. http://tedebc.ufma.br:8080/jspui/handle/tede/970.
Texte intégralRésumé :
Made available in DSpace on 2016-08-19T12:56:44Z (GMT). No. of bitstreams: 1
Dissertacao Daniel.pdf: 1759359 bytes, checksum: 8e118ed0eeb57413abe7a81e44a65d3f (MD5)
Previous issue date: 2013-06-03Despite the advantages of bismuth film electrode for the determination of trace metals and organic compounds, the Cu²⁺ is an element that has problems when measured with this electrode, since its potential is very close to the Bi³⁺, causing overlapping of peaks. This work presents an alternative to eliminate the interference of Bismuth in the determination of copper in using bismuth film electrodes (BiFE), prepared ex situ mode. The ethanol fuel samples without pre-treatment and biodiesel samples previously digested were used in order to evaluate this electroanalytical procedure. The optimization of the parameters was performed using a complete factorial design 2³ with center point. After several voltammetric experiments, optimal conditions for the determination of Cu²⁺ were the following: Edep = -1.3 V; tpre = 120s; Frequency: 60 Hertz. The voltammograms using anodic stripping voltammetry method in the square wave mode and their corresponding standard addition curves indicated that the bismuth film electrode provides a sensitive and useful procedure for the determination of Cu²⁺ in biofuels. Experiments carried out by the successive addition of aliquots of a standard solution of Cu²⁺, yielded a linear response of peak current to the concentration of metal ion. Good detection limits have been obtained for the determination of Cu²⁺ in ethanol fuel, soybean oil and tallow biodiesels respectively (4.9 x 10ˉ⁸ mol Lˉ¹; 5.60 x 10ˉ⁸ mol Lˉ¹, 1.79 x 10ˉ⁸ mol Lˉ¹). The accuracy was assessed through recovery test (recoveries of 85.6% to 97.05%) and the precision was expressed by the coefficient of variation that ranged from 10% to 18%. The method was successfully applied to two different samples of biodiesel and ethanol fuel and analyzed in triplicate.
Apesar das vantagens do Eletrodo de Filme de Bismuto (BiFE), na determinação de metais traços e compostos orgânicos, o Cu²⁺ é um elemento que apresenta problemas quando quantificado com este eletrodo, uma vez que seu potencial é muito próximo ao do Bi³⁺, causando a sobreposição de picos. Este trabalho apresenta uma alternativa para eliminação da interferência do bismuto na determinação de Cu²⁺ em biocombustíveis (etanol e biodiesel), usando um BiFE, preparado no modo ex situ. As amostras de etanol combustível foram usadas sem tratamento prévio, enquanto as amostras de biodiesel foram previamente digeridas. A otimização dos parâmetros foi realizada com o uso do planejamento fatorial completo 2³ com ponto central. Após vários experimentos voltamétricos, as condições ideais para a determinação de Cu²⁺ foram: Edep = -1,3 V; tpré = 120 s; Frequência: 60 Hertz. Os voltamogramas e suas correspondentes curvas de adição padrão indicaram que o uso do BiFE com a técnica Voltametria de Redissolução Anódica (ASV), no modo onda quadrada, indicaram que o procedimento é adequado, útil e sensível para a determinação de Cu²⁺ em biocombustíveis. Os experimentos realizados, pela adição sucessiva de alíquotas da solução padrão de Cu²⁺ proporcionaram uma resposta linear entre a corrente de pico e a concentração do íon metálico. Bons limites de detecção foram obtidos para a determinação do Cu²⁺ em Etanol combustível, biodiesel de óleo de soja e de sebo respectivamente (4,90x10ˉ⁸ mol Lˉ¹; 5,60x10ˉ⁸ mol Lˉ¹; 1,79x10ˉ⁸mol Lˉ¹). A exatidão foi avaliada através do teste de recuperação (recuperações de 85,6% a 97,05%). A precisão, expressa pelo coeficiente de variação (CV: entre 10% e 18%) foi considerada boa. O método foi aplicado com sucesso em amostras reais de biodiesel e Etanol combustível.
26
Garcia, Jean-Claude. « Equilibres de phases dans le système Cu-Bi-Se : modélisation des dépôts en phase vapeur des chalcogénures de bismuth ». Montpellier 2, 1991. http://www.theses.fr/1991MON20223.
Texte intégralRésumé :
Les materiaux thermoelectriques de type n sont constitues par des alliages multicomposants dont l'element essentiel est le seleniure de bismuth. Ils sont l'objet de ce travail. Une premiere partie presente une recherche cristallochimique prospective sur le systeme pseudobinaire cu#2se-bi#2se#3 incluant diagramme de phase experimental et etude des phases intermediaires. A cet effet, les techniques habituelles de la chimie du solide ont ete utilisees (dta, dsc, diffraction x). Deux phases intermediaires ont ete mises en evidence cu#3bise#3 et cubi#3se#5 et caracterisees par leur constante de mailles. Pour l'une d'elle, la structure cristalline a pu etre resolue sur monocrystal. Elle a ete discutee en analysant la stereoactivite de la paire libre du bismuth iii. La realisation de couches minces de bi#2se#3 n'a ete etudiee dans un but d'optimisation des caracteristiques thermoelectriques. Une modelisation des equilibres solide-vapeur pour la phase pure ainsi que pour son homologue tellure est presentee. A cet effet, les grandeurs thermodynamiques correspondant aux systemes presentes sont calcules. La comparaison avec des resultats experimentaux anterieurs et avec d'autres decoulant de la preparation de depots en jets moleculaires montrent un bon accord et la fiabilite des calculs. En application des resultats de caracterisation de couches sont presentes
27
Vodhanel, Mark E. « Texture improvements in the high-temperature superconducting Bi₂Sr₂Ca₁Cu₂Ox̳/Ag system via surface energy driven grain alignment ». Thesis, Massachusetts Institute of Technology, 2005. http://hdl.handle.net/1721.1/32838.
Texte intégralRésumé :
Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Physics, 2005.In title on t.p., double-underscored "x" appears as subscript.
Includes bibliographical references (leaf 40).
The relation between processing, microstructure, and material property was investigated in the high-temperature superconducting Bi₂Sr₂Ca₁Cu₂Ox̳/Ag system. Experiments were based on a theoretical surface energy model proposing enhanced texture of the oxide at the Ag interface after melt-processing. Two classes of samples were processed and compared. Bi-2212 powder was deposited on a thin-foil Ag surface and was melt-processed to yield a 20 ± 10 micron-thick superconducting layer. A subset of these samples were processed with an additional Ag surface pneumatically pressed on top of the superconducting layer before heat treatment. Critical current density (...) measurements were performed in liquid helium and we obtained values ranging from 5,900-36,700 A/cm². A 3-6 fold increase in ..., for samples with the second Ag interface was observed. X-ray diffraction provided a technique for quantifying grain alignment via the Lotgering factor, and indicated samples with the upper Ag interface possess a higher degree of texturing. Our results support the interfacial energy model that a high degree of texture exists at the Ag surface, and provide clear evidence linking materials processing, superconducting grain alignment, and critical current density. Disparities observed in J for similarly processed samples were believed to be a consequence of local regions of alignment and the presence of impurities.
by Mark E. Vodhanel.
S.B.
28
Faqir, Hakim. « Synthèse, croissance cristalline et caractérisations de quelques phases, supraconductrices ou non, dans le système (Bi,Pb)-Sr-Ca-Cu-O ». Aix-Marseille 1, 1995. http://www.theses.fr/1995AIX11042.
Texte intégralRésumé :
Ce travail porte sur deux formes potentiellement interessantes de materiaux supraconducteurs a haute temperature critique, a savoir les ceramiques et les monocristaux de cuprates a base de bismuth, bi#2sr#2cacu#2o#8 (2212) et (bi#1#,#6pb#0#,#4)sr#2ca#2cu#3o#1#0 (2223). Nous nous sommes plus particulierement interesse aux conditions de stabilite thermique et a la cinetique de formation de la phase (bi#1#,#6pb#0#,#4)sr#2ca#2cu#3o#1#0, en fonction de la composition initiale. Nous avons pu mettre en evidence plusieurs points: domaine thermique de synthese de la phase 2223 limite a quelques degres autour de 865 2c, formation de 2223 acceleree par la substitution du strontium par le calcium, les meilleurs resultats etant obtenus pour une composition initiale (bi#1#,#6pb#0#,#4)sr#1#,#7#5ca#2#,#2#5cu#3o#z qui conduit a 60% de 2223 en 24 h. L'etude de la croissance de cristaux de la phase bi#2sr#2cacu#2o#8, liee a celle de la fusion des ceramiques 2212, nous a permis de definir des conditions favorables a sa croissance cristalline: la preparation de bi#2sr#2cacu#2o#8 necessite un refroidissement lent entre 915 et 880c, domaine d'equilibre entre une phase liquide et les deux phases solides bi#2sr#2cuo#6 et (sr#1#-#xca#x)#2cuo#3. La presence d'un flux supplementaire de bi#2cuo#4 favorise non seulement la reaction entre les deux phases solides bi#2sr#2cuo#6 et (sr#1#-#xca#x)#2cuo#3, mais conduit a une recuperation plus aisee des cristaux de 2212 et, surtout, a une temperature critique t#c#(#0#) de 96 k, parmi les plus elevees de la litterature pour cette phase. Il est a noter la formation systematique d'une phase jaune, appartenant a la solution solide bi#2sr#3#-#xca#1#+#xo (-0,4#5 x 0,6#5), evitee seulement dans le cas de l'utilisation d'un flux de bi#2cuo#4. Enfin, une etude specifique des compositions sr#1#4cu#2#4o#4#1 et sr#3cu#5o#8#+#, phases pouvant apparaitre apres fusion du 2212, nous a permis d'attribuer les raies inconnues apparues dans les diagrammes x a haute temperature avant la fusion complete a la phase sr#3cu#5o#8#+#, cette composition etant monophasee contrairement a la premiere
29
新苗, 稔展. « Bi-Sr-Cu-O系2201相および関連化合物の合成と構造 ». 京都大学 (Kyoto University), 1999. http://hdl.handle.net/2433/181979.
Texte intégral
30
Truscott, Anthony D. « Low temperature scanning tunneling spectroscopy of proximity effect junctions formed on the layered superconductors NbSe₂ and Bi₂Sr₂Ca₁Cu₂O₈ / ». Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC IP addresses, 1999. http://wwwlib.umi.com/cr/ucsd/fullcit?p9930908.
Texte intégral
31
Duan, Qing. « The Effects of Rapid Heating and Cooling on the Composition, Structure, and Superconducting Properties of Bi-Sr-Ca-Cu-O Compounds ». PDXScholar, 1993. https://pdxscholar.library.pdx.edu/open_access_etds/1322.
Texte intégralRésumé :
Bulk and thin film samples of Bi₂₋[subscript x]Pb[subscript x]Sr₂Ca₂Cu₃O[subscript y] compounds were prepared by suitable methods. The thin film and bulk samples were exposed to argon gas at temperatures of about 2000 °C and pressures of about 300 atm. in a ballistic compressor (BC) and then cooled at a rate of about 10⁵ °C/sec. The samples before and after this treatment were examined and compared using a transmission electron microscope (TEM), a scanning electron microscope (SEM), an energy dispersive spectrometer (EDS) , and an x-ray diffractometer (XRD). Resistance and magnetic susceptibility measurements were made to determine changes in superconducting temperature Tc. Resistance and AC susceptibility measurements of bulk and thin film samples demonstrated that the Tc increased 3- 6 K after the BC treatment, and step-shaped curves were often observed in the resistance versus temperature graphs. The x-ray diffraction study revealed that the relative intensities of lines of the two high Tc phases clearly increased, and the relative intensities of lines of the low Tc phase decreased after the BC treatment. Scanning electron micrographs of the exposed samples showed that surface melting had occurred, and the BC treatment affected the surface of samples to a depth of about 10 μm. Energy dispersive spectral analysis showed that oxygen loss occurred in the exposure process. Transmission electron diffraction patterns showed that the crystal structure of the Bi-based compounds have an incommensurate modulation along the b-axis with different periods of 25.4 Å, 38.7 Å and 72.6 Å. After the BC treatment, the lattice parameters of superconductors did not change, but the relative intensities of spots changed, the modulation of 72.6 Å disappeared, and the density of twist boundaries increased. These observations suggest that the treatment changed the density of structural defects and the atomic arrangement. These studies tentatively indicate that the increase in structural defects was caused by oxygen loss. A very small oxygen loss increases the fraction of copper in CU‴ oxidation state, and thus increases the density of hole carriers in the Cu-O planes. This may be the reason why the Tc of Bi-based cuprate superconductors increased after the BC treatment.
32
Bestandji, Mustapha. « Mise au point d'une cellule en céramique (AL2O3 et BN) pour l'étude des propriétés de transport électronique d'alliages de métaux normaux réactifs : cas des alliages Cu-Ge, Mg-Sn, Bi-Mg et Bi-Ge ». Metz, 2000. http://docnum.univ-lorraine.fr/public/UPV-M/Theses/2000/Bestandji.Mustapha.SMZ0017.pdf.
Texte intégralRésumé :
Le présent travail a été consacré à l'étude du transport électronique de métaux et d'alliages métalliques à l'état liquide notamment à base de magnésium dont certains présentent une transition métal-non métal en fonction de la concentration. Les réactions physico-chimiques des cellules classiques en quartz avec le magnésium liquide ont nécessité la mise au point d'un dispositif original de nouvelles cellules de mesures en vue de l'étude simultanée de la résistivité et du pouvoir thermoélectrique absolu de métaux liquides fortement réactifs. Les résultats expérimentaux obtenus ont été interpolés en utilisant la formule de Ziman étendue actualisée par l'utilisation de la théorie de la densité de la fonctionnelle (DFT) dans le cadre de l'approximation de la densité locale (LDA). Celle-ci a été corrigée par l'approximation du gradient généralisé (GGA 1996) pour estimer la contribution de l'échange et de la corrélation. Les résultats expérimentaux des corps purs, sont discutés dans le cadre de ce formalisme. La dépendance en température de la résistivité et du pouvoir thermoélectrique liquide du germanium a fait l'objet d'une publication au Journal of physics of condensed matter en 1999. Nous présentons les mesures de PTA des alliages Bi-Ge et Cu-Ge en fonction de la température et de la composition. Ceux-ci n'ont jamais été étudiés auparavant. Les résultats expérimentaux sont interprétés de manière satisfaisante par le formalisme théorique cité ci-dessus. L'alliage Bi-Mg présente un comportement tout à fait particulier. Sa résistivité est analogue à celle de semi-conducteurs très près de la composition stoechiométrique, par contre le PTA est presque typique de celui de métaux même s'il présente un changement de signe à la composition Mg60Bi40. Nous présentons aussi des mesures de résistivité d'alliages liquides Mg-Sn, jamais effectuées auparavant à notre connaissance. Cet alliage présente un comportement beaucoup plus métallique
33
Zaragoza, Alain. « Cables multifilamentaires supraconducteurs à base de (Bi, Pb)₂Sr₂Ca₂Cu₃O₁₀₊ð : barrières résistives, diffusion d'oxygène et formation de la phase ». Chambéry, 2003. http://www.theses.fr/2003CHAMS031.
Texte intégralRésumé :
Le travail de cette thèse porte sur les câbles supraconducteurs à base de Bi2Sr2Ca2Cu30x (Bi-2223). De tels rubans sont constitués d'une gaine d'alliage Ag-Mg dans laquelle est placée le supraconducteur. En application de transport de courant, les pertes électriques doivent être minimisées car l'ensemble du ruban se comporte alors comme un filament unique. La suppression de ces courants de couplage est réalisée en torsadant le câble et en augmentant la résistivité de la matrice entre les filaments. Ce point est à l'origine d'un nouveau concept de conducteurs composites constitués de poudres supraconductrices, d'une barrière résistive et de la gaine métallique. Dans ce travail, trois axes d'études ont été développés : proposer un matériau comme barrière résistive, déterminer les coefficients de diffusion de l'oxygène dans les matériaux utilisés comme gaine, préciser les conditions optimales de formation de Bi-2223. Deux matériaux pour barrières ont été étudiés: le zirconate de strontium et les vanadates de strontium. Le premier a été synthétisé par voie sol-gel, ce qui permet d'obtenir des grains de taille submicroniques et ainsi réduire au maximum les contraintes mécaniques au cours de la fabrication des câbles supraconducteurs. En ce qui concerne les vanadates de strontium, nous avons été amenés à l'étude thermodynamique du diagramme d'équilibre entre phases srO-v2Os. Nous avons montré que Sr4V2O9 est la dernière phase intermédiaire stable riche en srO dans ce système. A l'aide d'un montage expérimental novateur développé pour cette étude, nous avons pu déterminer que les coefficients de diffusion dans les alliages étaient près de mille fois plus faibles que dans l'argent pur. Dans la dernière partie, nous avons abordé la cinétique de formation de Bi2Sr2Ca2Cu3Ox dans une atmosphère de ~ 7%O2/N2. Nous avons confirmé que la formation suivait un mécanisme de nucléation-croissance, identique à celui observé dans une atmosphère avec une pression partielle en oxygène différenteThis work is focused on Bi2Sr2Ca2Cu3Ox based (Bi-2223) superconducting cables. This tapes are constituted by a cylindrical silver-magnesium sheath embeding superconducting ceramic. Aternative courant lasses have to be minimized because the multifilament tape is considered as a single filament. Twisting cables and adding resistive barrier between each monofilaments are known to decrease the coupling courant. This is the starting point for a new concept for conductor composites which include the superconducting powder, the resistive barrier and the metallic sheath. The three aims of the study were to propose a material for resistive barrier, to determine diffusion coefficients of oxygen through the material sheath and the formation conditions of Bi-2223 phase starting from precursors provided by the two industrial partners, Nexans (France) and Vacuumschmelze (Germany). Firstly, two materials as resistive barriers have been studied : strontium zirconate and strontium vanadates. The foremost was synthetized by a sol-gel method providing submicronic grains size and reduce mechanical stress during the cable process. Conceming strontium vanadates, the thermodynamical study of the srO-V2O5 phases equilibrium diagramm was necessary. We have shown that Sr6V2O11 is not a thermodynamic stable compound, Sr4V2O9 is the last phase rich in SrO in the system. The use of these materials as resistive barrier in superconducting cables performed by Nexans bas been discussed. Diffusion coefficients of oxygen have been measured using a new experimental assembly based on the "time lag permeation" method. We shown that in Ag-Mg alloys, these coefficients are three orders of magnitude lower than in pure silver. Finnaly, we found that the formation kinetic of Bi-2223 in a pO2=7% atmosphere is limited by a nucleation- growth mecanism, similarly with studies performed in other partial oxygen pressure
34
Yu, Zeming. « Fabrication d'un nouveau substrat bi-métallique Cu-Ni et dépôt de films de La2Zr2O7 (LZO) sur substrat métallique par procédé chimique en solution ». Phd thesis, Université Joseph Fourier (Grenoble), 2008. http://tel.archives-ouvertes.fr/tel-00376983.
Texte intégralRésumé :
Le Coated Conductor est un empilement de couches tampon sur un substrat, il est composé d'un substrat métallique, de couches tampon, d'une couche d'YBCO et d'une couche protectrice. Développer de bons substrats métalliques, simplifier l'architecture des couches tampon et trouver des méthodes de fabrication d'YBCO économiques sont les sujets essentiels de ce domaine. On a développé un nouveau substrat bimétallique Cu-Ni par dépôt électrochimique d'une couche de Ni sur un ruban de cuivre texturé et on discute comment déposer un film de La2Zr2O7 (LZO), de même texture, sur un substrat métallique par un processus chimique en solution (CSD). La fabrication de rubans de Cu texturé par un procédé de laminage-recristallisation est présentée en premier, puis on s'intéresse au dépôt électrochimique du Ni sur ces rubans. La stabilité thermique de la texture et les propriétés magnétiques de ces substrats Cu-Ni est discutée. Le dépôt d'une couche tampon de LZO texturée sur ces substrats par le procédé CSD confirme leur intérêt potentiel pour les Coated Conductors. Le dépôt de couches de LZO sur divers substrats métalliques, la préparation de précurseurs et des substrats, la croissance épitaxiale de couches tampon de LZO sont discutés en détail. On montre que l'acetylacétonate dissout dans l'acide propionique est une bonne solution. Une couche de S de structure c(2x2) à la surface du substrat permet le contrôle de l'orientation initiale des couches de LZO. Le carbone résiduel issu de la synthèse de LZO est un facteur inhibant la croissance des grains de LZO mais son gradient sous la surface est utile. La maitrise de l'ensemble de ces facteurs permet la formation de couches de haute qualité.
35
BESTANDJI, MUSTAPHA GASSER JEAN GEORGE. « MISE AU POINT D'UNE CELLULE EN CERAMIQUE (AL 2O 3 ET BN) POUR L'ETUDE DES PROPRIETES DE TRANSPORT ELECTRONIQUE D'ALLIAGES DE METAUX NORMAUX REACTIFS. CAS DES ALLIAGES CU-GE, MG-SN, BI-MG ET BI-GE / ». [S.l.] : [s.n.], 2000. ftp://ftp.scd.univ-metz.fr/pub/Theses/2000/Bestandji.Mustapha.SMZ0017.pdf.
Texte intégral
36
Vanlathem, Eric. « Synthèse, caractérisations et étude par diffusion quasiélastique des neutrons du système supraconducteur à haute température critique Bi-Sr-Ca-Cu-O dope au fer ». Doctoral thesis, Universite Libre de Bruxelles, 1992. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/212916.
Texte intégral
37
Pasler, V. [Verfasser]. « Thermische Ausdehnung von entzwillingten Y₁₋ₓCaₓBa₂Cu₃Osub(y)-Einkristallen und Bi₂Sr₂CaCu₂Osub(y)-Einkristallen : Kritische Fluktuationen und uniaxiale Druckabhängigkeiten / V. Pasler ». Karlsruhe : KIT-Bibliothek, 2000. http://d-nb.info/1198219866/34.
Texte intégral
38
Müller, Cornelia. « Der Einfluß der Mikrostruktur auf die supraleitenden Eigenschaften von Bi 2+y Sr 2-x Ca 0,9+x Cu 2 O 8+delta -Einkristallen ». Stuttgart : Univ, 2000. http://www.bsz-bw.de/cgi-bin/xvms.cgi?SWB8565779.
Texte intégral
39
Wang, Wei, et 王. 暐. « Cu/Bi2Te3 and Ni/Bi2Te3 interfacial reactions and Bi-Cu-Te and Bi-Ni-Te phase diagrams ». Thesis, 2018. http://ndltd.ncl.edu.tw/handle/g99c6f.
Texte intégral
40
Vishnubhotla, Prasad. « Transport Properties Of Polycrystalline Bi-Sr-Ca-Cu-O And Bi-Pb-Sr-Ca-Cu-O High Temperature Superconductors ». Thesis, 1997. http://etd.iisc.ernet.in/handle/2005/1829.
Texte intégral
41
Tu, Hui-Shan, et 涂惠珊. « Bi and Bi/Cu Nanoparticles on Tribological Properties of Lubricating Oil SAE-30 ». Thesis, 2014. http://ndltd.ncl.edu.tw/handle/99au34.
Texte intégralRésumé :
碩士國立臺北科技大學
製造科技研究所
102
This study aimed to improve the lubrication performance of lubricating oil by adding Bi and Bi/Cu nanoparticles into mineral oil SAE-30. This study carried out tribological test using a pin-on-disk tester that meets ASTM G99 standards. Focusing on Bi and Bi/Cu nanolubricants at different concentrations, this study analyzed the tribological features of the nanolubricants with additive of Bi and Bi/Cu nanoparticles, and then acquired Stribeck curves of three lubrication regions. Besides, this study tested the worn surface of sample, including appraisal of its ingredients and appearance of worn surface. The differences of fiction coefficient, wear scar diameter, morphology of worn surface and viscosity was analyzed. Experimental results show that adding Bi or Bi/Cu nanoparticles into lubricating oil can enhance wear resistance and reduce friction coefficient. Under the condition of Bi nanoparticles at concentration 0.1 wt%, the friction coefficient and wear scar diameter can be reduced by 68.9 % and 38.6 % respectively comparing to pure lubricating oil. In addition, under the condition of Bi/Cu nanoparticles at concentration 0.2 wt%Bi+0.08 wt%Cu, the friction coefficient and wear scar diameter can be reduced by 71 % and 50.95 % respectively comparing to pure lubricating oil. Furthermore, after load is applied, experimental results show that the lubricant added with Bi nanoparticles can effectively enhance the oil’s ability in wear resistance. Besides, through SEM photographs, it is proved that Bi and Cu nanoparticles produce filling and sedimentary effects on the worn surface.
42
Shih, Han-Wei, et 石漢偉. « Phase equilibria of the Sn-Bi-Au and Sn-Bi-Cu ternary systems ». Thesis, 2008. http://ndltd.ncl.edu.tw/handle/ynfwuf.
Texte intégralRésumé :
碩士國立臺北科技大學
化學工程研究所
96
The Sn-Bi solder is a very common lead-free solder. Copper and gold are generally used as the substate and electroplating material on PCB, respectively. They are also used as the under-bump metallurgy (UBM) of the flip chip package. This study contains two parts: one is the isothermal section of the Sn-Bi-Au ternary phase diagram at 100℃ and 120℃, respectively；and the other is the isothermal section of the Sn-Bi-Cu ternary phase diagram at 120℃ and 400℃, respectively. Those diagrams were obtained from scanning electron microscopy (SEM) coupled with backscattered electron image (BEI) and X-ray diffractometer. Also, electron probe microanalysis (EPMA) was applied to determine the quantitative composition of the individual element, which made the experiment results more comprehensive. In Sn-Bi-Au ternary system, experiment results showed that a ternary compound of SnAu4Bi3 was found at both temperatures, in addition to expected the binary phase diagram of Bi-Au, Bi-Sn and Sn-Au. In Sn-Bi-Cu ternary system at 400℃, experiment results showed that the liquid phase was in equilibrium with Cu6Sn5, Cu3Sn, and Cu4Sn phases; experiment results at 120℃ showed that the Bi phase was a very stable phase and was in equilibrium with Cu6Sn5, Cu3Sn, Sn and Cu phases.
43
Yen, Wan-Ting, et 顏婉婷. « Phase diagram of Bi-Cu-Te and Thermoelectric properties of Cu doped Bi2Te3 alloys ». Thesis, 2018. http://ndltd.ncl.edu.tw/handle/ekssxf.
Texte intégralRésumé :
碩士國立中山大學
材料與光電科學學系研究所
106
Thermoelectric material (TE) could convert waste heat directly into electricity, and therefore it could pave the way toward the environmental sustainability. The layered-structure Bi2Te3, which crystallize in a rhombohedral symmetry, show anisotropic transport properties, and are the most well-established room-temperature TE materials. Herein we aim to tune the thermal/electrical transport properties of the Bi2Te3-based alloys, by incorporating minor amount of Cu, to form a series of Cu-doped Bi2Te3 alloys. The homogeneity regime, phase stability and microstructural evolution are elaborated by establishing the 523K isothermal section and liquidus projection of ternary Bi-Te-Cu system, using the thermally-equilibrated or solidified alloys. In addition, the TE properties of selective Cu-doped Bi2Te3 alloys that grown by the Bridgman method suggest that the small deviations in the starting compositions could lead to the huge the difference in the resultant TE performance. At 300 K, the highest peak zT for p-type ((Bi2Te3)0.99(Cu2Te)0.01) and n-type (Bi2¬Cu0.01Te2.99) Cu-containing Bi2Te3 are zT~1.2 and zT~1.7, respectively.
44
Tsai, Chung Dean, et 蔡宗典. « Tunneling Studies of Bi-Sr-Ca-Cu-O Superconductor ». Thesis, 1993. http://ndltd.ncl.edu.tw/handle/68086018914104706280.
Texte intégralRésumé :
碩士中原大學
應用物理學系
82
This thesis is focused on the fabrication of the bulk and thin film of the high-Tc superconductor Bi-Sr-Ca-Cu-O( BSCCO ) and its tunneling spectroscopy. Following the cyclic processes of mixing powder, grinding, calcining, pressing and sintering, we got the superconductive bulk of BSCCO with Tco = 105 K. We then used the bulk as our target, by the magnetron RF sputtering technique, we sputtered thin film on the MgO(100) single- crystal substrate. By changing the sputtering conditions( substrate temperature , sputtering gas and sputtering pressure ), we have observed the effects of the sputtering parameters on the ciritical temperature (Tc) and the morphology of the films. For the in-site sputtering method, we got BSCCO films with good morphology, but the Tc could not get better, while for post- annealing method, we could improve the Tc but the morphology of the film suffered. In order to get the energy gap of the BSCCO superconductor, we fabricated planar tunneling junctions with Pb as our counterelectrode. The native tunneling barrier(I) was formed through the interaction of Pb and BSCCO. We then conducted tunneling experiment of the sandwich-type BSCCO/I/Pb junction. The characteristic conductance curves exhibited zero- bias anomaly. Gap-like structures were observed at bias voltage V = 20-40 mV, and showed different gap values for different structure phases, with Δ2212= 40 meV、Δ2223 = 20 meV, corresponding to the reduced energy gap 2Δ2212/kBTc = 11 and 2Δ2223/kBTc = 6.4, respectively. We also observed the gap strucrure of the counterelectrode(Pb) with ΔPb = 1.92 meV.
45
CAI, ZHONG-DIAN, et 蔡宗典. « Tunneling studies of Bi-Sr-Ca-Cu-O superconductors ». Thesis, 1993. http://ndltd.ncl.edu.tw/handle/08629680988073128484.
Texte intégral
46
Nomssi, Nzali Jacques Hubert Christian [Verfasser]. « Nahordnung und mittelreichweitige Ordnung in den binären Legierungsschmelzen : Ag-Bi, Bi-Cu, Cu-Pb, Ga-Tl / vorgelegt von Jacques Hubert Christian Nomssi Nzali ». 2000. http://d-nb.info/972279040/34.
Texte intégral
47
ZHANG, LIE-ZHENG, et 張烈錚. « Bi-Ca-Sr-Cu-O超導性研究 ». Thesis, 1990. http://ndltd.ncl.edu.tw/handle/05993585701237935013.
Texte intégral
48
Tsai, Chih-Ming, et 蔡志明. « The Study of Sn-Bi-Cu Solder Microseructure by Vacuum Smelting ». Thesis, 2012. http://ndltd.ncl.edu.tw/handle/35038586939573419280.
Texte intégralRésumé :
碩士國立勤益科技大學
機械工程系
101
This study is to confer the microstructure of the Sn-Bi-Cu lead-free alloy’s interface , and also confer the effect of contact angle on wetting , another time we also compare with the Sn-Ag-Zn alloys between their difference . First we made 10 difference Sn-Bi-Cu ternary alloy , and then use vacuum melting to smelt the ternary alloy so that can get the ternary lead-free alloy for confer the variation of microstructure how to affect the contact angle . When analysis the different proportion of Sn-Bi-Cu alloy’s contact angle , we can know that when the Cu increased by more than 3wt.% , the alloy’s contact angle will be more and is also mean the wetting will be also become weak , that is because when the Cu is increase , and the Sn-Bi-Cu metal alloy also increase , and it will beinfluence the contact angle . But when the same proportion alloy smelt in 120℃ , we can find the contact angle became larger , that is because without heat treatment before the alloy have two Cu-Sn intermetallic compounds , when heat treatment done , there is Cu-Sn and slowly goes into Sn phase . Cu-Sn intermetallic compounds will be extended to the abundant tin , increase in the Cu-Sn compound area , resulting in larger contact angle . In this study , Cu-Sn intermetallic compounds will affect the alloy’s wetting.
49
GUO, FANG-ZHI, et 郭芳志. « Fabrication of the high Tc superconductor Bi-Ca-Sr-Cu-O ». Thesis, 1990. http://ndltd.ncl.edu.tw/handle/50156035635132052817.
Texte intégral
50
Ferreira, José Jorge do Amaral. « Transition Metals Thermal Crystal Physics : Cu-Sb-S, Cu-Li-Mg, Bi-Sn-Zn and Al-Fe-Ti ». Doctoral thesis, 2012. https://repositorio-aberto.up.pt/handle/10216/72665.
Texte intégral