La première partie de cette thèse décrit l'élaboration et la caractérisation de couches minces supraconductrices de composition YBa2Cu3O7-d. Leurs propriétés de transport ont été analysées dans le cadre de la théorie B.C.S. La deuxième partie est relative à la mise en évidence et à l'étude des propriétés structurales de nouvelles perovskites de composition Ln2CuTiO6-d (Ln=terre rare) et AxLn2-xCu1+yTi1-yO6-d (A=alcalinoterreux). Un modèle de distribution cationique reposant sur des études de diffraction X et de microscopie électronique est proposé.

L'objectif de cet étude est de donner une caractérisation complète<br />de la structure locale de deux classes de composés : les manganites<br />de lanthane droguées avec du sodium et les doubles perovskites de<br />ferro-molybdène droguées avec du tungstène. Les deux classes se<br />comportent, en général comme de conducteurs dans leur phase<br />ferromagnétique et, suivant variations de température ou de dopage,<br />ils subissent une transition métal-isolant à laquelle il faut<br />associer une transition<br />ferromagnétique-paramagnétique(antiferromagnétique). En effet, il<br />est tout à fait accepté que aussi bien dans les manganites, que dans<br />les perovskites doubles, les propriétés de transport sont<br />influencées d'une façon importante par la structure locale (longueur<br />et angle de liaison) autour des sites clés occupés par des ions<br />magnétiques. Pour cette raison la spectroscopie d'absorption de<br />rayon X, en étant sensible à l'ordre locale autour de l'atome<br />absorbeur, constitue la technique la plus adaptée pour l'étude de<br />ces composés. La structure locale de film fins de manganite droguées<br />avec du sodium a été étudiée en fonction de l'épaisseur des film.<br />Des échantillons de poudre de perovskites double droguées avec<br />tungstène ont été étudiées pour en caractériser la structure locale<br />en fonction du dopage et pour chercher de comprendre la nature de la<br />transition métal-isolant. Il a été nécessaire de développer un<br />détecteur d'électrons. La réalisation de cet instrument s'est révélé<br />un défi du point de vue technique et il a demandé une quantité de<br />travail aussi bien sur la plan pratique que théorique. Les mesures<br />d'absorption de rayon-X ont été effectuées à la ligne de lumière<br />italienne pour la diffraction et l'absorption (GILDA-BM8) à<br />l'Installation Européenne de Rayonnement de Synchrotron (ESRF) de<br />Grenoble (France).

Ferroelectric materials have received lots of attention thanks to their intriguing properties such as the piezoelectric and pyroelectric effects, as well as the large dielectric constants and the spontaneous polarization which can potentially be used for information storage. In particular, perovskite crystal has a very simple unit cell structure yet a very rich phase transition diagram, which makes it one of the most intensively studied ferroelectric materials. In this dissertation, we use effective Hamiltonian, a first-principles-based computational technique to study the finite-temperature properties of ferroelectric perovskites. We studied temperature-graded (BaxSr1-x )TiO3 (BST) bulk alloys as well as the dynamics of nanodomain walls (nanowalls) in Pb(ZrxTi1-x )O3 (PZT) ultra-thin films under the driving force of an AC field. Our computations suggest that, for the temperature-graded BST, the polarization responds to the temperature gradient (TG), with the "up" and "down" offset observed in polarization components along the direction of TG, in agreement with the findings from experiments. For the nanowalls in PZT, the dynamics can be described by the damped-harmonic-oscillator model, and we observed a size-driven transition from resonance to relaxational dynamics at a critical thickness of 7.2 nm. The transition originates from the change in the effective mass of a nanowall as a film thickness increases. Some of the findings may find potential applications in various devices, such as thermal sensors, energy converters, or novel memory units.

This thesis primarily focuses on the systematic understanding of structure – reactivity relationships in two representative systems: bixbyite and related structures as well as indium doped CeO2. Topotactic reaction routes have gained significant attention over the past two decades due to their potential to access kinetically controlled metastable materials. This has contributed substantially to the understanding of solid state reaction pathways and provided first insights into mechanisms. Contrary to the widely used ex-situ methods, in – situ techniques including powder x-ray diffraction and thermogravimetric – differential thermal analysis have been employed extensively throughout this work in order to follow the reaction pathways in real time. Detailed analysis of the AVO3 (A = In, Sc) bixbyite reactivity under oxidative conditions has been carried out and a variety of novel metastable oxygen defect phases have been identified and characterized. The novel metastable materials have oxygen deficient fluorite structures and consequently are potential ion conductors. Structural aspects of the topotactic vs. reconstructive transformations are illustrated with this model system. The structure – reactivity study of AVO3 phases was extended to AVO3 perovskite family. Based on the research methodologies and results from AVO3 bixbyite reactivity studies a generalized mechanistic oxidation pathway has been established with a non-vanadium phase, ScTiO3 bixbyite. However, there is stark contrast in terms of structural stability and features beyond this stability limit during AVO3 and ScTiO3 bixbyite reaction pathways. A series of complex reaction sequences including phase separation and phase transitions were identified during the investigation of ScTiO3 reactivity. The two-step formation pathway for the fluorite – type oxide ion conductor Ce1-xInxO2-δ (0 ≤ x ≤ 0.3) is being reported. The formation of the BaCe1-xInxO3-δ perovskites and the subsequent CO2-capture reaction with the formation of Ce1-xInxO2-δ (0 ≤ x ≤ 0.3) has been investigated in detail. The two-step formation pathway is contrasted with the unsuccessful direct method. The stability and the extent of In – doping for the CeO2 fluorite phases that can be achieved through this CO2 – capture method are reported. The necessity and strategies for the selection of appropriate intermediate precursors for the preparation of doped CeO2 are also reported.

Doctor of Philosophy(PhD) / This project focuses on the examination of the structures of lanthanide containing double perovskites of the type Ba2LnB'O6-d (Ln = lanthanide or Y3+ and B' = Nb5+, Ta5+, Sb5+ and/or Sn4+) using synchrotron X-ray and neutron powder diffraction. The first part of this project examined the relative stability of R3 rhombohedral and I4/m tetragonal structures as the intermediate phase adopted by the series Ba2LnB'O6 (Ln = lanthanide (III) or Y3+ and B' = Nb5+, Ta5+ or Sb5+). It was found that I4/m tetragonal symmetry was favoured when B' was a transition metal with a small number of d electrons, such as Nb5+ or Ta5+. This is due to the presence of p-bonding in these compounds. In the Ba2LnNbO6 and Ba2LnTaO6 series R3 rhombohedral symmetry was, however, favoured over I4/m tetragonal symmetry when Ln = La3+ or Pr3+ due to the larger ionic radius of these cations. The incompatibility of the d0 and d10 B'-site cations in this family of compounds was indicated by significant regions of phase segregation in the two series Ba2Eu1-xPrxNb1-xSbxO6 and Ba2NdNb1-xSbxO6. In the second part of this project the compounds in the series Ba2LnSnxB'1-xO6-d (Ln = Pr, Nd or Tb and B' = Nb5+ or Sb5+) were examined to understand the relative stability of oxygen vacancies in these materials compared to the oxidation of the lanthanide cations and to determine if any oxygen vacancy ordering occurred. It was found, using a combination of structural characterisation, X ray Absorption Near Edge Structure and Ultra-Violet, Visible and Near Infrared spectroscopies, that with Ln = Pr or Tb increased Sn4+ doping results in a change in the oxidation state of the Ln3+ cations to Ln4+. This leads to those series containing little or no oxygen vacancies. A loss of B site cation ordering was found to accompany this oxidation state change and phase segregation was found to occur in the Ba2PrSnxSb1-xO6-d series most likely due to the Pr3+ and Pr4+ cations segregating into different phases. The Nd3+ cations in the series Ba2NdSnxSb1-xO6-d, however, can not oxidise to the tetravalent state so the number of oxygen vacancies rises with increasing x. It was found that oxygen vacancies concentrate onto the axial site of the compounds with x = 0.6 and 0.8 at ambient temperature. In Ba2Sn0.6Sb0.4O5.7 the oxygen vacancies were found to change to concentrating on the equatorial site at higher temperatures and it is suggested that this oxygen vacancy ordering plays a role in the adoption of I2/m monoclinic symmetry.

abstract: Fluids such as steam, oils, and molten salts are commonly used to store and transfer heat in a concentrating solar power (CSP) system. Metal oxide materials have received increasing attention for their reversible reduction-oxidation (redox) reaction that permits receiving, storing, and releasing energy through sensible and chemical potential. This study investigates the performance of a 111.7 MWe CSP system coupled with a thermochemical energy storage system (TCES) that uses a redox active metal oxide acting as the heat transfer fluid. A one-dimensional thermodynamic model is introduced for the novel CSP system design, with detailed designs of the underlying nine components developed from first principles and empirical data of the heat transfer media. The model is used to (a) size components, (b) examine intraday operational behaviors of the system against varying solar insolation, (c) calculate annual productivity and performance characteristics over a simulated year, and (d) evaluate factors that affect system performance using sensitivity analysis. Time series simulations use hourly direct normal irradiance (DNI) data for Barstow, California, USA. The nominal system design uses a solar multiple of 1.8 with a storage capacity of six hours for off-sun power generation. The mass of particles to achieve six hours of storage weighs 5,140 metric tonnes. Capacity factor increases by 3.55% for an increase in storage capacity to eight hours which requires an increase in storage volume by 33% or 737 m3, or plant design can be improved by decreasing solar multiple to 1.6 to increase the ratio of annual capacity factor to solar multiple. The solar reduction receiver is the focal point for the concentrated solar energy for inducing an endothermic reaction in the particles under low partial pressure of oxygen, and the reoxidation reactor induces the opposite exothermic reaction by mixing the particles with air to power an air Brayton engine. Stream flow data indicate the solar receiver experiences the largest thermal loss of any component, excluding the solar field. Design and sensitivity analysis of thermal insulation layers for the solar receiver show that additional RSLE-57 insulation material achieves the greatest increase in energetic efficiency of the five materials investigated. / Dissertation/Thesis / Masters Thesis Civil and Environmental Engineering 2017

Made available in DSpace on 2014-06-11T19:27:25Z (GMT). No. of bitstreams: 0 Previous issue date: 2006-11-10Bitstream added on 2014-06-13T20:56:28Z : No. of bitstreams: 1 tonelli_mc_me_bauru.pdf: 656379 bytes, checksum: 088ba2edc1bcc1ff564c0ee2c5f19b27 (MD5) / Secretaria de Educação do Estado de São Paulo / Neste trabalho foram realizados cálculos mecânico-quânticos periódicos, efetuados em nível ab initio e utilizando-se a teoria do funcional da densidade, combinada com dois diferentes funcionais híbridos: B3LYP e B3PW para dois tipos de peroviskitas de grande interesse tecnológico: BaZrO.3 e BaTiO.3. A simulação de modelos periódicos foi empregada para fazer um estudo sistemático das propriedades estruturais, eletrônicas e mecânicas com a finalidade de validar a metodologia aplicada, assim como o modelo proposto que inclui o nível de teoria aplicado e o conjunto de funções de base que descrevem matematicamente através de funções os orbitais atômicos. Com o objetivo de confrontar os resultados obtidos a partir da implementação do modelo com outros estudos teóricos e experimentais, foram analisadas as densidades de estados, estrutura de bandas e diagrama de energia. Esse estudo teórico possibilitou a identificação dos átomos que mais contribuem para as bandas de energia e também as energias na região entre os limites superiores da banda de valência e inferiores da banda de condução. / We used quantum-mechanical calculations at the Density Functional Theory level, applying periodical models with the B3LYP and B3PW methods to study two systems of technological interest: BaZrO.3 e BaTiO.3. The simulation of periodical models was used to perform a systematical study of the structural, electronic and mechanical properties of those materials with the aim to validate the applied methodology, the proposed model, the level of theory and the base functions that described the atomic orbital mathematically. The objective was to compare the results obtained using the methodology of the present work with the others methodologies utilized in another experimental as theoretical studies. We analyzed the density of states and the band structures and compared with results of others methodologies of study. From the results obtained in the present work could identify whose atoms can make the major contribution to the energy bands near the Fermi level and close to conduction band.

Made available in DSpace on 2016-06-02T19:55:42Z (GMT). No. of bitstreams: 1 6404.pdf: 6288273 bytes, checksum: f141c2e0ebc71d3e9e5003320f139929 (MD5) Previous issue date: 2014-07-30 / Financiadora de Estudos e Projetos / The hydrogen production has been extensively studied as a clean and powerful energy source, indicating that in the future hydrogen will became a key component for the global energy production, since burning fossil fuels, used nowadays, emits disturbing amounts of gases that cause the greenhouse effect and the global warming, which urgently needs to be reduced. Thus, hydrogen use has been studied as electric power generation and as a fuel derived from, for example, fuel cells that are able to convert chemical energy from the reaction between H2 and O2 into electrical energy, thermal energy and water, without causing environmental impacts, since it has no noises or vibrations and there is neither combustion or emission of particulates. A feasible way to produce hydrogen is the Steam Reforming Reaction of ethanol, since ethanol is a renewable source obtained mainly from sugar cane and also due to the low costs of operation in the Steam Reforming Reaction. Due to these facts, the reactions of Steam Reforming of Ethanol (SRE) have been extensively studied in previous years, and several studies have shown that this reaction provides a high hydrogen production; however, some parallel reactions may occur, forming side products, leading to reduced amounts of produced H2. Thus, the development of appropriate catalysts in these reactions becomes necessary, in a way that it enhances the conversion favoring the major product and suppressing the conversion to side products. A good efficiency of perovskite type oxides as catalysts in the SRE has been reported in several studies. These materials are mixed oxides with an ABO3 chemical structure, A being the largest cation such as alkali metals, alkaline earth metals and rare earth elements, and B representing the smallest cation such as transition metals. The partial substitution of cations located in the B site by others with similar oxidation state can promote changes in the redox properties of these ions, causing changes in the stability of the crystal structure. Therefore, the perovskite type oxides LaNiO3, LaCoO3 and LaFeO3 were synthesized through the citrate and precipitation methods. In a second stage Fe was added into the structure of the oxides LaNiO3 and LaCoO3, and in a new stage LaNiO3, LaCoO3 and LaFeO3 was synthesized with perovskite type oxides supported on gamma alumina by precipitation-deposition. After the syntheses, the catalysts were characterized and the influence of the preparation method was studied, specifically the effect of Fe addition and of the support presence, in relation to the activity of the catalysts in the reactions of steam reforming of ethanol for hydrogen production. The experimental results showed that the LaCoO3 catalyst synthesized by precipitation method was more active and stable than the others, although the LaNiO3 (citrate and precipitation) and LaCoO3 (citrate) catalysts had also been active in SRE. The material LaFeO3 showed to be inactive in the reaction. The Fe addition in the catalysts LaNiO3 and LaCoO3 structure did not significantly alter their catalytic performance, indicating an economically advantageous feature, since iron is a cheaper metal than cobalt and nickel, and may partially replace these elements in the catalyst formulation, thus decreasing the synthesis cost without compromising the hydrogen yields. The use of gamma alumina as support in the SRE favored materials with higher specific surface area, whereas it did not favor a higher activity or stability of these catalysts, however the activity was maintained. / A produção de hidrogênio tem sido bastante estudada como fonte de energia não poluente e potente, indicando que futuramente este será componente fundamental para a produção mundial de energia, já que a queima de combustíveis fósseis, utilizada nos dias atuais, emite uma preocupante quantidade de gases causadores do efeito estufa e aquecimento global, que precisam urgentemente ser reduzidos. Assim, tem sido estudada a utilização de hidrogênio na geração de energia elétrica e como combustível veicular, a partir, por exemplo, da célula a combustível, que converte a energia química proveniente da reação entre H2 e O2 em energia elétrica, energia térmica e água, sem causar impactos ambientais já que não apresenta ruídos, vibrações, não ocorre combustão e não são emitidos particulados. Uma forma de produção do hidrogênio viável é a reação de reforma a vapor do etanol, pelo fato deste álcool ser um composto renovável proveniente principalmente da cana de açúcar e também devido à reação de reforma oferecer um baixo custo operacional. A partir destes fatos, as reações de reforma a vapor do etanol (RVE) têm sido extensivamente estudadas nos últimos anos e vários estudos mostram que esta possibilita uma elevada produção de hidrogênio. No entanto, podem ocorrer algumas reações paralelas com formação de subprodutos, provocando a diminuição da quantidade de H2 produzido. Assim torna-se necessário o desenvolvimento de catalisadores apropriados para estas reações, que favoreçam a conversão ao produto principal e suprimam a formação de subprodutos indesejados. Tem sido reportada em diversos estudos a boa eficiência de óxidos do tipo perovskita como catalisadores para a RVE. Estes são óxidos mistos com estrutura química ABO3, sendo A um cátion grande tal como os metais alcalinos, os alcalinos terrosos e os elementos terras raras e B um cátion menor, tal como um metal de transição. A substituição parcial de cátions do sítio B por outros de número de oxidação semelhante pode promover mudanças nas propriedades redox dos íons, provocando alterações na estabilidade da estrutura cristalina. Deste modo, neste trabalho, óxidos tipo pervskita LaNiO3, LaCoO3 e LaFeO3, foram sintetizados através dos métodos citrato e de precipitação. Em uma segunda etapa do trabalho adicionou-se Fe na estrutura dos óxidos LaNiO3 e LaCoO3 e em uma nova etapa sintetizou-se, por precipitação-deposição, óxidos do tipo pervskita LaNiO3, LaCoO3 e LaFeO3 suportados em gama-alumina. Após as sínteses, os catalisadores foram caracterizados e foram realizados estudos da influência dos métodos de preparação, do efeito da adição de ferro e da presença do suporte, na atividade dos catalisadores nas reações de reforma a vapor de etanol para produção de hidrogênio. Os resultados experimentais mostraram que o catalisador LaCoO3 sintetizado pelo método de precipitação se apresentou mais ativo e estável que os demais, embora os catalisadores LaNiO3 (citrato e precipitação) e LaCoO3 (citrato) também tenham sido ativos na RVE. Já o composto LaFeO3 não mostrou atividade na reação. A inserção de Fe na constituição dos catalisadores LaNiO3 e LaCoO3 não alterou significativamente suas eficiências, sugerindo uma característica economicamente vantajosa, já que o ferro é um componente de menor custo que cobalto e níquel, podendo substituir parcialmente estes elementos na formulação do catalisador, diminuindo seu custo de síntese sem comprometer o rendimento a hidrogênio. O estudo do suporte na RVE mostrou que a utilização de gama-alumina resultou em aumento da área específica mas não levou a uma maior atividade ou estabilidade dos catalisadores, no entanto manteve sua atividade.

Resumo: Neste trabalho foram realizados cálculos mecânico-quânticos periódicos, efetuados em nível ab initio e utilizando-se a teoria do funcional da densidade, combinada com dois diferentes funcionais híbridos: B3LYP e B3PW para dois tipos de peroviskitas de grande interesse tecnológico: BaZrO.3 e BaTiO.3. A simulação de modelos periódicos foi empregada para fazer um estudo sistemático das propriedades estruturais, eletrônicas e mecânicas com a finalidade de validar a metodologia aplicada, assim como o modelo proposto que inclui o nível de teoria aplicado e o conjunto de funções de base que descrevem matematicamente através de funções os orbitais atômicos. Com o objetivo de confrontar os resultados obtidos a partir da implementação do modelo com outros estudos teóricos e experimentais, foram analisadas as densidades de estados, estrutura de bandas e diagrama de energia. Esse estudo teórico possibilitou a identificação dos átomos que mais contribuem para as bandas de energia e também as energias na região entre os limites superiores da banda de valência e inferiores da banda de condução. / Abstract: We used quantum-mechanical calculations at the Density Functional Theory level, applying periodical models with the B3LYP and B3PW methods to study two systems of technological interest: BaZrO.3 e BaTiO.3. The simulation of periodical models was used to perform a systematical study of the structural, electronic and mechanical properties of those materials with the aim to validate the applied methodology, the proposed model, the level of theory and the base functions that described the atomic orbital mathematically. The objective was to compare the results obtained using the methodology of the present work with the others methodologies utilized in another experimental as theoretical studies. We analyzed the density of states and the band structures and compared with results of others methodologies of study. From the results obtained in the present work could identify whose atoms can make the major contribution to the energy bands near the Fermi level and close to conduction band. / Orientador: Aguinaldo Robinson de Souza / Coorientador: Julio Ricardo Sambrano / Banca: Sergio Ricardo de Lazaro / Banca: Ignez Caracelli / O Programa de Pós-Graduação em Ciência e Tecnologia de Materiais, PosMat, tem caráter institucional e integra as atividades de pesquisa em materiais de diversos campi da Unesp / Mestre

Submitted by Fabio Sobreira Campos da Costa (fabio.sobreira@ufpe.br) on 2017-02-06T17:05:22Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Mylena Pinto Nascimento - Mestrado em Física - 2010.pdf: 26227873 bytes, checksum: 74d40caac3d585dfb4d76146eb00d921 (MD5) / Made available in DSpace on 2017-02-06T17:05:22Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Mylena Pinto Nascimento - Mestrado em Física - 2010.pdf: 26227873 bytes, checksum: 74d40caac3d585dfb4d76146eb00d921 (MD5) Previous issue date: 2010-11-23 / CAPES / CNPq / Esse trabalho apresenta a produção e caracterização estrutural e morfológica das perovskitas simples TRFeO3 (TR = Sm, Eu, Gd), e o estudo da possibilidade de utilização desses sistemas como sensores de gás. Todas as amostras de TRFeO3 foram produzidas pela síntese de reação no estado sólido, que é uma síntese ainda pouco explorada na literatura para a obtenção desse sistema. O estudo das propriedades estruturais foram realizados por difração de raios X e adsorção e dessorção de N2, e a análise morfológica foi realizada através da microscopia eletrônica de varredura (MEV). Todas essas análises foram estudadas em função da temperatura e tempo de sinterização, bem como do cátion da terra rara utilizada. Através das análises por difratometria, foi possível a identificação da fase formada e a estimativa do tamanho médio do cristalito. Tais análises revelaram coexistência de fase com o composto TR3Fe5O12 para amostras sinterizadas a 1200°C, independente do tempo de sinterização utilizado, onde houve uma tendência a um equilíbrio na formação das fases. Já as amostras sinterizadas a 1100°C apresentaram-se monofásicas com o composto TRFeO3, com tamanho de cristalito variando conforme o tempo de sinterização. As imagens de MEV mostraram uma morfologia porosa, adequada para sensores de gás, apresentando grãos com formatos arredondados e formação de pescoço, conforme o tempo de sinterização utilizado. Independente da temperatura e tempo de sinterização, o tamanho dos grãos variaram em torno de 1 mm. Para avaliar a sensibilidade aos vapores de gasolina, foi desenvolvido um sistema baseado em medidas de resistividade elétrica, usando o método de 4-fios de Kelvin. Os resultados revelaram que um mecanismo diferente da literatura, onde a resistividade do material diminuiu quando exposto à atmosfera da mistura ar sintético/gasolina, a partir da temperatura ambiente, com boa reprodutibilidade. Através da dinâmica de tempo de resposta, em alta concentração de vapor do combustível utilizado, foi verificado que a capacidade sensorial dos compostos estudados, possivelmente, possui uma limitação com relação aos parâmetros estruturais, já que ambas propriedades estão relacionadas. Essa observação foi comprovada através do estudo realizado pelas medidas de adsorção e dessorção de N2, onde a área superficial das amostras foi em torno de 1,8 m2/g, o que diminui, significantemente, a sensibilidade. / This paper presents the production and structural and morphological characterization of simple perovskites REFeO3 (RE = Sm, Eu, Gd), and the possibility of using such systems as gas sensors. All REFeO3 samples were produced by the synthesis of solid state reaction, which is still little explored in the literature to obtain this system. The study of structural properties were carried out by X-ray diffraction and N2 adsorption and desorption, and the morphological analysis by scanning electron microscopy (SEM). All these tests were studied as a function of temperature and sintering time, and the rare earth cation used. Through this analysis by diffraction was possible to identify the phase formed and the estimated average size of crystallite. Such analysis revealed the coexistence of phase with the compound RE3Fe5O12 for samples sintered at 1200°C, regardless of time of sintering, where there was a tendency to an equilibrium in the formation stage. The samples sintered at 1100°C were presented with the monophasic compound REFeO3, with crystallite size varying according to the sintering time. The SEM images showed a porous morphology, suitable for gas sensors, showing grains with rounded shapes and neck formation, in accordance with the sintering time used. The grain size varied around 1 mm independent of temperature and sintering time. A system based on measurements of electrical resistivity, using the method of 4-wire Kelvin, was developed to detect the sensitivity to the vapors of gasoline. The results revealed that a different mechanism from literature, where the resistivity of the material decreased when exposed to atmospheric mixing synthetic air/gasoline from the ambient temperature, with good reproducibility. Through the dynamic response time, at high concentration of gasoline vapor, it was found that the sensory ability of the compounds studied, possibly, has a limitation with respect to structural parameters, since both properties are related. This observation was confirmed by the study performed by the measures of the adsorption and desorption of N2, where the surface area of the samples was about 1.8 m2/g, which decreases significantly the sensitivity.