O objetivo deste estudo in vitro foi avaliar e comparar a microestrutura e a composição mineral do esmalte e da dentina de dentes decíduos e permanentes. Terceiros molares hígidos e segundos molares decíduos foram selecionados e distribuídos aleatoriamente em grupos, de acordo com o método de análise dos substratos utilizado: Microscopia Eletrônica de Varredura (MEV), Espectroscopia de Energia Dispersiva de Raio X (EDX), Difração de Raio X (DRX) e Microscopia Óptica (MO). Foi realizada comparação qualitativa e quantitativa da estrutura dental. As medidas de densidade numérica e diâmetro dos prismas de esmalte/túbulos dentinários e, de espessura do esmalte, dentina e dentina peritubular foram realizadas por meio de fotomicrografias obtidas pela MEV. Os resultados obtidos por meio da SEM foram analisados estatisticamente pelo teste não-paramétrico de Kruskal-Wallis. A quantidade relativa de íons cálcio (Ca) e fósforo (P) foram determinadas por meio de EDX e as fases químicas presentes em ambos os substratos, por análise de DRX. O valor das medidas de espessura observado para o esmalte e dentina dos dentes decíduos foi de 1.14 mm e 3.02 mm, respectivamente. Para os dentes permanentes, obtiveram-se valores de 2.58 mm para o esmalte e 5.95 mm para a dentina. Com relação ao diâmetro da cabeça dos prismas de esmalte, os resultados foram estatisticamente semelhantes para os dentes decíduos e permanentes, demonstrando uma ligeira diminuição do diâmetro da superfície externa para a região próxima a junção amelodentinária (JAD). A densidade numérica dos prismas foi maior nos dentes decíduos, principalmente próximo à JAD, sendo estatisticamente diferente dos valores observados nos dentes permanentes, independente da região analisada. Na análise do diâmetro e densidade numérica dos túbulos dentinários verificou-se semelhança estatística entre os dentes decíduos e permanentes, havendo aumento gradativo do número de túbulos a partir da JAD em direção a região próxima a polpa. A espessura da dentina peritubular, na região próxima a JAD e central foi, respectivamente, 0.91 e 0.59 mm nos dentes decíduos 1.16 e 0.98 mm nos dentes permanentes. A porcentagem de Ca e P foi maior nos dentes permanentes. Observou-se ainda, que a quantidade de colágeno nos dentes decíduos foi aparentemente menor quando analisados por meio da MO. De acordo com os resultados obtidos neste estudo, pode-se concluir que, de maneira geral, os dentes decíduos apresentam menor porcentagem de Ca e P, menor espessura de esmalte e dentina, maior densidade numérica de prismas e dentina peritubular mais delgada quando comparada aos dentes permanentes. / This study evaluated in vitro the microstructure and mineral composition of dental enamel and dentin comparing the permanent teeth with the deciduous teeth. Sound third molars and second primary molars were selected and randomly assigned to the following groups, according to the analysis methods of the substrates performed: Scanning Electron Microscopy (SEM), X-Ray diffraction (XRD), Energy dispersive X-ray spectrometer (EDS) and Optical Microscopy (OP). A qualitative and quantitative comparison of the dental structure was done. The measurements of the number and diameter of prisms/tubules, thickness of enamel, dentin and peritubular dentin were done in SEM photomicrographs. The microscopic findings were analyzed statistically by a non-parametric test (Kruskal- Wallis). The relative amounts of calcium (Ca) and phosphorus (P) were determined by EDS investigation. Phase present in both types of teeth were observed by the XRD analysis. The mean thickness measurements observed in the deciduous teeth enamel and dentin was, respectively, 1.14 mm and 3.02 mm and in the permanent teeth, 2.58 mm and 5.95 mm. The mean rod head diameter in deciduous teeth was statistically similar to that of permanent teeth enamel, and a slightly decrease from the outer enamel surface to the region next to the enameldentine junction was assessed. The numerical density of enamel rods was higher in the deciduous teeth, mainly near EDJ, that showed statistically significant difference. The mean tubules number and diameter in deciduous teeth were statistically similar to that of permanent teeth, and this numerical density increased from the EDJ to the region near the pulp. The mean thickness measurements of peritubular dentin observed in the regions near EDJ and central were, respectively, 0.91 and 0.59 mm for the primary teeth / 1.16 and 0.98 mm for the permanent teeth. The percentage of Ca and P was higher in the permanent teeth. The collagen level was apparently lower in deciduous teeth when analyzed by OP. The primary teeth structure showed a lower level of Ca and P and a thinner enamel and dentin thickness. The deciduous enamel presented higher numerical density of rods. The peritubular dentin was thicker in the permanent teeth.

Este trabalho foi desenvolvido objetivando a determinação e a avaliação dos perfis temporais da concentração de alguns elementos químicos potencialmente tóxicos presentes no material particulado em suspensão (MPS) no interior de uma pequena indústria de fundição de metais bronze, ferro e alumínio que, em concentrações elevadas, podem acarretar sérios riscos à saúde do trabalhador. Para isso foi utilizado um amostrador temporal de MPS, que coleta amostras de aerossóis em intervalo de tempo pré-programados, separando-os por tamanho: (a) fração fina ou respirável (partículas com diâmetro aerodinâmico menor que 2,5 m, MP2,5) e (b) fração grossa ou inalável (entre 2,5 a 10 m, MP10-2,5), durante todo o período do processo de fundição (da fusão à moldagem). As amostras coletadas, na forma de faixas (strips) sobre um filtro (fração fina) e sobre um impactador (fração grossa), foram analisadas pela técnica de fluorescência de raios X por dispersão de energia (EDXRF), utilizando na excitação um tubo de raios X com alvo de Mo e e na detecção dos raios X característicos um detector semicondutor de Si(Li) acoplado a um analisador de pulsos multicanal, interpretando-se posteriormente os espectros de raios X obtidos pelo aplicativo AXIL. Para algumas amostras também foi feita uma análise com microscópio eletrônico de varredura (SEM/EDS) para se conhecer a morfologia dos particulados. Deste modo foi possível determinar a concentração de elementos químicos potencialmente tóxicos presentes em um ambiente de uma pequena indústria de fundição de metais, mostrando que o momento mais crítico dessa atividade foi o da moldagem e também determinar a forma do MPS. Na fundição do bronze e ferro, as concentrações dos elementos Cr, Mn, Ni e Pb, principalmente na fração fina no momento de moldagem, mostraram-se muito superior aos limites recomendados pelas agências brasileira e norte-americana. Apesar de não haver limites recomendados para o elemento Zn, foi verificada uma alta concentração principalmente na concentração na fração fina, o mesmo sucedendo para o Cu. Com respeito a fundição de alumínio, foi observado altas concentrações principalmente de Zn e Cu, somente na fração fina, não ocorrendo na fração grossa. Pelos resultados obtidos pode-se concluir que os trabalhadores estão sujeitos a condições insalubres de trabalho nesse tipo de ambiente, aconselhando-se o uso permanente de equipamentos adequados de proteção visando de preferência a fração fina, assim como um monitoramento constante desses elementos químicos durante todas as etapas do processo de fundição, principalmente na de moldagem / The aim of this work was to evaluate the chemical concentration of some potentially toxic inorganic chemical elements and the time profiles in fine (PM2.5, particles up to 2.5 m) and coarse (PM2.5-10, particles from 2.5 to 10 m) suspended particulate matter (SPM) inside a small foundry plant - bronze, iron and aluminium -, in which at high concentrations turns a healthy concern. For these purpose, a rotating streaker airparticulate sampler for sampling during all day foundry activity was utilized. Fine SPM was collected on a filter and coarse SPM in turn by an impactor. The collected samples were analyzed by energy dispersive X-ray fluorescence (EDXRF) technique employing a Mo target tube in the excitation, and the detection was carried out through Si(Li) semiconductor detector coupled to multichannel analyser, deconvolutting the X-ray spectra with AXIL software help. It was also carried out particulated morphological analysis by scanning electron microscopy with energy dispersive X-ray spectrometer coupled (SEM/EDS). In this manner, the inorganic chemicals content were determined in the small foundry allowing concluding that the moulding step is the critical one taking into account the amount of pollutant released. During bronze and iron melting, the Cr, Mn, Ni and Pb contents in SPM were higher than allowed values by Brazilian and United States legislations. It was also verified a high Zn and Cu content, mainly in the fine suspended particulate matter, although these elements are not contemplated by national nor international laws. Thus, due to this unhealthy environmental working conditions inside the small foundry plant,a proper individual protection equipment is mandatory mainly for fine suspended particulate matter, and a constant air pollutant monitoring in foundry plants is demanded, mainly during the moulding step

O Brasil produz cerca de 2,2 milhões de metros cúbicos de madeira preservada para atender à demanda anual nos setores de transporte ferroviário, elétrico, rural e de construção civil. As espécies de madeiras mais usados são do eucalipto (Eucalyptus sp.) e pinus (Pinus sp.). A madeira preservada, utilizada para postes, dormentes, mourões e nas construções em madeira, deve estar em conformidade com as especificações exigidas pelas normas brasileiras quanto ao seu tratamento preservativo. No Brasil, os preservativos de madeira mais utilizados e regulamentados são CCA (arseniato de cobre cromatado) e o CCB (sal de cobre cromo e boro). As técnicas analíticas como espectrometria de absorção atómica de chama (FAAS) e espectrometria de emissão de plasma acoplado (ICPOES) e espectrometria de fluorescência de raios x (XRFS) são utilizadas para a avaliação desses processos. Neste trabalho, as amostras de madeira foram obtidas de árvores de eucalipto (Eucalyptus sp.), provenientes de áreas de plantação do estado de Minas Gerais, Brasil. Amostras de madeira de eucalipto foram submetidas a diferentes concentrações de solução de CCA, sob pressão, atingindo retenções de 3,9; 6,7; 9,1; 12,4 e 14,0 kg de CCA por m-³ de alburno. A partir dos blocos tratados foram obtidos amostras em forma de cilindros e serragem. A determinação de cobre, cromo e arsênio foi realizada pela espectrometria de fluorescência de raios X de energia dispersiva (EDXRF), espectrometria de fluorescência de raios X portátil (PXRF), FAAS e IAAN. Neste trabalho, foram avaliados métodos de análise, sensibilidade e precisão, exatidão das técnicas analíticas relacionadas. / Brazil produces around 2.2 millions of cubic meters of treated wood to meet the annual demand of railway, electric, rural and construction sectors. The most used wood species are eucalyptus (Eucalyptus ssp.) and pine (Pinus ssp.).The treated woods used for poles, sleepers, fence posts and plywoods should be according to Brazilian norms requirements. The most usual wood preservative products used in Brazil are CCA (chromated copper arsenate) and CCB (copper chromium and boron salt). The analytical methods, such as flame atomic absorption spectrometry (FAAS), plasma inductively coupled optical emission spectrometry (ICPOES) and X-ray fluorescence spectrometry (XRFS) have been used for the analytical control of those treatment processes. In this work, the eucalyptus trees (Eucalyptus ssp) samples was obtained from Minas Gerais State, Brazil, cut plantation areas. Under pressure, eucalyptus wood samples were submitted to different concentration of CCA solution reaching 3.9, 6.7, 9.1, 12.4 and 14.0 kg of CCA by m-³ sapwood retentions. Samples in cylinders and sawdust forms were obtained from treated wood samples. Copper, chromium and arsenic determination was performed using the energy dispersive X-ray fluorescence spectrometry (EDXRFS), portable X-ray fluorescence spectrometry (PXRFS), flame atomic absorption spectrometry (FAAS) and instrumental neutron activation analysis. In this work, the method of analysis, sensitivity, precision and accuracy performances of the related techniques were outlined.

O Brasil produz cerca de 2,2 milhões de metros cúbicos de madeira preservada para atender à demanda anual nos setores de transporte ferroviário, elétrico, rural e de construção civil. As espécies de madeiras mais usados são do eucalipto (Eucalyptus sp.) e pinus (Pinus sp.). A madeira preservada, utilizada para postes, dormentes, mourões e nas construções em madeira, deve estar em conformidade com as especificações exigidas pelas normas brasileiras quanto ao seu tratamento preservativo. No Brasil, os preservativos de madeira mais utilizados e regulamentados são CCA (arseniato de cobre cromatado) e o CCB (sal de cobre cromo e boro). As técnicas analíticas como espectrometria de absorção atómica de chama (FAAS) e espectrometria de emissão de plasma acoplado (ICPOES) e espectrometria de fluorescência de raios x (XRFS) são utilizadas para a avaliação desses processos. Neste trabalho, as amostras de madeira foram obtidas de árvores de eucalipto (Eucalyptus sp.), provenientes de áreas de plantação do estado de Minas Gerais, Brasil. Amostras de madeira de eucalipto foram submetidas a diferentes concentrações de solução de CCA, sob pressão, atingindo retenções de 3,9; 6,7; 9,1; 12,4 e 14,0 kg de CCA por m-³ de alburno. A partir dos blocos tratados foram obtidos amostras em forma de cilindros e serragem. A determinação de cobre, cromo e arsênio foi realizada pela espectrometria de fluorescência de raios X de energia dispersiva (EDXRF), espectrometria de fluorescência de raios X portátil (PXRF), FAAS e IAAN. Neste trabalho, foram avaliados métodos de análise, sensibilidade e precisão, exatidão das técnicas analíticas relacionadas. / Brazil produces around 2.2 millions of cubic meters of treated wood to meet the annual demand of railway, electric, rural and construction sectors. The most used wood species are eucalyptus (Eucalyptus ssp.) and pine (Pinus ssp.).The treated woods used for poles, sleepers, fence posts and plywoods should be according to Brazilian norms requirements. The most usual wood preservative products used in Brazil are CCA (chromated copper arsenate) and CCB (copper chromium and boron salt). The analytical methods, such as flame atomic absorption spectrometry (FAAS), plasma inductively coupled optical emission spectrometry (ICPOES) and X-ray fluorescence spectrometry (XRFS) have been used for the analytical control of those treatment processes. In this work, the eucalyptus trees (Eucalyptus ssp) samples was obtained from Minas Gerais State, Brazil, cut plantation areas. Under pressure, eucalyptus wood samples were submitted to different concentration of CCA solution reaching 3.9, 6.7, 9.1, 12.4 and 14.0 kg of CCA by m-³ sapwood retentions. Samples in cylinders and sawdust forms were obtained from treated wood samples. Copper, chromium and arsenic determination was performed using the energy dispersive X-ray fluorescence spectrometry (EDXRFS), portable X-ray fluorescence spectrometry (PXRFS), flame atomic absorption spectrometry (FAAS) and instrumental neutron activation analysis. In this work, the method of analysis, sensitivity, precision and accuracy performances of the related techniques were outlined.

Plugged and abandoned well pads throughout the Uintah Basin face reclamation challenges due to factors including a harsh climate, invasive species, and high salt loads. Finding ways to alleviate soil sodicity could improve soil reclamation success. Gypsum, sulfur, activated carbon, and Biochar are being applied to improve soil parameters negatively impacted by sodicity, but the direct impact of these amendments on Uintah Basin soils is still largely unknown. The aim of this study was two-fold. (1) Evaluate the effectiveness of gypsum, sulfuric acid, Biochar, activated carbon, and combinations of these amendments in reducing the impact of soil sodicity of the Desilt and Conglomerate soils by measuring amendment impact on percent dispersion, saturated hydraulic conductivity, crust bulk density, infiltration, and crust formation. (2) Compare a crust bulk density method using ImageJ to the clod wax density method and a modified linear extensibility percent equation to the linear extensibility percent equation to assess whether the novel methods can be used to accurately measure and calculate soil crust bulk density and shrink swell potential while reducing human error and analysis time.

For the automotive sector, plastics play the most important role when designing interior and exterior parts for cars. Currently, most parts are made from petroleum-based plastics but alternatives are needed to replace environmentally harmful materials while providing the appropriate mechanical performance and preferably reduce the cost for the final product. The objective of this work was to explore the use of soy flakes as natural filler in a composite with polypropylene and to investigate the mechanical properties, water absorption and thermal behaviour. For a better understanding of the filler, the soy flakes were characterized extensively with analytical and microscopic methods. Two types of soy fillers were investigated, soy flakes, provided by Bunge Inc., with a 48 wt-% protein content and an industrial soy based filler with 44 wt-% protein content and provided by Ford. The size of the soy flakes after milling was mainly between 50 and 200 µm and below 50 µm for the industrial filler. The aspect ratio for all filler was below 5. The soy flakes were used after milling and subjected to two pre-treatment methods: (1) one hour in a 50 °C pH 9 water solution in a 1 : 9 solid-liquid ratio; (2) one hour in a 50 °C pH 9 1M NaCl solution in a 1 : 9 solid-liquid ratio. A control filler, without pre-treatment was considered. The soy flakes were also compared to an industrial soy based filler provided by Ford (soy flour (Ford)). The thermogravimetric analysis showed an onset of degradation at 170 °C for the treated filler (ISH2O and ISNaCl) and 160 °C for the untreated filler. The biocomposites formulation consisted of 30 wt-% filler, and polypropylene with/without 0.35 wt-% anti-oxidant Irganox 1010 and with/without the addition of MA-PP as coupling agent. All biocomposites were compounded in a mini-extruder, pressed into bars by injection moulding and tested subsequently. The mechanical properties of the biocomposites are promising. An increase of the E-modulus was observed when compared to pure polypropylene. The addition of MA-PP as coupling agent increased the yield strength of the biocomposites. When pure polypropylene and the biocomposites were compared no difference could be seen for their yield strength. The thermal behaviour deduced from differential scanning calorimetry, revealed a similar behaviour for the biocomposites and the pure polypropylene. Only the samples treated in the presence of NaCl and without a coupling agent, appear to have a slightly higher degree of crystallinity. The melt flow index was slightly increased for the biocomposites containing soy flakes pre-treated with NaCl and decreased for biocomposites containing the soy flour. The water absorption behaviour of the biocomposites was quite similar at the beginning with a slightly lower absorption for the materials with coupling agent. After three months, all samples except the ones treated with water showed a weight loss that can be due to the leaching of the water soluble components in the untreated filler and the NaCl treated filler. In conclusion, soy flakes represent an attractive filler when used in a polypropylene matrix if an aqueous alkaline pre-treatment is performed. The aqueous alkaline extraction also leads to the recovery of the proteins that can be used in food products while the remaining insoluble material is used for the biocomposites, avoiding the competition with the use of soy for food products...

For the automotive sector, plastics play the most important role when designing interior and exterior parts for cars. Currently, most parts are made from petroleum-based plastics but alternatives are needed to replace environmentally harmful materials while providing the appropriate mechanical performance and preferably reduce the cost for the final product. The objective of this work was to explore the use of soy flakes as natural filler in a composite with polypropylene and to investigate the mechanical properties, water absorption and thermal behaviour. For a better understanding of the filler, the soy flakes were characterized extensively with analytical and microscopic methods. Two types of soy fillers were investigated, soy flakes, provided by Bunge Inc., with a 48 wt-% protein content and an industrial soy based filler with 44 wt-% protein content and provided by Ford. The size of the soy flakes after milling was mainly between 50 and 200 µm and below 50 µm for the industrial filler. The aspect ratio for all filler was below 5. The soy flakes were used after milling and subjected to two pre-treatment methods: (1) one hour in a 50 °C pH 9 water solution in a 1 : 9 solid-liquid ratio; (2) one hour in a 50 °C pH 9 1M NaCl solution in a 1 : 9 solid-liquid ratio. A control filler, without pre-treatment was considered. The soy flakes were also compared to an industrial soy based filler provided by Ford (soy flour (Ford)). The thermogravimetric analysis showed an onset of degradation at 170 °C for the treated filler (ISH2O and ISNaCl) and 160 °C for the untreated filler. The biocomposites formulation consisted of 30 wt-% filler, and polypropylene with/without 0.35 wt-% anti-oxidant Irganox 1010 and with/without the addition of MA-PP as coupling agent. All biocomposites were compounded in a mini-extruder, pressed into bars by injection moulding and tested subsequently. The mechanical properties of the biocomposites are promising. An increase of the E-modulus was observed when compared to pure polypropylene. The addition of MA-PP as coupling agent increased the yield strength of the biocomposites. When pure polypropylene and the biocomposites were compared no difference could be seen for their yield strength. The thermal behaviour deduced from differential scanning calorimetry, revealed a similar behaviour for the biocomposites and the pure polypropylene. Only the samples treated in the presence of NaCl and without a coupling agent, appear to have a slightly higher degree of crystallinity. The melt flow index was slightly increased for the biocomposites containing soy flakes pre-treated with NaCl and decreased for biocomposites containing the soy flour. The water absorption behaviour of the biocomposites was quite similar at the beginning with a slightly lower absorption for the materials with coupling agent. After three months, all samples except the ones treated with water showed a weight loss that can be due to the leaching of the water soluble components in the untreated filler and the NaCl treated filler. In conclusion, soy flakes represent an attractive filler when used in a polypropylene matrix if an aqueous alkaline pre-treatment is performed. The aqueous alkaline extraction also leads to the recovery of the proteins that can be used in food products while the remaining insoluble material is used for the biocomposites, avoiding the competition with the use of soy for food products...

Thermo-stabilized lignin fibers from pH-fractionated softwood kraft lignin were carbonized to various temperatures during thermomechanical analysis (TMA) under static and increasing load and different rates of heating. The aim was to optimize the carbonization process to obtain suitable carbon fiber material with good mechanical strength potential (high tensile strength and high E-modulus). The carbon fibers were therefore mainly evaluated of mechanical strength in Dia-Stron uniaxial tensile testing. In addition, chemical composition, in terms of functional groups, and elemental (atomic) composition was studied in Fourier transform infrared spectroscopy (FTIR) and in energy-dispersive X-ray spectroscopy (EDS), respectively. The structure of carbon fibers was imaged in scanning electron microscope (SEM) and light microscopy. Thermogravimetrical analysis was performed on thermo-stabilized lignin fibers to evaluate the loss of mass and to calculate the stress-changes and diameter-changes that occur during carbonization. The TMA-analysis of the deformation showed, for thermo-stabilized lignin fibers, a characteristic behavior of contraction during carbonization. Carbonization temperatures above 1000°C seemed most efficient in terms of E-modulus and tensile strength whereas rate of heating did not matter considerably. The E-modulus for the fibers was improved significantly by slowly increasing the load during the carbonization. The tensile strength remained however unchanged. The FTIR-analysis indicated that many functional groups, mainly oxygen containing, dissociate from the lignin polymers during carbonization. The EDS supported this by showing that the oxygen content decreased. Accordingly, the relative carbon content increased passively to around 90% at 1000°C. Aromatic structures in the carbon fibers are thought to contribute to the mechanical strength and are likely formed during the carbonization. However, the FTIR result showed no evident signs that aromatic structures had been formed, possible due to some difficulties with the KBr-method. In the SEM and light microscopy imaging one could observe that porous formations on the surface of the fibers increased as the temperature increased in the carbonization. These formations may have affected the mechanical strength of the carbon fibers, mainly tensile strength. The carbonization process was optimized in the sense that any heating rate can be used. No restriction in production speed exists. The carbonization should be run to at least 1000°C to achieve maximum mechanical strength, both in E-modulus and tensile strength. To improve the E-modulus further, a slowly increasing load can be applied to the lignin fibers during carbonization. The earlier the force is applied, to counteract the lignin fiber contraction that occurs (namely around 300°C), the better. However, in terms of mechanical performance, the lignin carbon fibers are still far from practical use in the industry.

Dans ce travail de thèse a été développé et étudié un nouveau type d'objet semiconducteur magnétique : des boîtes quantiques de CdMnTe insérées dans des nanofils de ZnTe/ZnMgTe constituant une structure de type cœur-coquille. L'objectif était d'étudier la croissance par épitaxie par jets moléculaires et les propriétés fondamentales de ces hétéro-structures complexes. Dans ce but deux aspects principaux ont été abordés : i) la qualité et le contrôle des propriétés structurales, électroniques et magnétiques de ces objets, grâce à une maîtrise de leur croissance et ii) l'obtention d'informations quantitatives locales sur la composition chimique de ces nanostructures inhomogènes. Pour atteindre ces objectifs, nous avons divisé notre étude en quatre étapes. La première étape de ce travail a été concentrée sur l'étude quantitative de la formation des particules d'or servant de catalyseurs à la croissance des nanofils. La seconde étape a porté sur l'analyse des mécanismes de croissance et des paramètres gouvernant la croissance des fils de ZnTe. En particulier deux types de fils ont été observés : des fils cylindriques de structure wurtzite et des fils coniques de structures zinc-blende. Un modèle de croissance guidée par la diffusion a été utilisé pour rendre compte de certains des résultats quantitatifs présentés dans cette partie. La troisième étape a concerné l'insertion de boîtes quantiques de CdMnTe dans des nanofils de structure cœur-coquille ZnTe/ZnMgTe. Une étude préalable des paramètres pertinents influençant les propriétés magnéto-optiques de ces objets, tels que le confinement de la boîte quantique, l'incorporation du Mn et l'anisotropie de contrainte créée par la structure, a été menée. La quatrième et dernière étape de ce travail a porté sur l'interprétation quantitative de mesures d'analyse dispersive en énergie effectuées sur des nanofils de structure cœur-multicoquille. Un modèle géométrique a été proposé, permettant de retrouver la forme, les dimensions et la composition chimique des boîtes quantiques et des coquilles. Cette étude a été couplée à des mesures de caractérisation telles que la cathodo-luminescence, la micro-photo-luminescence et la spectroscopie magnéto-optique effectuées sur le même nanofil. / In this PhD work a novel type of magnetic semiconductor object has been developed: Cd(Mn)Te quantum dots embedded in ZnTe/ZnMgTe core-shell nanowires. The goal was to investigate the growth, by molecular beam epitaxy, and the fundamental properties of these complex heterostructures. For that purpose, two main issues were addressed: i) gaining control of the structural, electronic and magnetic properties of these quantum objects by mastering their growth; and ii) obtaining quantitative local knowledge on the chemical composition of those non-homogeneous nanostructures. To tackle these topics, our research was divided into four stages. The first stage was devoted to perform a quantitative study of the formation process of the Au particles that catalyze the growth of nanowires. The second stage involved the analysis of the mechanisms and parameters governing the growth of ZnTe nanowires. In particular, two different types of nanowires were found: cone-shaped nanowires with the zinc-blende crystal structure and cylinder-shaped nanowires with the hexagonal wurtzite structure. A diffusion-driven growth model is employed to fit some of the quantitative results presented in this part. The third stage focused on the insertion of pure CdTe quantum dots containing Mn ions in the core-shell nanowires. An initial study of the relevant parameters influencing the magneto-optical properties of these objects, such as the quantum dot confinement, the Mn incorporation, and the strain anisotropy, was performed. The four and last stage of this work concerned the quantitative interpretation of Energy-Dispersive X-ray spectroscopy measurements performed on single core-multishell nanowires. A geometrical model was proposed to retrieve the shape, the size and the local composition of the quantum dot insertions and of the multiple layers of the heterostructures. This study was coupled to other complementary characterization measurements on the same nanowire, such as cathodo-luminescence, micro-photo-luminescence and magneto-optical spectroscopy.

Dans ce travail de thèse a été développé et étudié un nouveau type d'objet semiconducteur magnétique : des boîtes quantiques de CdMnTe insérées dans des nanofils de ZnTe/ZnMgTe constituant une structure de type cœur-coquille. L'objectif était d'étudier la croissance par épitaxie par jets moléculaires et les propriétés fondamentales de ces hétéro-structures complexes. Dans ce but deux aspects principaux ont été abordés : i) la qualité et le contrôle des propriétés structurales, électroniques et magnétiques de ces objets, grâce à une maîtrise de leur croissance et ii) l'obtention d'informations quantitatives locales sur la composition chimique de ces nanostructures inhomogènes. Pour atteindre ces objectifs, nous avons divisé notre étude en quatre étapes. La première étape de ce travail a été concentrée sur l'étude quantitative de la formation des particules d'or servant de catalyseurs à la croissance des nanofils. La seconde étape a porté sur l'analyse des mécanismes de croissance et des paramètres gouvernant la croissance des fils de ZnTe. En particulier deux types de fils ont été observés : des fils cylindriques de structure wurtzite et des fils coniques de structures zinc-blende. Un modèle de croissance guidée par la diffusion a été utilisé pour rendre compte de certains des résultats quantitatifs présentés dans cette partie. La troisième étape a concerné l'insertion de boîtes quantiques de CdMnTe dans des nanofils de structure cœur-coquille ZnTe/ZnMgTe. Une étude préalable des paramètres pertinents influençant les propriétés magnéto-optiques de ces objets, tels que le confinement de la boîte quantique, l'incorporation du Mn et l'anisotropie de contrainte créée par la structure, a été menée. La quatrième et dernière étape de ce travail a porté sur l'interprétation quantitative de mesures d'analyse dispersive en énergie effectuées sur des nanofils de structure cœur-multicoquille. Un modèle géométrique a été proposé, permettant de retrouver la forme, les dimensions et la composition chimique des boîtes quantiques et des coquilles. Cette étude a été couplée à des mesures de caractérisation telles que la cathodo-luminescence, la micro-photo-luminescence et la spectroscopie magnéto-optique effectuées sur le même nanofil. / In this PhD work a novel type of magnetic semiconductor object has been developed: Cd(Mn)Te quantum dots embedded in ZnTe/ZnMgTe core-shell nanowires. The goal was to investigate the growth, by molecular beam epitaxy, and the fundamental properties of these complex heterostructures. For that purpose, two main issues were addressed: i) gaining control of the structural, electronic and magnetic properties of these quantum objects by mastering their growth; and ii) obtaining quantitative local knowledge on the chemical composition of those non-homogeneous nanostructures. To tackle these topics, our research was divided into four stages. The first stage was devoted to perform a quantitative study of the formation process of the Au particles that catalyze the growth of nanowires. The second stage involved the analysis of the mechanisms and parameters governing the growth of ZnTe nanowires. In particular, two different types of nanowires were found: cone-shaped nanowires with the zinc-blende crystal structure and cylinder-shaped nanowires with the hexagonal wurtzite structure. A diffusion-driven growth model is employed to fit some of the quantitative results presented in this part. The third stage focused on the insertion of pure CdTe quantum dots containing Mn ions in the core-shell nanowires. An initial study of the relevant parameters influencing the magneto-optical properties of these objects, such as the quantum dot confinement, the Mn incorporation, and the strain anisotropy, was performed. The four and last stage of this work concerned the quantitative interpretation of Energy-Dispersive X-ray spectroscopy measurements performed on single core-multishell nanowires. A geometrical model was proposed to retrieve the shape, the size and the local composition of the quantum dot insertions and of the multiple layers of the heterostructures. This study was coupled to other complementary characterization measurements on the same nanowire, such as cathodo-luminescence, micro-photo-luminescence and magneto-optical spectroscopy.