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Síntese e avaliação de arranjos supramoleculares de triazenos monocatenados e complexos com os cátions Co3+, Cu2+, Ag+ e Au+ / Synthesis and evaluation of the supramolecular arrangements of ligands triazenes and complexes with Co3+, Cu2+, Ag+ and Au+ cationsBehm, Mariana Boneberger 31 August 2010 (has links)
Conselho Nacional de Desenvolvimento Científico e Tecnológico / Triazenes ligands substituted by terminal aryl groups in the diazoamine chain [ N=N N(H) ] containing NO2 group substituted in different position and ortho C(O)NH2 on aryl ring was evaluated on the occurrence of intermolecular interactions through hydrogen links. The research was based primarily on X-ray diffraction in
single crystal to analyze structurally the occurrence of self-assembles supramolecular architectures on solid state. This work presents the synthesis and investigation of molecular and crystal structure of eleven new compounds. The pre-ligands 1-(2-amidofenil)-3-(2-nitrofenil)triazeno (I), 1-(2-amidofenil)-3-(4-nitrofenil)triazeno (II) e 1-(2-amidofenil)-3-(3-nitrofenil)triazeno (III), the cobalt(III) complexes: {Co[C(O)NHC6H4NNNC6H4NO2](C2H8N2)2}{Cl}.CH3OH (1), {Co[C(O)NHC6H4NNNC6H4NO2](C2H8N2)2}{Cl}.H2O (2) and {Co[C(O)NHC6H4NNNC6H4NO2](NH3)4}{NO3}.H2O (3), and silver(I) complexes: {Ag[C(O)NH2C6H4NNNC6H4NO2](C2H8N2)}{[C(O)NH2C6H4NNN(H)C6H4NO2]} (4) and {Ag[C(O)NH2C6H4NNNC6H4NO2](C2H8N2)]} (5), and cupper(II) complexes: {Cu4[C(O)NHC6H4NNNC6H4NO2]2[(OCH3)4]} (6) and gold(I) complexes: {Au[C(O)NH2C6H4NNNC6H4NO2](PC18H15)}{C5H5N} (7) e Au[C(O)NH2C6H4NNNC6H4NO2](PC18H15)] (8). Other complementary techniques were used to characterize the compounds, such as: infrared spectroscopy, 1H nuclear magnetic resonance spectroscopy, ultraviolet-visible spectroscopy, mass spectrometry, Raman spectroscopy and thermogravimetric analysis. / Ligantes triazenos substituídos nos grupos arilas terminais na cadeia diazoamínica [ N=N N(H) ] contendo os substituintes NO2 em diferentes posições e o grupo C(O)NH2 orto substituído ao anel foram avaliados quanto à ocorrência de
interações intermoleculares através de ligações de hidrogênio. A investigação baseou-se principalmente na difração de raios-X em monocristal para analisar estruturalmente a formação de arranjos supramoleculares no estado sólido. Este trabalho apresenta a síntese e a investigação da estrutura cristalina e molecular de onze compostos inéditos: os pré-ligantes 1-(2-amidofenil)-3-(2-nitrofenil)triazeno (I), 1-(2-amidofenil)-3-(4-nitrofenil)triazeno (II) e 1-(2-amidofenil)-3-(3-nitrofenil)triazeno (III), os complexos de cobalto (III): {Co[C(O)NHC6H4NNNC6H4NO2](C2H8N2)2}{Cl}.CH3OH (1),
{Co[C(O)NHC6H4NNNC6H4NO2](C2H8N2)2}{Cl}.H2O (2) e
{Co[C(O)NHC6H4NNNC6H4NO2](NH3)4}{NO3}.H2O (3), os de prata (I): {Ag[C(O)NH2C6H4NNNC6H4NO2](C2H8N2)}{[C(O)NH2C6H4NNN(H)C6H4NO2]} (4) e {Ag[C(O) NH2C6H4NNNC6H4NO2](C2H8N2)]} (5), o de cobre (II):
{Cu4[C(O)NHC6H4NNNC6H4NO2]2[(OCH3)4]} (6) e os de ouro (I): {Au[C(O)NH2C6H4NNNC6H4NO2](PC18H15)}{C5H5N} (7) e
Au[C(O)NH2C6H4NNNC6H4NO2](PC18H15)] (8). Outras técnicas complementares foram utilizadas para caracterizar os compostos, como: espectroscopia de infravermelho, ressonância magnética nuclear 1H, espectroscopia do ultravioleta visível, espectrometria de massa, espectroscopia Raman e análise termogravimétrica.
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Structural, Optical and Electrical Studies on Multi-Functional Organic Single CrystalsSaripalli, Ravi Kiran January 2017 (has links) (PDF)
In this thesis, the physical properties of certain multi-functional organic crystals were studied in detail. This study involves the growth of single crystals of Glucuronic acidγ-lactone (GAL), Imidazoliumtartarate (IMLT), (Bis)imidazoliumtartarate (BIMLT), and Diisopropylammonium iodide (DPI) and investigations of their optical, dielectric, piezoelectric, pyroelectric, and ferroelectric properties as a function of temperature and dependence on crystal structure in these organic crystals.
Piezoelectric resonance was observed at certain frequencies when dielectric constant was monitored along the b-plate of GAL crystals. The electro-mechanical coupling coefficient estimated at the resonance near 1 MHz frequency revealed an exceptionally large value in GAL similar to that in inorganic lead titanate. The dependence of the piezoelectric resonance frequency on temperature was studied in detail. These crystals showed excellent second- and third-order nonlinear optical properties as well as high laser damage threshold. The high values of χ(2) andχ(3), laser damage threshold, and low UV cut-off makes GAL crystals an interesting prospect for NLO and laser applications. Towards this goal, GAL crystals were studied in detail with regard to determination of directions of dielectric axes, optic axes, and collinear phase-matching.
Single crystals of another promising NLO organic crystal, IMLT were also grown which showed interesting dielectric, piezoelectric, and NLO properties. The dielectric dispersion with temperature provided an insight to the polarization mechanisms. Like GAL, IMLT also exhibits piezoelectric resonance. The existence of only one easy axis of vibration in IMLT enabled the candidate to identify the first resonance peak as corresponding to the fundamental mode of oscillation in the sample. This also helped to determine many piezoelectric parameters. By angular phase matching, one direction of phase matching in IMLT was identified. The conversion efficiency of IMLT along this direction was determined which was high in comparison to that in a standard KDP crystal. At piezoelectric resonance frequencies, the electro-optic response due to photo-elastic contributions is enhanced. Single crystals of organic ferroelectric BIMLT were grown by mixing two moles of imidazole with one mole of l-tartaric acid. The controversy with regard to the phase transition temperature of BIMLT was clarified by the DSC and structural analysis in this work. Previously, studies on BIMLT were limited to polycrystalline samples and single crystals with inclusions primarily due to the difficulty in growing good quality single crystals from aqueous solution. However, by experimenting the growth process using different solvents, good quality single crystals were achieved without the trapping of mother solution. This remarkable find is a notable result in these crystals for ferroelectric applications. The mechanism of ferroelectricity in BIMLT is mainly attributed to the transfer of protons along N–H---O hydrogen bonds in the direction of b-axis.
Interestingly, the values of spontaneous polarization and Curie-temperature in the organic ferroelectric material DPI were significantly high and comparable to several popular inorganic ferroelectrics. The polarization obtained in this material is the highest among reported organic ferroelectrics. In addition to the high Curie temperature and spontaneous polarization, there were unique phase transitions that were revealed in DPI. The mechanism of ferroelectricity is quite complex, mainly being displacive type on account of the change in orientation of dipoles with electric field. Some contribution to ferroelectricity comes from the order-disorder nature of Nitrogen atom.
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Synthesis of new cocrystal solid form of fluconazole-fumaric acidOwoyemi, Bolaji Charles Dayo 29 September 2015 (has links)
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Previous issue date: 2015-09-29 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Pharmaceutical cocrystals are multicomponent crystalline solids comprised of
an active pharmaceutical ingredient (API) and one or more co-formers
interacting through hydrogen bonding or other weak interactions like the π-stack
and van der Waals interactions. Fluconazole (FLZ) is a triazole antifungal drug
used in the treatment and prevention of superficial and systemic fungal
infections. It is also used to prevent and treat meningitis. Cocrystallization is an
alternative approach for enhancement of drug. It can be performed using neat
grinding, solvent assisted grinding, solvent evaporation, cooling evaporation
and slurry cocrystallization. In this work, a new cocrystal Fluconazol-Fumaric
acid monohydrate was synthesized via 1:1 stoichiometric amount of FLZ and
FUM at different conditions. The characterization of the synthesized cocrystals
was achieved using Raman spectroscopy, differential scanning calorimetry,
powder X-ray diffraction and single crystal X-ray diffraction. The results
obtained for the characterization of the samples showed some obvious
differences among the spectra, diffractograms and thermograms. The single
crystal X-ray diffraction analysis of the new structure shows a cocrystal where
the fluconazole molecules are attached to the fumaric acid and water molecules
respectively through hydrogen bonds, gave unique cell dimensions for an
assumed structure C17H18F2N6O6 with a space group of P21/n, a = 17.053(3) Å,
b = 5.5995(10), c=21.154(3), α = 90°, β=105.418(4)°, γ= 90°, V = 1947.3(6) Å3.
This work is the first to report a monohydrate cocrystal structure of fluconazole
and fumaric acid. / Cocristais farmacêuticos são sólidos cristalinos multi-componentes compostos
de um ingrediente ativo farmacêutico (API) e um ou mais co-formadores
interagindo através de ligações de hidrogênio ou outras interações fracas como
as π-stack e Van der Waals. Fluconazol (FLZ), é um fármaco anti-fúngico
triazol utilizado no tratamento e prevenção de infecções fúngicas superficiais e
sistémicas. É também utilizado para prevenir e tratar a meningite.
Cocristalização é uma abordagem alternativa para melhorar as propriedades de
fármacos. Pode ser realizada através de moagem a seco, moagem assistida
por solvente, evaporação de solvente e cristalização em suspensão. Neste
trabalho, um novo co-cristal Fluconazol-Ácido Fumarico monohidrato foi
sintetizado utilizando uma estequimetria 1:1 em diferentes condições. A
caracterização dos co-cristais sintetizados foi realizada utilizando
espectroscopia Raman, calorimetria exploratória diferencial, difração de raios-X
em pó é por monocristal. Os resultados obtidos para a caracterização das
amostras mostrou algumas diferenças obvias entre os espectros, difratogramas
e termogramas. A difração de raios-X de monocristal mostrou uma nova
estrutura onde as moléculas de fluconazol estão ligadas ao ácido fumárico e a
uma molécula de água através de ligações de hidrogênio, originando uma
estrutura única C17H18F2N6O6 de grupo espacial P21/n e dimensões da célula
unitária a = 17.053(3) Å, b = 5.5995(10), c=21.154(3), α = 90°, β=105.418(4)°,
γ= 90°, V = 1947.3(6) Å3. Este trabalho é o primeiro a relatar uma estrutura de
co-cristal mono-hidrato de fluconazol e acido fumárico.
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Introdução aos métodos de determinação de estruturas por difração de raios-X em monocristais: aplicação a alguns complexos de lantanídeos e metais de transição com ligantes orgânicos / An introduction to the methodology of structure determination by single crystal x-ray diffraction: applications to some complexes of lanthanides and transition metals with organic ligandsGlaucius Oliva 14 October 1983 (has links)
As estruturas cristalinas dos complexos Ln(ClO4)3.6[PONH2(C6H5)2] onde Ln=Eu, La, Cu[NH2(CH3)2CCO2]2, NiBr2.4[AsO(C6H5)3].8H2O (verde) e NiBr2.4[AsO(C6H5)3].1,5(CH3C6H5).H2O (alaranjado) bem como do ligante PONH2(C6H5)2 foram determinadas por difração de raios-X. Os complexos envolvendo íons lantanídeos refinaram a fatores R finais de R(Eu)=0,125, e R(La)=0,133 e foram encontradas a seguintes características principais: a) o sistema cristalino é cúbico; b) a coordenação do cátion é feita por seis átomos de oxigênio dos ligantes em configuração octaédrica (Eu) e antiprismática trigonal (La) com as terras raras em posições de alta simetria (23 para Eu e 3 para La); c) o restante das estruturas apresentam diferentes graus de desordem. À luz da sua configuração geométrica, a presença de uma forte banda 5Do-7F2 no espectro de fluorescência do complexo de Eu, proibida por considerações de simetria, é explicada como decorrente de acoplamentos vibrônicos. O desdobramento da linha υP=0 do espectro de infravermelho do coplxo de La é atribuído à presença de grupos P=0 não equivalentemente ligados a terra rara devido à desordem desta. O composto envolvendo o íon Cu(II) (fator R final 0,053) cristaliza no sistema monoclínico com os complexos se empacotando em camadas paralelas ao plano cristalino (100) com redes de pontes de H intracamada e com francas interações entre camadas consecutivas, o que explica o comportamento magnético quasi-bidimensional observado nestes cristais. O complexo de Ni(II) de coloração verde (fator R final 0,039) apresenta o íon metálico sobre um centro de simetria coordenado por seis moléculas de água numa conformação octaédrica distorcida, as quais estão ligadas aos grupos tfaso[AsO(C6H5)3] e íons brometo por fatores pontes de H. No complexo de coloração alaranjada (fator R final 0,087) o cátion está pentacoordenado com os quatro oxigênios dos ligantes tfaso formando a base de uma pirâmide quadrangular e um ânion Br- ocupando a quinta posição. Como uma conseqüência da resolução e refinamento da estrutura do complexo de Eu, a estrutura cristalina do ligante PONH2(C6H5) puro foi também determinada e refinada a um fator R de 0,033. / The crystal structure of the complexes Ln(ClO4)3.6[PONH2(C6H5)2] where Ln=Eu, La, Cu[NH2(CH3)2CCO2]2, NiBr2.4[AsO(C6H5)3].8H2O (green), NiBr2.4[AsO(C6H5)3.1,5(CH3C6H5).H2O (orange) and of the ligand PONH2(C6H5)2 have been determined by X-ray diffraction. The complexes involving lanthanide ions refined to final R factors of R(Eu)=0.125 and R(La)=0.133 and the following main features were found: a) the crystal system is cubic; b) the cation is coordinated to six ligand oxygens in octahedral earths on position of high symmetry (23 for Eu and 3 for La); c) the rest of the structures shows different degrees of disorder. In the light of the geometrical configuration, the occurrence of a strong band 5Do-7F2 in the fluorescence spectrum of the Eu complex, forbidden on symmetry grounds, is interpreted as a consequence of vibronic coupling. A splitting of the infrared υP=0 band in the La complex is attributed to the presence of P=0 goups non-equivalently bonded to the rare earth due to the disorder of this atom. The compound involving the Cu(II) ion (final R factor of 0.053) crystallizes in the monoclinic system with the complexes packed in layers parallel to the (100) crystal plane, with intralayer nets of H bonds and weak interactions between consecutive layers, which explains the quasi two-dimensional magnetic behavior observed in these crystals. In the green Ni(II) complex (final R=0.039), the metallic ion is sited on a center of symmetry and is octahedrally coordinated to six water molecules which are hydrogen bonded to the tfaso[AsO(C6H5)3] groups and the bromide ions. In the orange complex (final R=0.087) the cation is pentacoordinated with the four oxygens of the tpas ligands forming the basis of a quadrangular pyramid and one Br- anion in the fifth position. As a by product in the solution and refinement of the Eu complex structure, the crystal structure of the pure ligand PONH2(C6H5) was also determined and refined to a R-factor of 0.033.
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Estudos por RPE de um radical nitróxido em monocristal: interação com prótons e relaxação eletrônica / EPR studies of a nitroxide radical in a single crystal: proton interactions and electronic relaxationAntonio Alonso 27 May 1986 (has links)
No presente trabalho foram estudados os espectros de RPE de um radical nitróxido, 4-hidroxi-2,2,6,6-tetrametilpiperidina-l-oxil (TEMPOL, 11), introduzido como impureza em uma matriz diamagnética, 4-hidroxi-2,2,6,6-tetrametilpiperidina (I), de estrutura conhecida. O uso do radical deuterado, 4-hidroxi-2,2,6,6 -tetrametilpiperidina-d17-l-oxil (PD-TEMPOL, 111) mostrou um aumento considerável na resolução dos espectros para a maioria das orientações do campo magnético. A interação do grupo paramagnético N-O com os prótons vizinhos foram estudadas e os tensores superhiperfinos de dois prótons fortemente acoplados foram determinados. Um desses prótons forma ponte de hidrogênio com o grupo N-O e a distância estimada é 2,09ª°. Os autovalores do tensor são: -5,2; 5,4 e -5,1 gauss. O segundo próton está mais distanciado do radical e provavelmente não forma ponte com o radical. Os valores nas direções principais são: 2,0; -1,7;e -2,7 gauss. Com a finalidade de estudar o envolvimento dos prótons na relação eletrônica dos radicais foram estimados os tempos de relaxação T1 e T2 no intervalo de temperatura de -160 a 25°C através do método de saturação continua. Foram obtidos os valores em diversas orientações para os radicais protonado (II) e deuterado - (III) para compará-los. Os valores de T2 obtidos são praticamente constante no intervalo de temperatura onde foram medidos e sistematicamente são maiores para o radical deuterado. O tempo de relaxação spin-rede, T1 é dependente da orientação para ambos os radicais. Em geral é obtida urna dependência linear de T1-1 versus T que foi explicada considerando um mecanismo de relaxação por tunelamento dos protons vizinhos entre dois poços de potenciais. Para o radical protonado é observada uma descontinuidade na curva de T1-1 versu T na região de -60°C; para o radical deuterado - isto é observado somente para algumas orientações. Este comporta mento poderia ser explicado como devido o congelamento da vibração das pontes de hidrogênio em torno desta temperatura. Um alagamento das linhas de RPE é observado para muitas orientações a partir de -100D°C que foi interpretado como devido o congelamento da rotação dos grupos metilas, do radical no caso (II) e da matriz no caso (I) / In the present work the ESR spectra of a nitroxide radical, 4-hydroxi-2,2,6,6-tetramethylpiperidine-l-oxyl (TANOL, lI), introduced as impurity in a diamagnetic host, 4-hydroxi-2, 2,6,6-tetramethylpiperidine (1), of know structure, has been investigated. The use of the deuterated radical, 4-hydroxi-2,2, 6,6-tetramethylpiperidine-d17-1-oxyl (PD-TANOL, 111) showed an improved resolution in the ESR spectra for most orientations of the magnetic field. The interactions of protons in the neighbourhood of the paramagnetic group N-O were studied and the superhyperfine tensors for the two strongly compled protons were determined one of these protons is hydrogen bonded to the N-O and the distance is estimated to be 2,09ª°. The superhyperfine tensor has principal values -5.2; +5.4; -5.1 gauss. The second proton is further away from the electron and probably is not hydrogen bonded. The principal values for this proton are 2.0; -1.7 and -2,7 gauss. In order to study the involvment of the protons in the electronic relaxation of the radicaIs, the relaxation times T1 and T2 were estimated in the temperature range -160°C 25°C for many orientations and comparing data for the protonated and deuterated radicaIs II and III, using the continuous wave saturation method. It is shown that the relaxation time T2 is practically constant in the temperature range studied and that it is sistematically greater for the deuterated radical implying narrower lines. The spin-lattice relaxation time TI is dependent upon the orientation of the magnetic field for both radicaIs. In general a linear temperature dependence of T1-1 versus T is obtained and a mechanism of tunelling of protons between close potential walls in used to explain this behavior. In the case of the protonated radical for many orientations of the magnetic field a break is observed in the T1-1 versus T curve around -60°C for the deuterated radical this is observed only for fewer orientations. This behaviour could be explained as due to the freezing of hydrogen bonds vibration near this temperature. For many orientations it is also observed that below -100°C a broadening of the ESR lines occurs which is probably re1ated to the freezing of the rotations of the methyl groups of the radical, in the case of II, and of the hast I in the case of radical III
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Síntese, caracterização e avaliação da atividade antimicrobiana de uma hidrazona e seus complexos metálicos / Synthesis, characterization and evaluation of the antimicrobial activity of a hydrazone and its metallic complexesReis, Jéssika Vieira dos 24 July 2018 (has links)
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Previous issue date: 2018-07-24 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / With the increasing resistance of microrganisms to available drugs, mainly in hospital
environments, the pharmaceutical industries have concentrated efforts in the research of new
versatility of their molecular structures and their biological effects achieved. The hydrazones
belong to an important class as they present a broad pharmacological profile whose properties have
been extensively studied in medicinal chemistry because of their chelating capacity and the role of
coordination in their biochemical mechanism of action. In this work a chemical ligand called J3
was synthesized which was complexed with copper nitrate (II), nickel nitrate, cadmium nitrate,
cobalt perchlorate and diphenyltin dichloride, being called: J3Cu, J3Ni, J3Cd, J3Co and J3Sn,
respectively. From the formation of the crystals, they were subjected to spectroscopic analysis of
single crystal X-ray diffraction and infrared spectroscopy, which confirmed the chemical structures
obtained from the ligand and its complexes. The biological activity of the six synthesized
compounds was evaluated through the microdilution method on 96 wells plates, and the
determination of the minimum inhibitory concentration (MIC) was determined by the density
measurement in ELISA reader after incubations of 24, 48, 72 and 96 hours in bacteria of the
species Escherichia coli and Staphylococcus aureus. The J3Cu, J3Cd and J3Sn compounds
presented moderate activity for the tested bacteria, whereas the J3 ligand and its J3Co and J3Ni
complexes did not inhibit 100% of the microrganisms in the tested concentrations. Through the
tests of determination of the minimum bactericidal concentration (MBC), it was concluded that the
complexes J3Sn and J3Cd presented bacteriostatic and bactericidal activity and J3Cu complex
presented activity bacteriostatic. / Com o crescente aumento da resistência de microrganismos aos fármacos disponíveis,
principalmente em ambiente hospitalar, as indústrias farmacêuticas têm concentrado esforços
na pesquisa de novos fármacos. Diversas classes de compostos orgânicos despertam o
interesse de pesquisadores devido à versatilidade de suas estruturas moleculares e seus
efeitos biológicos alcançados. As hidrazonas pertencem a uma classe importante pois
apresentam um amplo perfil farmacológico cujas propriedades têm sido extensivamente
estudadas na Química Medicinal em razão de sua capacidade quelante e do papel da
coordenação no seu mecanismo bioquímico de ação. Neste trabalho foi sintetizado um ligante
químico denominado J3 o qual foi complexado com Nitrato de Cobre (II), Nitrato de Níquel,
Nitrato de Cádmio, Perclorato de Cobalto e Dicloreto de difenilestanho, sendo denominados
de: J3Cu, J3Ni, J3Cd, J3Co e J3Sn, respectivamente. A partir da formação dos cristais, os
mesmos foram submetidos a análises espectroscópicas de difração de raios x em monocristal
e espectroscopia na região do infravermelho, que confirmaram as estruturas químicas obtidas
do ligante e seus complexos. Foi avaliada a atividade biológica dos seis compostos
sintetizados através do método de microdiluição em placas de 96 poços, e a determinação da
concentração inibitória mínima (CIM) foi determinada através da medida de densidade em
leitor de ELISA após incubações de 24, 48, 72 e 96 horas em bactérias das espécies
Escherichia coli e Staphylococcus aureus. Foi determinada a concentração bactericida mínima
para os compostos que apresentaram CIM contra as bactérias testadas. Os compostos J3Cu,
J3Cd e J3Sn apresentaram atividade moderada para as bactérias testadas, ao passo que o
ligante J3 e seus complexos J3Co e J3Ni não inibiram 100% dos microrganismos nas
concentrações testadas. Através dos testes de determinação da concentração bactericida
mínima, concluiu-se que os complexos J3Sn e J3Cd apresentaram atividade bacteriostática e
bactericida, o complexo J3Cu apresentou atividade bacteriostática.
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Modélisation numérique de la propagation et de la bifurcation des fissures dans les superalliages monocristallins à base de nickel / Modelling the propagation and bifurcation of plasticity induced cracks in Nickel base single crystal superalloysSabnis, Prajwal 16 November 2012 (has links)
Le but principal de cette thèse est de développer un modèle numérique pour modéliser les phénomènesde bifurcation et du branchement des fissures. Pour réaliser cet objectif, il était indispensablede posséder un modèle permettant un couplage fort entre le modèle de Plasticité cristalline etcelui de l'Endommagement régularisé. Dans un premier temps, quelques outils de post-traitement ont été développés pour analyser les systèmes de glissement actifs. Ces outils ont été utilisés surdes simulations d'éprouvettes réelles, et comparés à des résultats expérimentaux. Par ces comparaisons, l'application du modèle de Plasticité cristalline aux superalliages monocristallins a été validée. Ce modèle a ensuite été couplé avec le modèle d'endommagement régularisé. Le couplage a été réalisé dans les deux sens, c'est-à-dire que l'évolution de la plasticité a une influence sur l'endommagement et vice-versa. Le nouveau modèle peut être implémenté simplement, avec la méthode traditionnelle des Éléments Finis. Des expériences étudiant la propagation de fissure sous des chargements de types différents ont été simulées à l'aide de ce nouveau modèle :éprouvettes CT,fissuration en Mode II et rupture en fluage. Une méthode pour l'identification des paramètres matériaux a également été proposée. / The main goal of this dissertation was to develop a model to simulate the processes of crack bifurcation and crack branching in anisotropic materials. To achieve this goal, a thorough coupling of crystal plasticity and regularised damage models was deemed necessary. Firstly, post-processing tools were developed to better analyse the results obtained from standard Crystal Plasticity simulations. These were then compared with experiments, thereby validating the use of Crystal Plasticity models for Nickel base single crystal superalloys. The validated Crystalplasticity model was then coupled with a regularised microdamage model such that the evolution of plasticity influenced damage and vice versa. The newly developed model allows for the simulation of cracks using the standard Finite Element Approach. Experiments studying crack propagation under different types of loads were simulated using the newly developed model, including CT, shear andcreep specimens. A methodology was also proposed for the identification of the newly introduced material parameters.
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Modélisation de la fragilisation due au gonflement dans les aciers inoxydables austénitiques irradiés / Modeling of cavity swelling-induced embrittlement in irradiated austenitic stainless steelsHan, Xu 14 December 2012 (has links)
Au cours d'une irradiation neutronique à long-terme dans les Réacteurs à Eau Pressurisée (REPs), une modification importante du comportement mécanique des matériaux utilisés dans les internes de cuve (composés des aciers inoxydables austénitiques de la série 300) est observée, y compris un durcissement et un adoucissement induit par irradiation, une perte de la ductilité et de la ténacité. Jusqu'à présent, beaucoup efforts ont été contribués pour identifier les effets d'irradiation sur l'évolution microstructurale du matériau (dislocations, boucles de Frank, cavités, ségrégation, etc.). Le gonflement induit par irradiation, considéré comme un facteur limitant la durée de fonctionnement des réacteurs, pourrait modifier les propriétés mécaniques des matériaux (plasticité, ténacité, etc), même conduire à une distorsion des structures du fait des modifications dimensionnelles entre les différentes composantes.L'objectif principal de ce travail de thèse est d'étudier qualitativement l'influence de l'effet du gonflement sur le comportement mécanique des matériaux irradiés. Un modèle micromécanique constitutif en grandes déformations basé sur les évolutions de la densité de dislocations et de défauts d'irradiation (boucles de Frank) est développé et implémenté dans les codes de calcul éléments finis ZéBuLoN et Cast3M. Les simulations numériques sont réalisées pour calculer les propriétés mécaniques d'un agrégat polycristallin. Par ailleurs, la technique d'homogénéisation est appliquée pour développer un modèle de type Gurson. Les simulations d'une cellule poreuse sont utilisés pour étudier le comportement mécanique des monocristaux poreux, en tenant compte des différents effets de la triaxialité, de la porosité et de l'orientation cristallographique, afin d'étudier l'effet de la présence des cavités sur la plasticité et la rugosité du matériau irradié à l'échelle polycristallin. / During long-time neutron irradiation occurred in Pressurized Water Reactors (PWRs), significant changes of the mechanical behavior of materials used in reactor core internals (made of 300 series austenitic stainless steels) are observed, including irradiation-induced hardening and softening, loss of ductility and toughness. So far, much effect has been made to identify radiation effects on material microstructure evolution (dislocations, Frank loops, cavities, segregation, etc.). The irradiation-induced cavity swelling, considered as a potential factor limiting the reactor lifetime, could change the mechanical properties of materials (plasticity, toughness, etc.), even lead to a structure distortion because of the dimensional modifications between different components.The principal aim of the present PhD work is to study qualitatively the influence of cavity swelling on the mechanical behaviors of irradiated materials. A micromechanical constitutive model based on dislocation and irradiation defect (Frank loops) density evolution has been developed and implemented into ZéBuLoN and Cast3M finite element codes to adapt the large deformation framework. 3D FE analysis is performed to compute the mechanical properties of a polycrystalline aggregate. Furthermore, homogenization technique is applied to develop a Gurson-type model. Unit cell simulations are used to study the mechanical behavior of porous single crystals, by accounting for various effects of stress triaxiality, of void volume fraction and of crystallographic orientation, in order to study void effect on the irradiated material plasticity and roughness at polycrystalline scale.
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Extending the Search Space for Novel Physical Forms of Pharmaceuticals and Biomolecules using High-Pressure TechniquesSaouane, Sofiane 30 September 2015 (has links)
No description available.
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Études des solutions solides de type M(1-x)M'xXO4 homéotypes du quartz-alpha et cristallogenèse d’un matériau bi-fonctionnel GaAsO4 à propriétés piézoélectriques et optiques non linéaires / Studies of M(1-x)M'xXO4 solid solutions homeotypes of alpha-quartz and crystal growth of GaAsO4,a bifunctional material with piezoelectric and nonlinear optics propertiesSouleiman, Manhal 29 November 2013 (has links)
Des cristaux de Ga1-xFexPO4 ont été obtenus par voie hydrothermale avec xmax=0.23. La synthèse hydrothermale in-situ par spectroscopie d'absorption des rayons X a permis de mettre en évidence le rôle essentiel des cations Ga3+ lors de la nucléation et la cristallisation de la phase mixte Ga1-xFexPO4 de structure quartz-α. La solution solide a été particulièrement étudiée par spectroscopie Raman et des calculs théoriques par DFT ont permis d'identifier clairement les modes de vibration dont la fréquence dépend de la composition chimique du matériau (modes couplés). Dans la même famille des matériaux de type MIIIXVO4, la cristallogénèse de monocristaux de GaAsO4 de grande taille (plusieurs cm3) a été réalisée par croissance hydrothermale basse pression (P < 2MPa). A partir de ces cristaux des mesures piézoélectriques sur résonateur ont permis de confirmer que GaAsO4, possède le coefficient de couplage électromécanique le plus élevé de la famille (20%) ce qui représente 2.5 fois les propriétés du quartz. Par ailleurs GaAsO4 possède des propriétés intéressantes dans le domaine de l'optique non-linéaire. Les mesures ont permis d'obtenir un coefficient de couplage électro-optique d11= 2.98pm/V (3.29pm/V par calcul DFT) ce qui place GaAsO4 parmi les matériaux les plus performants dans ce domaine. Compte tenu de sa haute stabilité thermique, GaAsO4 constitue un matériau bi-fonctionnel très prometteur pour des applications high-tech. / Ga1-xFexPO4 single crystals were grown by hydrothermal methods. In-situ absorption X-ray spectroscopy was used to show the essential role of solvated Ga3+ ions during the nucleation and the crystallization of the alpha-quartz type structure. Solid solutions have been investigated by Raman spectroscopy coupled with theoretical DFT calculations. The dependence of vibrational mode frequencies on the chemical composition was studied thereby allowing a linear dependence of PO4 modes frequencies with the iron content (xFe) to be identified. In the second part, crystal growth of large single crystals (several cm3) of GaAsO4 was performed. The piezoelectric coupling coefficient of 20% was measured, which is 2.5 times that of alpha-quartz. Non-linear optical properties were also measured: the electro-optical coupling coefficient d11 is 2.98pm/V (3.29pm/V with DFT calculations). Due to the high thermal stability, GaAsO4 is a very promising bifunctional material for high technology applications.
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