Pyrolysis-capillary gas chromatography combined with FID, ECD and MS detection were used to characterize refuse-derived fuel and aquatic fulvic acids. Different pyrolysis methods and programs were evaluated. Pyrolysis temperatures of 700-800°C produced the strongest signal for organics present in RDF and fulvic acid. Cellulose and fatty acids pyrolyzates were identifiable by GC-MS following preparative pyrolysis fractionation. At organic chloride content of 0.023%, only three halogenated compounds were detected in the GC-MS of the fractions. None of the priority pollutants were detected at lower detection limit of 0.72 to 24 mg/ kg RDF. Selective solvent extraction improves the reproduciblities of the technique and allows the detection of polymeric structures. Pyrograms of polyvinyl chloride and regular typing paper showed some common peaks that are present in the RDF pyrogram. About 65% of the peaks in the RDF pyrogram might be of paper origin. The organic chloride content of the RDF was evaluated by ion chromatography of the trapped pyrolyzates in 2% NaOH trap and it was found to be 221 mg Cl/ kg dry RDF. Pyrolysis conditions and temperature programs for FA were systematically evaluated. Samples included purified FA, methylated FA and HPLC separated fractions. Characteristic pyrograms were developed. Profiles of benzene, toluene, phenol, m-cresol and biphenyl from FA were evaluated. The production of phenol was the largest at 800°C, at concentration of 1.61 mg per gram of FA pyrolyzed. The profiles of benzene and toluene followed the same pathways. Both pyrolyzates had at least two precursors. HPLC fractions of FA showed some regular retention patterns characteristic of polymeric material. DL-proline, seriene and vanillic acid pyrograms showed some peaks with the same retention times as those in FA pyrogram under the same conditions. A reproducibility of 6% relative standard deviation was achieved in the pyrolysis of RDF and 0.91% in the case of FA.

Nos últimos anos, acentuou-se o interesse em materiais semicondutores com alto número atômico e larga banda de energia proibida para aplicações na detecção de radiação ionizante à temperatura ambiente, usando o método direto de detecção. Alguns materiais como o PbI2, HgI2, TlBr, CdTe and CdZnTe são bons fotocondutores e podem ser usados à temperatura ambiente. Como um bom candidato, o PbI2 apresenta uma banda de energia proibida acima de 2,0 eV, o qual quando operando à temperatura ambiente apresenta um baixo ruído, baixa corrente de fuga e alta coleta de cargas. O alto poder de frenamento da radiação ionizante é devido ao alto número atômico e alta densidade. Pesquisadores buscam métodos alternativos que minimizem o tempo de deposição e barateiem o custo dos filmes finos de materiais semicondutores candidatos em aplicações médicas, como detector de raios-X à temperatura ambiente para radiografias digitais. Neste sentido, apresentamos dois métodos para a deposição de filmes finos policristalinos de iodeto de chumbo (PbI2). As técnicas de spray pyrolysis (SP) e evaporação de solvente em estufa (ES) foram usadas para a fabricação de filmes finos de PbI2 com relativo baixo tempo de deposição. A técnica de SP foi adotada com o uso de água milli-Q e N.N-dimetilformamida (DMF) como solventes, variando os parâmetros de deposição. No primeiro caso, para uma deposição otimizada na temperatura de 225ºC e concentração de solução de PbI2 3,1 g/l, uma taxa de deposição de aproximadamente 3,3 Ås-1 foi obtida. O solvente orgânico DMF foi usado para dissolver o PbI2 com alta eficiência no crescimento do material, sendo que uma taxa de crescimento de 20Å/s até 50 Å/s foi obtida como uma função da taxa de solução e um comportamento linear foi observado. Posteriormente, usando a técnica de ES, foram depositados filmes finos usando DMF como solvente com concentração de 150 g/l. Filmes de 6 ?m de espessura foram obtidos com substratos completamente recobertos. Ambos os filmes depositados com DMF (spray pyrolysis e evaporação de solvente) apresentaram cristalização do politipo 4H. No entanto, a cristalização nessa forma se mostra com menor ocorrência nos filmes depositados por evaporação de solvente, indicando um maior grau de ordenamento cristalino nesse material. Em adição, os detectores produzidos com os filmes finos foram expostos aos raios-X na faixa de diagnóstico mamografico usando uma fonte de raios-X com anodo de molibdênio (Mo) com filtro de Al de 0,5 mm de espessura. A fotocorrente é comparada com a corrente no escuro e uma resposta linear foi observada em função da exposição. / In the last few years, great interest has been focused to high atomic number and wide band gap semiconductor materials for applications in room temperature ionizing radiation detection using the direct detection method. Some materials such as PbI2, HgI2, TlBr, CdTe and CdZnTe are good photoconductors and can be used at room temperature. As a good candidate, PbI2 presents a wide band gap (above 2.0 eV), what leads to low noise, low leakage current and large charge collection when the device is operated at room temperature. The high photon stopping power for ionizing radiation is due to the high atomic number and high density. Researchers seek alternative methods that minimize the time of deposition of thin films of promising semiconductor materials candidates for medical applications, such as room temperature X-rays detectors for digital radiography. For this application, large areas are also necessary. In this sense, we investigated two alternative methods for the deposition of polycrystalline thin films of lead iodide (PbI2). The spray pyrolysis (SP) and solution evaporation (ES) deposition techniques were used for fabrication of PbI2 thin films with relative low deposition time. The SP technique was adopted using milli-Q water and N.N-dimethylformamide (DMF) as solvents under varying deposition parameters. In the first case, for an optimized deposition temperature of 225ºC and concentration of PbI2 of 3.1 g/l a deposition rate of about 3.3 Å/s was obtained. The DMF organic solvent was used for dissolution of the PbI2 with higher efficiency on the growth of the film. A growth rate varying from 20 Å/s up to 50 Å/s was obtained as a function of solution rate and a linear behavior could be observed. After, using the ES technique, were obtained thin films deposited using DMF as solvent with concentration of 150 g/l. Thin films 6 ?m-thick were obtained with full coverage of the substrates. In addition, the detectors produced using the thin films were also exposed to X-ray in the range of mammography diagnosis, using as X-ray source a molybdenum (Mo) anode with 0.5 mm Al filtration. The photocurrent is compared to the dark current and a linear response was observed as a function of exposure.

L’Afrique de l'Ouest manque de ressources naturelles pour la production d'énergie. Les sous-produits agro-industriels comme les coques d’anacarde (CNS), les tourteaux de jatropha et de karité ont été identifiés comme des ressources disponibles et facilement mobilisables à des fins énergétiques. Ces biomasses se caractérisent par de fortes teneurs en extractibles (baume de cajou=CNSL ou triglycérides), sources de fumées toxiques en combustion. La thèse visait à évaluer la pertinence de la pyrolyse rapide comme procédé alternatif pour ces ressources, etplus particulièrement à établir l'impact des extractibles sur les rendements, la composition et la stabilité des bio-huiles. Les biomasses ont été dérivées en échantillons couvrant la gamme entière des teneurs en extractibles (tourteau déshuilé ~0% ; extractible purs 100%), lesquels ont été caractérisés et pyrolysés dans 2 dispositifs laboratoires (ATG et four tubulaire), puis en conditions réelles sur un pilote de pyrolyse rapide à lit fluidisé. On ne constate pas d'interaction significative entre la matrice solide et les extractibles lors de leur décomposition, mais des produits différents ont été identifiés. Le CNSL se volatilise entre 250 et 320°C ; plusieurs composés phénoliques ou typiques du CNSL brut se retrouvent dans l'huile de pyrolyse. En revanche, les triglycérides se décomposent entièrement entre 380 et 420°C en chaînes d’hydrocarbures linéaires. Quelques produits d'interaction avec les triglycérides et les protéines ont été identifiés. Par ailleurs, les essais sur pilote ont mis en évidence des difficultés opérationnelles dans le lit fluidisé liées aux spécificités des tourteaux, suggérant une optimisation des conditions opératoires. Pour pallier la séparation de phases constatée sur les bio-huiles, des formulations avec d'autres biocarburants ont été testées. Les émulsions obtenues sont plus homogènes, mais leur stabilité physique est encore insuffisante malgré l'ajout / Sub-Saharan West Africa lacks of natural resources, especially for energy production. By-products of agro-industry as cashew nut shells (CNS), jatropha (Jc) and shea (Sc) press cakes were identified as available resources for energetic valorisation. These biomasses are characterized by high extractive contents (cashew nut shell liquid/CNSL or triglycerides) which are the reason for toxic fumes during combustion. The thesis investigated the feasibility of flash pyrolysis as alternative process for these resources, more specifically the impact of the extractives on yields, the composition and the stability of flash pyrolysis oils. The feedstock were derived into samples covering the whole range of extractive contents (from de-oiled press cakes, ~0 wt%; to pure extractives, 100 wt%) which were characterized and pyrolysed in two laboratory devices (TGA and tubular furnace), then by applying flash pyrolysis conditions in a fluidized bed reactor. No significant interaction in-between the solid matrix and the extractives during pyrolysis were observed but different products were identified. CNSL volatises between 250 and 320°C, several phenolic compounds and typical compounds of crude CNSL were found to be present in the pyrolysis oil. In contrast, triglycerides are entirely decomposed at 380 to 420°C to give linear hydro-carbon chains. Some interaction products of the triglycerides with proteins were identified. Additionally, the experiments with the pilot plant have shown operational difficulties in the fluidized bed, which are linked to specific properties of the press cakes. Thus, further optimisations of process conditions are suggested. To overcome the observed phase separation of the pyrolysis oils mixtures with other biofuels were studied. The obtained emulsions are more homogeneous but the physical stability is still insufficient despite the addition of surfactants.

O iodeto de mercúrio(HgI2) vem sendo largamente estudado com o objetivo de utilizá-lo em detectores de radiação –X e –γ. Este material semicondutor apresenta propriedades interessantes que o tornam um grande candidato a esta aplicação em relação a outros materiais. Suas propriedades são gap óptico largo (2,13 eV), alto numero atômico (ZHg = 80; ZI = 53) e alto coeficiente de absorção para comprimentos de onda da ordem de energia do raios-X e -γ. Este, também, pode apresentar três fases quando sólido: fase vermelha (ou α-HgI2), fase amarela (ou β-HgI2) e fase laranja. Cada uma destas fases é associada com diferentes estruturas cristalinas. O α-HgI2 é tetragonal, o HgI2 laranja é também tetragonal,diferindo da fase vermelha somente na posição dos átomos de mercúrio, e β-HgI2 é ortorrômbico. Neste trabalho, estes materiais foram obtidos por duas técnicas: spray pyrolysis e evaporação de solvente. Nas duas técnicas os mais importantes parâmetros para a obtenção das diferentes estruturas são a temperatura e a taxa de evaporação do solvente. Através do método de spray pyrolysis foi possível obter filmes finos de HgI2 com duas estruturas diferentes, somente variando a temperatura do aquecedor de substratos e o solvente. Acima da temperatura de 100ºC com o solvente água foi possível obter filmes amarelados de HgI2. Por sua vez, a temperatura abaixo de 100ºC com o solvente etanol foi possível obter filmes avermelhados. Com a técnica de evaporação de solvente foi possível obter cristais e filmes laterais variando somente a taxa de evaporação de solvente. Variaram-se as taxas de evaporação entre rápida(~10ml/h), média(~0,5ml/h), lenta(~0,1ml/h) e super-lenta(~0,01ml/h). Para a taxa de evaporação média e lenta foram obtidos filmes laterais. Já para a taxa super-lenta foi possível obter cristais. Outro ponto estudado foi a influência da luz no crescimento dos cristais: no escuro obteve-se cristais maiores que os submetidos a luz ambiente. Todos os filmes foram caracterizados por difração de raios-X, microscopia eletrônica de varredura (MEV), e espectroscopia de dispersão de energia (EDS). Já os cristais foram caracterizados por difração de raios-X, MEV e espalhamento Raman. / Recently, attention has been devoted to the study of mercuric iodide (HgI2) because this material is a strong candidate for the development of X- and γ -ray detectors. This material has an optical gap of 2.13 eV, high atomic number (ZHg = 80; ZI = 53) and high absorption coefficient for radiation in the wavelength region of X- and γ –rays. When solid, three phases can be obtained: red (or α-HgI2), yellow (or β-HgI2) and orange. Each of these phases has a different crystalline structure: α-HgI2 is tetragonal, as it is the orange- HgI 2 (the difference is that for the last one the mercury atoms sits in different positions), while the β-HgI2 is orthorhombic. In this work we obtained these materials using two different techniques: spray pyrolysis and solvent evaporation. For both of them the most important parameters are the deposition temperature and solvent evaporation rate. Thin films with two different structures were obtained by spray pyrolysis varying the substrate temperature and the solvent. Using water as solvent and deposition temperature above 100ºC we obtained yellow HgI2. When the temperature is reduced below that value and the solvent is ethanol, red films were obtained. For the solvent evaporation technique, lateral films and millimeter-sized crystals were obtained by varying the solvent evaporation rate. For ethanol as solvent we used four evaporation rates named as fast(~10ml/h), medium (~0.5ml/h), slow (~0.1ml/h) and super-slow (~0.01ml/h). For the medium and slow evaporation rates lateral films were obtained on the wall of the reservoir. For the super-slow evaporation rate crystals were obtained at the bottom of the reservoir. We observed that light has a tremendous influence on crystal growth: bigger crystals are obtained in the dark than under ambient light illumination. As characterization techniques we used: X-rays diffraction, Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS), and Raman Scattering.

Pyrolysis of biomass consists of heating solid biomass inthe absence of air to produce solid, liquid and gaseous fuels.In the first part of this thesis rapid pyrolysis of wood(birch) and some agricultural residues (olive waste, sugarcanebagasse and wheat straw in untreated and in pelletized form) athigh temperature (800ºC–1000ºC) is studied ina free fall reactor at pilot scale. These conditions are ofinterest for gasification in fluidized beds. Of main interestare the gas and char yields and compositions as well as thereactivity of the produced char in gasification. A higher temperature and smaller particles increase theheating rate resulting in a decreased char yield. The crackingof the hydrocarbons with an increase of the hydrogen content inthe gaseous product is favoured by a higher temperature and byusing smaller particles. Wood gives more volatiles and lesschar than straw and olive waste. The higher ash content inagricultural residues favours the charring reactions. Charsfrom olive waste and straw are more reactive in gasificationthan chars from birch because of the higher ash content. Thecomposition of the biomass influences the product distribution.Birch and bagasse give more volatiles and less char thanquebracho, straw and olive waste. Longer residence time inrapid pyrolysis increase the time for contact between tar andchar which makes the char less reactive. The secondary charproduced from tar not only covers the primary char but alsoprobably encapsulates the ash and hinders the catalytic effectof the ash. High char reactivity is favoured by conditionswherethe volatiles are rapidly removed from the particle, i.e.high heating rate, high temperature and small particles. The second part of this thesis deals with slow pyrolysis inpresence of steam for preparation of active carbon. Theinfluence of the type of biomass, the type of reactor and thetreatment conditions, mainly temperature and activation time,on the properties and the yield of active carbons are studied.The precursors used in the experiments are birch (wood) anddifferent types of agricultural residues such as sugarcanebagasse, olive waste, miscanthus pellets and straw in untreatedand pelletized form. The results from the pyrolysis of biomass in presence ofsteam are compared with those obtained in inert atmosphere ofnitrogen. The steam contributes to the formation of solidresidues with high surface area and good adsorption capacity.The yield of liquid products increases significantly at theexpense of the gaseous and solid products. Large amount ofsteam result in liquid products consisting predominantly ofwater-soluble polar compounds. In comparison to the stationary fixed bed reactor, therotary reactor increases the production of energy-rich gases atthe expense of liquid products. The raw materials have strong effect on the yields and theproperties of the pyrolysis products. At equal time oftreatment an increase of the temperature results in a decreaseof the yield of solid residue and improvement of the adsorptioncapacity until the highest surface area is reached. Furtherincrease of the temperature decreases the yield of solidproduct without any improvement in the adsorption capacity. Therate of steam flow influences the product distribution. Theyield of liquid products increases while the gas yielddecreases when the steam flow is increased. <b>Keywords</b>: rapid pyrolysis, pyrolysis, wood, agriculturalresidues,biomass, char, tar, gas, char reactivity,gasification, steam, active carbon

No description available.

<p>Pyrolysis of biomass consists of heating solid biomass inthe absence of air to produce solid, liquid and gaseous fuels.In the first part of this thesis rapid pyrolysis of wood(birch) and some agricultural residues (olive waste, sugarcanebagasse and wheat straw in untreated and in pelletized form) athigh temperature (800ºC–1000ºC) is studied ina free fall reactor at pilot scale. These conditions are ofinterest for gasification in fluidized beds. Of main interestare the gas and char yields and compositions as well as thereactivity of the produced char in gasification.</p><p>A higher temperature and smaller particles increase theheating rate resulting in a decreased char yield. The crackingof the hydrocarbons with an increase of the hydrogen content inthe gaseous product is favoured by a higher temperature and byusing smaller particles. Wood gives more volatiles and lesschar than straw and olive waste. The higher ash content inagricultural residues favours the charring reactions. Charsfrom olive waste and straw are more reactive in gasificationthan chars from birch because of the higher ash content. Thecomposition of the biomass influences the product distribution.Birch and bagasse give more volatiles and less char thanquebracho, straw and olive waste. Longer residence time inrapid pyrolysis increase the time for contact between tar andchar which makes the char less reactive. The secondary charproduced from tar not only covers the primary char but alsoprobably encapsulates the ash and hinders the catalytic effectof the ash. High char reactivity is favoured by conditionswherethe volatiles are rapidly removed from the particle, i.e.high heating rate, high temperature and small particles.</p><p>The second part of this thesis deals with slow pyrolysis inpresence of steam for preparation of active carbon. Theinfluence of the type of biomass, the type of reactor and thetreatment conditions, mainly temperature and activation time,on the properties and the yield of active carbons are studied.The precursors used in the experiments are birch (wood) anddifferent types of agricultural residues such as sugarcanebagasse, olive waste, miscanthus pellets and straw in untreatedand pelletized form.</p><p>The results from the pyrolysis of biomass in presence ofsteam are compared with those obtained in inert atmosphere ofnitrogen. The steam contributes to the formation of solidresidues with high surface area and good adsorption capacity.The yield of liquid products increases significantly at theexpense of the gaseous and solid products. Large amount ofsteam result in liquid products consisting predominantly ofwater-soluble polar compounds.</p><p>In comparison to the stationary fixed bed reactor, therotary reactor increases the production of energy-rich gases atthe expense of liquid products.</p><p>The raw materials have strong effect on the yields and theproperties of the pyrolysis products. At equal time oftreatment an increase of the temperature results in a decreaseof the yield of solid residue and improvement of the adsorptioncapacity until the highest surface area is reached. Furtherincrease of the temperature decreases the yield of solidproduct without any improvement in the adsorption capacity. Therate of steam flow influences the product distribution. Theyield of liquid products increases while the gas yielddecreases when the steam flow is increased.</p><p><b>Keywords</b>: rapid pyrolysis, pyrolysis, wood, agriculturalresidues,biomass, char, tar, gas, char reactivity,gasification, steam, active carbon</p>

Solid oxide fuel cell (SOFC) research is currently underway to improve performance, cost and durability by lowering the operating temperature to ~600°C. One approach is to design fabrication processes capable of tailoring desirable cathode microstructures to enhance mass and charge transfer properties through the porous medium. The aim of this study is to develop a cost effective fabrication technique for deposition of novel microstructures, specifically, functionally graded thin films of LSM oxide with porosity graded structure for use as IT- SOFCs cathode. Spray pyrolysis method was chosen as a low-temperature processing technique for deposition of porous LSM films onto dense YSZ substrates. The effort was directed toward the optimization of the processing conditions for deposition of high quality LSM films with variety of morphologies in the range of dense to porous microstructures. Results of optimization studies on spray parameters revealed that the substrate surface temperature is the most critical parameter influencing the roughness and morphology, porosity, cracking and crystallinity of the film. Physical and chemical properties of deposited thin films such as porosity, morphology, phase crystallinity and compositional homogeneity have shown to be extensively dependent on the deposition temperature as well as solution flow rate and the type of precursor solution among other parameters. The LSM film prepared from organo-metallic precursor and organic solvent showed a homogeneous crack-free microstructure before and after heat treatment as opposed to aqueous solution. Also, increasing the deposition temperature and the solution flow rate, in the specific range of 520-580 ℃ and 0.73-1.58 ml/min, respectively, leads to change the microstructure from a dense to a highly porous film. Taking the advantage of simplicity of spray pyrolysis technique combined with using metal-organic compounds, the conventional ultrasonic spray system was modified to a novel system whereby highly crystalline multi-layered porosity graded LSM cathode with columnar morphology and good electrical conductivity in the range of 500-700 °C was fabricated through a multi-step spray and via applying optimum combination of spray parameters. This achievement for the current graded LSM cathode would allow its use in IT-SOFCs.

Nos últimos anos, acentuou-se o interesse em materiais semicondutores com alto número atômico e larga banda de energia proibida para aplicações na detecção de radiação ionizante à temperatura ambiente, usando o método direto de detecção. Alguns materiais como o PbI2, HgI2, TlBr, CdTe and CdZnTe são bons fotocondutores e podem ser usados à temperatura ambiente. Como um bom candidato, o PbI2 apresenta uma banda de energia proibida acima de 2,0 eV, o qual quando operando à temperatura ambiente apresenta um baixo ruído, baixa corrente de fuga e alta coleta de cargas. O alto poder de frenamento da radiação ionizante é devido ao alto número atômico e alta densidade. Pesquisadores buscam métodos alternativos que minimizem o tempo de deposição e barateiem o custo dos filmes finos de materiais semicondutores candidatos em aplicações médicas, como detector de raios-X à temperatura ambiente para radiografias digitais. Neste sentido, apresentamos dois métodos para a deposição de filmes finos policristalinos de iodeto de chumbo (PbI2). As técnicas de spray pyrolysis (SP) e evaporação de solvente em estufa (ES) foram usadas para a fabricação de filmes finos de PbI2 com relativo baixo tempo de deposição. A técnica de SP foi adotada com o uso de água milli-Q e N.N-dimetilformamida (DMF) como solventes, variando os parâmetros de deposição. No primeiro caso, para uma deposição otimizada na temperatura de 225ºC e concentração de solução de PbI2 3,1 g/l, uma taxa de deposição de aproximadamente 3,3 Ås-1 foi obtida. O solvente orgânico DMF foi usado para dissolver o PbI2 com alta eficiência no crescimento do material, sendo que uma taxa de crescimento de 20Å/s até 50 Å/s foi obtida como uma função da taxa de solução e um comportamento linear foi observado. Posteriormente, usando a técnica de ES, foram depositados filmes finos usando DMF como solvente com concentração de 150 g/l. Filmes de 6 ?m de espessura foram obtidos com substratos completamente recobertos. Ambos os filmes depositados com DMF (spray pyrolysis e evaporação de solvente) apresentaram cristalização do politipo 4H. No entanto, a cristalização nessa forma se mostra com menor ocorrência nos filmes depositados por evaporação de solvente, indicando um maior grau de ordenamento cristalino nesse material. Em adição, os detectores produzidos com os filmes finos foram expostos aos raios-X na faixa de diagnóstico mamografico usando uma fonte de raios-X com anodo de molibdênio (Mo) com filtro de Al de 0,5 mm de espessura. A fotocorrente é comparada com a corrente no escuro e uma resposta linear foi observada em função da exposição. / In the last few years, great interest has been focused to high atomic number and wide band gap semiconductor materials for applications in room temperature ionizing radiation detection using the direct detection method. Some materials such as PbI2, HgI2, TlBr, CdTe and CdZnTe are good photoconductors and can be used at room temperature. As a good candidate, PbI2 presents a wide band gap (above 2.0 eV), what leads to low noise, low leakage current and large charge collection when the device is operated at room temperature. The high photon stopping power for ionizing radiation is due to the high atomic number and high density. Researchers seek alternative methods that minimize the time of deposition of thin films of promising semiconductor materials candidates for medical applications, such as room temperature X-rays detectors for digital radiography. For this application, large areas are also necessary. In this sense, we investigated two alternative methods for the deposition of polycrystalline thin films of lead iodide (PbI2). The spray pyrolysis (SP) and solution evaporation (ES) deposition techniques were used for fabrication of PbI2 thin films with relative low deposition time. The SP technique was adopted using milli-Q water and N.N-dimethylformamide (DMF) as solvents under varying deposition parameters. In the first case, for an optimized deposition temperature of 225ºC and concentration of PbI2 of 3.1 g/l a deposition rate of about 3.3 Å/s was obtained. The DMF organic solvent was used for dissolution of the PbI2 with higher efficiency on the growth of the film. A growth rate varying from 20 Å/s up to 50 Å/s was obtained as a function of solution rate and a linear behavior could be observed. After, using the ES technique, were obtained thin films deposited using DMF as solvent with concentration of 150 g/l. Thin films 6 ?m-thick were obtained with full coverage of the substrates. In addition, the detectors produced using the thin films were also exposed to X-ray in the range of mammography diagnosis, using as X-ray source a molybdenum (Mo) anode with 0.5 mm Al filtration. The photocurrent is compared to the dark current and a linear response was observed as a function of exposure.

O iodeto de mercúrio(HgI2) vem sendo largamente estudado com o objetivo de utilizá-lo em detectores de radiação –X e –&#947;. Este material semicondutor apresenta propriedades interessantes que o tornam um grande candidato a esta aplicação em relação a outros materiais. Suas propriedades são gap óptico largo (2,13 eV), alto numero atômico (ZHg = 80; ZI = 53) e alto coeficiente de absorção para comprimentos de onda da ordem de energia do raios-X e -&#947;. Este, também, pode apresentar três fases quando sólido: fase vermelha (ou &#945;-HgI2), fase amarela (ou &#946;-HgI2) e fase laranja. Cada uma destas fases é associada com diferentes estruturas cristalinas. O &#945;-HgI2 é tetragonal, o HgI2 laranja é também tetragonal,diferindo da fase vermelha somente na posição dos átomos de mercúrio, e &#946;-HgI2 é ortorrômbico. Neste trabalho, estes materiais foram obtidos por duas técnicas: spray pyrolysis e evaporação de solvente. Nas duas técnicas os mais importantes parâmetros para a obtenção das diferentes estruturas são a temperatura e a taxa de evaporação do solvente. Através do método de spray pyrolysis foi possível obter filmes finos de HgI2 com duas estruturas diferentes, somente variando a temperatura do aquecedor de substratos e o solvente. Acima da temperatura de 100ºC com o solvente água foi possível obter filmes amarelados de HgI2. Por sua vez, a temperatura abaixo de 100ºC com o solvente etanol foi possível obter filmes avermelhados. Com a técnica de evaporação de solvente foi possível obter cristais e filmes laterais variando somente a taxa de evaporação de solvente. Variaram-se as taxas de evaporação entre rápida(~10ml/h), média(~0,5ml/h), lenta(~0,1ml/h) e super-lenta(~0,01ml/h). Para a taxa de evaporação média e lenta foram obtidos filmes laterais. Já para a taxa super-lenta foi possível obter cristais. Outro ponto estudado foi a influência da luz no crescimento dos cristais: no escuro obteve-se cristais maiores que os submetidos a luz ambiente. Todos os filmes foram caracterizados por difração de raios-X, microscopia eletrônica de varredura (MEV), e espectroscopia de dispersão de energia (EDS). Já os cristais foram caracterizados por difração de raios-X, MEV e espalhamento Raman. / Recently, attention has been devoted to the study of mercuric iodide (HgI2) because this material is a strong candidate for the development of X- and &#947; -ray detectors. This material has an optical gap of 2.13 eV, high atomic number (ZHg = 80; ZI = 53) and high absorption coefficient for radiation in the wavelength region of X- and &#947; –rays. When solid, three phases can be obtained: red (or &#945;-HgI2), yellow (or &#946;-HgI2) and orange. Each of these phases has a different crystalline structure: &#945;-HgI2 is tetragonal, as it is the orange- HgI 2 (the difference is that for the last one the mercury atoms sits in different positions), while the &#946;-HgI2 is orthorhombic. In this work we obtained these materials using two different techniques: spray pyrolysis and solvent evaporation. For both of them the most important parameters are the deposition temperature and solvent evaporation rate. Thin films with two different structures were obtained by spray pyrolysis varying the substrate temperature and the solvent. Using water as solvent and deposition temperature above 100ºC we obtained yellow HgI2. When the temperature is reduced below that value and the solvent is ethanol, red films were obtained. For the solvent evaporation technique, lateral films and millimeter-sized crystals were obtained by varying the solvent evaporation rate. For ethanol as solvent we used four evaporation rates named as fast(~10ml/h), medium (~0.5ml/h), slow (~0.1ml/h) and super-slow (~0.01ml/h). For the medium and slow evaporation rates lateral films were obtained on the wall of the reservoir. For the super-slow evaporation rate crystals were obtained at the bottom of the reservoir. We observed that light has a tremendous influence on crystal growth: bigger crystals are obtained in the dark than under ambient light illumination. As characterization techniques we used: X-rays diffraction, Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS), and Raman Scattering.