Este trabalho consiste na síntese, caracterização e estudo da decomposição térmica de etanossulfonatos de terras raras, abordando aspectos relativos à etapa de desidratação e decomposição térmica dos sais anidros. As reações entre o ácido etanossulfônico e os óxidos de terras raras, em meio aquoso, permitiram obter os etanossulfonatos de terras raras, com fórmula geral mínima TR(C2H5SO3)3.xH2O, sendo TR = La ao Lu e Y, exceto o Ce, com x variando de 1,3 a 5. Esta estequiometria foi proposta a partir dos resultados de O estudo do comportamento térmico dos compostos foi realizado empregando a TG/DTG sob atmosfera dinâmica de N2 e ar, com razão de aquecimento de 5ºC.min-1 para a etapa de desidratação e 10ºC.min-1 para a etapa de decomposição térmica dos sais anidros. Os eventos térmicos foram evidenciados nas curvas DSC (etapa de desidratação) por picos no sentido endotérmico e estão em concordância com as variações de massa indicadas na TG/DTG. As curvas TG/DTG mostraram eventos sobrepostos, característicos da saída simultânea de vários voláteis durante a decomposição térmica das espécies anidras. Na etapa de desidratação, os resultados de análise térmica indicaram que ao longo da série as moléculas de água apresentam diferentes formas de ligação. A técnica de espectroscopia de absorção na região do infravermelho permitiu verificar uma grande similaridade entre os compostos e que as espécies são hidratadas. Os desdobramentos e deslocamentos de algumas bandas de absorção são indicativas da alteração na forma de interação da espécie etanossulfonato com os íons TR3+ em relação à espécie no ácido livre. A técnica de difração de raios X indicou que os compostos são cristalinos e permitiu separá-los em sete classes isomorfas. A caracterização dos produtos intermediários da decomposição térmica dos sais anidros permitiu inferir a presença de espécies sulfatos, que em alguns casos só se decompõe acima de 1300oC. / This work consists of the Synthesis, characterization and study of thermal decomposition of rare earth ethanessulfonates, involving aspects relative to the step of dehydration and thermal decomposition of the anhydrous salts. The reactions between ethanessulfonic acid and rare earth oxides, in aqueous medium, allowed to get the rare earth ethanessulfonates of, with the general formula minimum TR (C2H5SO3)3.xH2O, TR = La to Lu and Y, except Ce, with x varying 1,3 to 5. This stoichiometry was proposal from the results of elemental analysis associated to the thermogravimetry. The thermal behavior of the compounds was studied throughout the TG/DTG under dynamic N2 and air atmosphere, with heating rate of 5oC.min-1 for the dehydration stage and 10ºC.min-1 for the thermal decomposition step of the anhydrous salts. The thermal events were evidenced in DSC curves (dehydration stage) for peaks in the endothermic direction and they are in agreement with the mass loss indicated in TG/DTG curves. TG/DTG curves had, simultaneously, shown events overlapped, which are characteristic of the releasing of some volatile during the thermal decomposition of the anhydrous species. In the dehydration step, the results of the thermal analysis indicate that through the series the water molecules present different forms of bond. Infrared spectroscopy technique allowed to verify a great similarity between compounds and that the species are hydrated. The unfoldings and shifts of some absorption bands are indicative of the change in the interaction form of ethanessulfonates species with TR3+ íons in relation species in the free acid. X rays diffraction technique indicated that the compounds are crystalline and it allowed to classify in seven isomorph series. The characterization of the intermediate products of the thermal decomposition of the anhydrous salts allowed to infer the presence of sulfate species, in some cases, exactly above of the 1300oC.

Os eletrocatalisadores PtRu/C-terras raras e PtSn/C-terras raras (20% em massa) foram preparados pelo método da redução por álcool utilizando H2PtCl6.6H2O RuCl3·xH2O, SnCl2.2H2O como fonte de metais, 85 % Vulcan - 15 % de terras raras como suporte e, por último, etileno glicol como agente redutor. Os eletrocatalisadores obtidos foram caracterizados fisicamente por difração de raios-X (DRX), energia dispersiva de raios X (EDX) e microscopia eletrônica de transmissão (MET). As análises por EDX mostraram que as razões atômicas dos diferentes eletrocatalisadores, preparados pelo método da redução por álcool, são similares às composições nominais de partida indicando que esta metodologia é promissora para a preparação destes eletrocatalisadores. Em todos os difratogramas para os eletrocatalisadores preparados observa-se um pico largo em aproximadamente 2θ = 25o, o qual é associado ao suporte de carbono e quatro outros picos de difração em aproximadamente 2θ = 40o, 47o, 67o e 82o, que por sua vez são associados aos planos (111), (200), (220) e (311), respectivamente, da estrutura cúbica de face centrada (CFC) de platina. Os resultados de difração de raios X também mostraram tamanhos médios de cristalitos entre 2,0 e 4,0 nm para PtSn e 2,0 a 3,0 para PtRu. Os estudos para a oxidação eletroquímica do etanol em meio ácido foram realizados utilizando a técnica de cronoamperometria em uma solução 0,5 mol.L-1 H2SO4, + 1,0 mol.L-1 de C2H5OH. As curvas de polarização obtidas na célula a combustível unitária, alimentada diretamente por etanol, estão de acordo com os resultados de voltametria e cronoamperometria constatando o efeito benéfico das terras raras na preparação dos eletrocatalisadores e atestando que os eletrocatalisadores de PtSn/C são mais efetivos que PtRu/C para a oxidação do etanol. / The electrocatalyst PtRu / C-rare earth and PtSn / C-rare earth (20 wt%) were prepared by alcohol reduction method using H2PtCl6.6H2O RuCl3·xH2O, SnCl2.2H2O as a source of metals 85 % Vulcan - 15 % rare earth as a support and, finally, ethylene glycol as reducing agent. The electrocatalysts were characterized physically by X-ray diffraction (XRD), energy dispersive X-ray (EDX), and transmission electron microscopy (TEM). Analyses by EDX showed that the atomic ratios of different electrocatalysts, prepared by alcohol reduction method are similar to the nominal starting compositions indicating that this methodology is promising for the preparation of electrocatalysts. In all the XRD patterns for the prepared electrocatalysts there is a broad peak at about 2θ = 25o, which is associated with the carbon support and four additional diffraction peaks at approximately 2θ = 40o, 47o, 67o e 82o, which in turn are associated with the plans (111), (200), (220) e (311), respectively, of face-centered cubic structure (FCC) platinum. The results of X-ray diffraction also showed average crystallite sizes between 2.0 and 4.0 nm for PtSn e 2,0 a 3,0 para PtRu. The studies for the electrochemical oxidation of ethanol in acid medium were carried out using the technique of chronoamperometry in a solution 0,5 mol.L-1 H2SO4, + 1,0 mol.L-1 de C2H5OH. The polarization curves obtained in the fuel cell unit, powered directly by ethanol, are in agreement with the results of voltammetry and chronoamperometry noting the beneficial effect of rare earths in the preparation of electrocatalysts and attesting that the electrocatalysts PtSn/C are more effective than PtRu/C for the oxidation of ethanol.

Oxissulfetos e oxissulfatos de terras raras vêm sendo explorado por vários pesquisadores há algum tempo, e são aplicados como materiais marcadores, LEDs, OLEDs, absorvedores de gases, materiais de persistência em luminescência, ou como marcadores para materiais biológicos, magnéticos entre outros. A proposta deste trabalho foi apresentar um processo diferenciado de obtenção de oxissulfetos e oxissulfatos de terras raras (RE3+) por meio da decomposição térmica de sulfatos e sulfonatos de terras raras [RE = Eu3+, Tb3+, Dy3+, Gd3+ e Sm3+], utilizando o método de precursores para a obtenção dos materiais. Os produtos foram isolados sob atmosferas dinâmicas de ar sintético e de CO, com as temperaturas variando de acordo com os patamares de estabilização dos respectivos compostos. A pureza das fases foi investigada a partir dos difratogramas de raios X (DRX) de cada composto, indicada pelas características cristalinas de cada produto. Os DRX dos precursores Tb(DAS)3·2H2O e Eu(DAS)3·7H2O indicaram que os materiais são amorfos. A pureza, também, foi investigada por espectroscopia de absorção no infravermelho (FTIR), para a identificação dos oxissulfetos e oxissulfatos e, ainda, a partir da interação entre os sulfonatos com os íons Eu3+ e Tb3+. As imagens de microscopia eletrônica de varredura (MEV) mostraram diferenças morfológicas entre os materiais cristalinos de oxissulfeto e/ou oxissulfato e de seus precursores sulfonatos. A partir dessas imagens foi possível perceber algumas características hexagonais e quase esféricas para os Eu2O2S derivados de sulfato e sulfonato, respectivamente, e ainda o grande aumento no tamanho das partículas dos Tb2O2S, derivado de sulfatos e sulfonatos. Também foram observadas diferenças nas formas entre os respectivos oxissulfatos. Os espectros de fotoluminescência dos compostos apresentaram as bandas de emissão das transições intraconfiguracionais oriundas dos íons Eu3+ (5D0→7FJ, J=0-6) e Tb3+ (5D4→7FJ, J=6-0), exibindo as cores vermelha e verde, características dos respectivos íons. Além disso, foram observadas as bandas características dos íons Dy3+ que apareceram no composto Dy2O2S, com a banda mais intensa monitorada a partir da transição 4F9/2→6H13/2 correspondente a cor amarela do íon Dy3+. Também, foi possível observar bandas largas e acentuadas de transferência de carga metal-ligante (LMCT) O2-(2p)→Eu3+ nos compostos Eu2O2S e Eu2O2SO4, tanto derivado de sulfato como de sulfonato. Os resultados mostraram que os oxissulfetos e oxissulfatos apresentam patamares de estabilização térmica sob atmosferas oxidantes e redutoras, que possibilitaram isolar os respectivos produtos. Esses materiais podem ser utilizados como fósforos para diversas aplicações como sondas, lasers entre outros. O Dy2O2S mostrou-se um fósforo estável podendo ser mais explorado em pesquisas futuras em emissões de cor amarela e azul. A troca do ânion sulfato pelo sulfonato proporcionou a obtenção de partículas de maior tamanho, indicando que é possível a aplicação destes fósforos em diferentes áreas tecnológicas. / Rare earth Oxysulfides and oxysulfates have been explored by several researchers for some time, and are applied as labels materials, LEDs, OLEDs, gas absorbers, persistence of luminescence materials, or as markers of biological material, magnetic, among others. The purpose of this study was to present a differentiated process of obtaining oxissulfetos and oxissulfatos rare earth (RE3+) by thermal decomposition of sulfates and sulfonates of rare earths [RE = Eu3+, Tb3+, Dy3+, Gd3+ and Sm3+] using the method precursor to obtain the material. The products were isolated under dynamic atmospheres synthetic air and CO, with temperatures varying according to stabilization levels of the respective compounds.The purity of the phases was investigated from of diffraction of X-rays (XRD) of each compound, indicated by the crystalline characteristics of each product. The XRD of precursors Tb(DAS)3·2H2O and Eu(DAS)3·7H2O indicate that the materials are amorphous. Besides, the purity also was investigated by infrared absorption spectroscopy (FTIR), for identifying and oxissulfetos oxissulfatos and also from the interaction between sulfonates with Eu3+ and Tb3+ ions. The scanning electron microscopy images (SEM) showed morphological differences between crystalline materials oxysulfide and/or oxysulfate and their sulfonate precursors. From these images it was possible to realize almost some hexagonal and quasi-spherical characteristics for Eu2O2S derivatives from sulfate and sulfonate, respectively, and also the large increase in particle size of the Tb2O2S derived from sulfates and sulfonates. Also differences were observed in the shapes between the respective oxysulfates. The photoluminescence spectra of the compounds showed the band emission of intraconfigurational transitions from the Eu3+ (5D0→7FJ, J=0-6) and Tb3+ (5D4→7FJ, J=6-0) ions, displaying the red and green colors, characteristics of the respective ions. In addition, they observed the ions of the characteristic bands Dy3+ that appeared in Dy2O2S compound, with the most intense band monitored from the 4F9/2→6H13/2 transition corresponding to yellow ion Dy3+. Also, it was possible to observe large and sharp bands of metal-ligand charge transfer (LMCT) O2-(2p)→Eu3+ the Eu2O2S and Eu2O2SO4 compounds, both derived sulfate and sulfonate. The results showed that the present oxysulfates and oxysulfides and the levels of thermal stabilization under oxidizing and reducing atmospheres, which made it possible to isolate the respective products. These materials can be used as phosphors for various applications as probes, lasers, among others. The Dy2O2S proved to be stable phosphorus can be further explored in future research in yellow and blue color emissions. The anion exchange of sulfate, sulfonate afforded by obtaining larger particles, indicating that the application of these phosphors in different technological areas is possible.

A cultura de citros exige aplicações constantes de fertilizantes para atingir níveis satisfatórios de produtividade. Fertilizantes contêm outros elementos químicos além daqueles de interesse, como, por exemplo, os elementos terras raras (ETR). Estudos mostram que aplicações de ETR podem aumentar o crescimento e a produtividade das plantas como também causar efeitos nocivos ao ambiente e ao homem. No Brasil, não é prática comum a adição de ETR em fertilizantes, porém alguns insumos contêm em sua composição. Os objetivos deste trabalho foram quantificar os ETR nos compartimentos planta, solo e insumos de agroecossistemas citrícolas, avaliar o modelo de distribuição, identificar as principais fontes de ETR e estudar os efeitos desses elementos na planta cítrica. Para determinação dos ETR, utilizou-se da análise por ativação neutrônica instrumental (INAA) e espectrometria de massas com plasma indutivamente acoplado (ICP-MS). Foram feitos experimentos no campo e em casa-de-vegetação. O experimento de campo foi realizado em quatro propriedades de citros, sendo duas sob sistema de produção orgânico e duas sob o sistema de produção convencional, na região de Borborema, SP, com a variedade Valência (Citrus sinensis L. Osbeck) enxertada sobre limão cravo (Citrus limonia Osbeck),. Amostraram-se 15 plantas em cada propriedade, sendo coletados folhas, frutos, solos e os principais insumos empregados. As concentrações de ETR nas folhas bem como o fator de transferência solo-planta foram semelhantes aos de plantas bioacumuladoras. As folhas assim como as partes do fruto apresentaram depleção de Ce. Na fruta cítrica, a concentração dos ETR apresentou a seguinte distribuição: casca > polpa > sementes = suco. As maiores concentrações de ETR nos insumos foram observadas para os fertilizantes fosfatados. O delineamento experimental utilizado nos dois experimentos em casa-de vegetação foi em blocos ao acaso. Nos experimentos em casa-de-vegetação com superfosfato simples e cloreto de lantânio realizou-se a semeadura de sementes de limão cravo em tubetes de polipropileno. Para o experimento com superfosfato simples, as plantas de limão cravo permaneceram nos tubetes por 6 meses e, a partir desse período, iniciou-se o transplante para sacos plásticos. Os tratamentos constituíram-se de diferentes doses de superfosfato simples (50 g, 100 g, 200 g, 400 g) aplicadas ao substrato. Após 2 meses, coletaram-se as plantas de limão cravo e analisaram-se as folhas e o caule. No experimento com cloreto de lantânio, a aplicação dos tratamentos (50 mg, 100 mg, 200 mg, 400 mg) deuse após 98 dias da semeadura. Três semanas após, coletaram-se as plantas. A planta de citros do estudo pode ser considerada uma bioacumuladora de ETR. Houve discriminação entre os sistemas de produção em 2005, 2006 e 2007 para Eu, Tb, Yb e Sc nos compartimentos solo e folha, com uma concentração significativamente (p<0,05) maior no sistema de produção orgânico. O limão cravo absorve ETR do fertilizante superfosfato simples. A planta de citros teve sua fisiologia alterada com a aplicação de lantânio, isto é, dependendo da dose pode haver um efeito benéfico ou prejudicial no crescimento, sugerindo seu potencial uso como fertilizante na citricultura / The citrus crop requires repeated application of fertilizer to achieve satisfactory levels of productivity. Fertilizers contain other chemical elements in addition to those of interest, such as the rare earth elements (REE). Some studies show that applications of REE may increase plant growth and productivity, but it can also be harmful to both the environment and man. In Brazil, adding REE to fertilizers is not a common practice, however it may be found in the composition of some inputs. The objectives of this study were to quantify the REE in plant, soil and inputs in citrus agroecosystems, to identify the inputs acting as REE sources to the citrus plant, to study the effects of REE in citrus and to evaluate the REE distribution model. The instrumental neutron activation analysis (INAA) and the mass spectrometry with inductively coupled plasma (ICP-MS) were performed to determine the REE. Field and greenhouse experiments were conducted. The field experiment was performed in four citrus properties, with Valencia variety (Citrus sinensis L. Osbeck) grafted onto \'Rangpur\' lime (Citrus limonia Osbeck), two under an organic production system and two under the conventional production system in the region of Borborema, SP. Fifteen plants were sampled in each property and leaves, fruits, soils and the main input used in these properties. REE concentrations in leaves as well as the REE soil-plant transfer factor were similar to those of bioaccumulator plants. Likewise the fruit parts, the leaves showed Ce depletion. The REE concentration in the citrus fruit was distributed as follows: skin > pulp > seeds = juice. The higher concentrations of REE in the inputs were determined for the phosphate fertilizers. The greenhouse experiments with simple superphosphate and lanthanum chloride included the sowing of \'Rangpur\' lime seeds in polypropylene tubes. Both greenhouse experiments had a randomized block design. For the simple superphosphate the \'Rangpur\' lime plants remained in the tubes for 6 months and then were transplanted into plastic bags. The treatments comprised different doses of simple superphosphate (50 g, 100 g, 200 g, 400 g) applied into the substrate. Two months later the \'Rangpur\' lime plants were collected and their leaves and stalk were analyzed. In the experiment with lanthanum chloride heptahydrate the application of the treatments (40 mg, 100 mg, 200 mg, 400 mg) occurred 98 days following sowing. Three weeks following the application of the lanthanum chloride the plants were collected. It can infer that this citrus plant can be considered a REE bioaccumulator. There was discrimination between the production system in 2005, 2006 and 2007 for Eu, Tb, Yb and Sc in the soil and leaves compartments, with a concentration significantly (p <0.05) higher in the organic production system. The \'Rangpur\' lime uptakes REE from the simple superphosphate fertilizer. The citrus plant physiology had changed with the application of lanthanum, ie depending on the dose may be a beneficial or harmful effect on growth, suggesting its potential use as fertilizer in citriculture

Orientador: Fernando Aparecido Sígoli / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Química / Made available in DSpace on 2018-08-22T17:45:52Z (GMT). No. of bitstreams: 1 Souza_ErnestoRezende_D.pdf: 7331362 bytes, checksum: 4797539bb696ec2ceca641cde281f5c6 (MD5) Previous issue date: 2013 / Resumo: Complexos de íons Eu, Gd e Tb contendo ligantes funcionalizados com grupos N-H e S-H foram sintetizados e sistematicamente caracterizados. Foram utilizados ligantes alifáticos e aromáticos de dois grupos: carboxilatos (ácido paminobenzóico, ácido p-mercaptobenzóico, ácido mercaptopropiônico) e b-dicetonatos (acetoacetanilida, tenoiltrifluoroacetona). As propriedades químicas dos complexos foram determinadas por análise elementar, análise termogravimétrica, difração de raios X e espectroscopia vibracional na região do infravermelho. Tais resultados foram correlacionados com os dados da espectroscopia de fotoluminescência, obtidos tanto a 77 K quanto a 300 K, assim como medidas de tempo de vida de emissão, de eficiência quântica e de rendimento quântico absoluto. As energias dos estados tripletos dos ligantes, os parâmetros de intensidade de Judd-Ofelt e os coeficientes de emissão dos complexos com o íon Eu foram determinados experimentalmente. As propriedades luminescentes dos complexos funcionalizados foram comparadas as dos complexos precursores, e alguns dos complexos inéditos apresentam valores de eficiência e de rendimento quânticos maiores do que os valores dos complexos precursores. Através de modelagem molecular utilizando cálculos semi-empíricos e dados oriundos da difração de raios X de monocristal, foram determinados teóricamente os valores de polarizabilidade e de fator de carga dos átomos circunvizinhos do íon Eu nos complexos. A influência da natureza dos ligantes e dos diferentes grupos coordenantes e discutida, bem como a simetria pontual ao redor do íon metálico. Complexos modificados a partir do complexo precursor [Eu(tta)3(H2O)2] apresentam valores de eficiência quântica de até 56%, e de rendimento quântico absoluto de até 36%, sugerindo melhora nos mecanismos de decaimento radiativo / Abstract: Complexes of trivalent gadolinium, europium and terbium ions containing functionalized N¿H and S¿H - ligands, such as: p-aminobenzoic acid, pmercaptobenzoic acid, mercaptopropionic acid, acetoacetanilide and thenoyltrifluoroacetone were synthesized and characterized. The chemical properties of the complexes were determined by elemental analysis, thermogravimetric analysis, X-ray diffraction and Fourier transform infrared spectroscopy. The results were correlated with the data obtained from photoluminescence spectroscopy, collected at 77 K and at 300 K, as well from the emission lifetime, quantum efficiency and absolute quantum yield measurements. In addition, the triplet state energy of the ligands, the Judd-Ofelt intensity parameters and the spontaneous emission coefficients of the Eu ion were experimentally determined. The luminescent properties of the functionalized complexes were compared with the respective properties of the non-functionalized precursor complexes, and some of the new complexes show higher values of quantum efficiency and absolute quantum yield than their precursor complexes. The theoretical polarizability and the charge factor values of the atoms coordinated to the Eu ion in the complexes were estimated from molecular data obtained by modeling using semi empirical methods. The influence of the ligands¿ nature and the coordination modes of different groups are discussed, as well as the symmetries around the metal ions. The water-substituted complexes TMA[Eu(tta)3(L)] (L= paminobenzoate, p-mercaptobenzoate, mercaptopropionate and acetoacetanilide) obtained from [Eu(tta)3(H2O)2] show quantum efficiency up to 56%, and absolute quantum yield up to 36%, suggesting improvements in the radiative decay mechanisms / Doutorado / Quimica Inorganica / Doutor em Ciências

The previously unknown chemical and physical properties of the ternary rare-earth inter­metallic compounds, RETGe (RE=Sc, Y, La–Lu; T=Ag, Au), are investigated using a variety of experimental techniques. The RETGe are found to crystallise in three basic different crystal structure types (CaIn2-, Fe2P-, and CeCu2-type derivatives).

This Thesis describes the syntheses, characterisation and reactivity of rare earth metal boryl and gallyl compounds. Experimental and computational studies were performed to investigate the structure and bonding in these compounds. <b>Chapter 1</b> introduces key metal-boryl and metal-gallyl compounds of the s, p, d and f-blocks via literature review. <b>Chapter 2</b> describes the syntheses, structures and bonding analyses of rare earth metal boryl compounds. A short introduction to rare earth metal cations is given. Chapter 3</b> describes the syntheses, structures and bonding analyses of rare earth metal gallyl compounds. The preparation of a new class of rare earth metal cations will also be reported. A short introduction to rare earth metal amidinates is given. <b>Chapter 4</b> presents reactivity studies of the rare earth metal gallyl compounds described in Chapter 3. To facilitate a direct structure and reactivity comparison, the corresponding boryl compounds were also synthesised. The results of a comprehensive DFT computational study to investigate the structure and bonding in these compounds are also presented. A short introduction to metalelement and metalmetal bond reactivity is given. <b>Chapter 5</b> presents full experimental procedures and characterising data for the new compounds reported. <b>Appendix<b> <b>CD Appendix</b> contains .cif files for all new crystallographically characterised compounds described.

>Magister Scientiae - MSc / In the past few decades, the studies of f-electron materials have revealed unusual physical properties such as Fermi-liquid, non-Fermi-liquid behaviour at low temperatures, heavy- Fermion behaviour, valence fluctuation, Kondo effect, superconducting and magnetic ordering. These materials include binary and ternary compounds and alloys with Cerium (Ce) or Ytterbium (Yb) based rare earth elements or Uranium (U) based actinide element. In these systems the localized magnetic moments formed by Ce, Yb or U ions transform the electronic properties of these compounds leading to quasiparticles with masses in excess to 1000 times the bare electron mass. These materials are known as heavy-fermion materials. Two well known heavy – Fermion compounds with Ce based rare earth elements of interest in this thesis are CePt₂Si₂ and CeCu₅In. The effect of substituting Ce with moment bearing Tb or Dy in these two compounds, are reported through measurements of electrical resistivity, magnetic susceptibility and magnetization. The three alloy systems (Ce₁₋ₓREₓ)Pt₂Si₂ (RE = Tb, Dy) and (Ce₁₋ₓTbᵪ)Cu₅In under investigation in the present thesis, was synthesized and characterized by x-ray diffraction. The alloy systems (Ce₁₋ₓREₓ)Pt₂Si₂ (RE = Tb, Dy, 0≤ ᵡ ≤1) formed a single phase in the P4/nmm tetragonal CaBe₂Ge₂ – type structure across the whole series while the (Ce₁₋ₓTbᵪ)Cu₅In alloy system formed a single phase in the Pnma orthorhombic CeCu₆ – type crystal structure up to 40% Ce substitution. The physical properties of these systems is reported and discussed through the measurements of electrical resistivity, magnetic susceptibility and magnetization. The variables of this study are: the doping concentration of Tb or Dy, the applied magnetic field and the sample temperature. Electrical resistivity studies for all the systems revealed coherence effect at Ce – rich alloys (0≤ ᵡ ≤0.2) and single-ion Kondo scattering with further increased RE concentration ( ᵡ ≥ 0.3). The magnetic property studies indicate antiferromagnetic ordering only for the (Ce₁₋ₓREₓ)Pt₂Si₂ alloy system in the concentration range 0.7≤ ᵡ ≤ 1. The present thesis is comprised of six chapters, which are arranged as follows: The first chapter deals with the theoretical background of the physical properties of Ce based intermetallics compounds and alloys. Experimental techniques constitutes chapter II and explains the techniques used in this study. The theoretical overview of the two parent compounds of interest in this thesis (CePt₂Si₂ and CeCu₅In) is presented in chapter III. The fourth and the fifth chapters of this study deals with results and discussion. The thesis is completed with a conclusion in chapter six.

Ce travail de thèse porte sur l'incorporation de charges minérales d'oxyde d'erbium, Er2O3, et d'oxyde de praséodyme, Pr6O11, dans une matrice polymère de type élastomère, ceci dans le cadre d'un projet industriel de remplacement du plomb dans des équipements de radioprotection. L'objet de cette thèse était d'améliorer la dispersion des charges au sein de la matrice par le biais de procédés de traitements chimiques de ces particules. Divers types de fonctionnalisations de surface ont été employés afin de compatibiliser celles-ci avec une matrice organique, notamment par greffage de composés de type acides phosphoniques. Plusieurs acides phosphoniques ont ainsi pu être utilisés avec succès pour la fonctionnalisation des deux types de charges. La caractérisation de ces différentes fonctionnalisations représente une part importante de ce projet. Des techniques d'analyse innovantes, aussi bien directes qu'indirectes ont été employées dans ce but, à savoir de la Py-GC/MS pour la détection des composés ancrés à la surface des charges, de la fluorescence X et de la spectroscopie infrarouge dans un objectif de quantification, mais aussi des études cinétiques de sédimentation des charges dans un milieu liquide organique. Finalement, des composites ont pu être obtenus par mélange des charges, traitées et non traitées, avec une matrice polyuréthane. Des essais de traction ont permis de montrer clairement une amélioration des propriétés mécaniques de certains des composites, grâce à la fonctionnalisation des charges par les acides phosphoniques. / This thesis focuses on the incorporation of mineral fillers of erbium oxide, Er2O3, and praseodymium oxide, Pr6O11, in an elastomeric polymer matrix, in the context of an industrial project to replace the lead in radiation protection equipment. The actual purpose of this thesis was to improve the dispersion of the fillers in the matrix through chemical treatment processes of these particles. Various types of surface functionalization were used to compatibilize them with an organic matrix, in particular by grafting compounds such as phosphonic acids. Hence, several phosphonic acids have been successfully used for the functionalization of both types of fillers. The characterization of these functionalizations is an important part of this project. Innovative analysis techniques, both direct and indirect have been used for this purpose, namely Py-GC/MS to detect the chemical compounds anchored to the surface of the fillers, X-ray fluorescence and FTIR spectroscopy with a quantification target, but also a study of sedimentation kinetics of the fillers in an organic medium. Finally, composites were obtained by mixing the fillers, untreated and treated, with a polyurethane matrix. Tensile tests have clearly shown an improvement of mechanical properties for some of the composites, due to the functionalization of the fillers by phosphonic acids.

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