Made available in DSpace on 2014-12-17T15:01:25Z (GMT). No. of bitstreams: 1 MaxwellF_DISSERT.pdf: 5002328 bytes, checksum: 0f37f8be5c901a29ea1ab20a58f7143c (MD5) Previous issue date: 2011-03-18 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / In this study, binary perovskite (BaCexO3) were doped with praseodymium (Pr) to obtainment of the ternary material BaCexPr1-xO3. This material was synthesized by the complexation method combining EDTA/Citrate with the stoichiometric ratio of the element Praseodymium ranging from x = 0.1 to x = 0.9 in order to determine the influence of this rare earth element on the morphology and microstructure of the final powder. At first the material was synthesized based on the route proposed by literature (Santos, 2010), and then characterized by SEM and XRD, besides being refined by the Rietveld method. In the material that had lowest residual parameter, S, and lowest average size of crystal, pH variation of synthesis solution was made in order to identify the influence of this parameter on the morphology and microscopy of the final powder. The results show that addition of praseodymium did not directly influence the crystallographic and lattice parameters, keeping even the same orthorhombic structure of the binary material BaCexO3, according to Yamanaka et al (2003). Material type BaCe0,2Pr0,8O3 had lowest residual parameter (S=1.4) and lowest average size of crystallite (26.4 nm), being used as reference in the pH variation of synthesis solution for 9, 7, 5 and 3, respectively. Variation of this parameter showed that when the synthesis solution pH was decreased to below 11, there was an increase in the average size of crystals, for pH 9, about 58.3%, for pH 7 (30.3 %), for pH 2 (2.3%) and for pH 3 (42%), indicating that the value initially used and quoted by Santos (2010) was the most coherent / No presente trabalho, perovskitas bin?rias do tipo (BaCexO3) foram dopadas com praseod?mio (Pr) para obten??o de materiais tern?rios do tipo BaCexPr1-xO3. Esse material foi sintetizado pelo m?todo de complexa??o combinando EDTA/Citrato, com a raz?o estequiom?trica do elemento praseod?mio variando de x=0,1 a x=0,9, com objetivo de determinar a influ?ncia deste terra rara na morfologia e microestrutura do p? final. Em principio o material foi sintetizado com base em rota proposta na literatura (Santos, 2010), sendo em seguida caracterizado via MEV e DRX, al?m de serem refinados pelo m?todo Rietveld. No material que obteve menor par?metro residual, S, e menor tamanho m?dio de cristal foi feita a varia??o do pH da solu??o de s?ntese a fim de identificar a influ?ncia deste par?metro na morfologia e microscopia do p? final. Os resultados mostram que a adi??o do elemento praseod?mio n?o influenciou diretamente os par?metros cristalogr?ficos e de rede, mantendo, inclusive, a mesma estrutura ortorr?mbica do material bin?rio do tipo BaCexO3, de acordo com Yamanaka et al (2003). O material do tipo BaCe0,2Pr0,8O3 obteve menor par?metro residual (S=1,4) e menor tamanho m?dio de cristalito (26,4 nm), sendo usado como refer?ncia na varia??o do pH da solu??o de s?ntese para 9, 7, 5 e 3, respectivamente. A varia??o desse par?metro mostrou que quando foi diminu?do o pH da solu??o de s?ntese para valores abaixo de 11, houve um aumento no tamanho m?dio dos cristais, para o pH 9, em torno de 58,3 %, para o pH7 (30,3%), para o pH2 (2,3%) e para o pH3 (42%), indicando que o pH 11 utilizado inicialmente e citado por Santos (2010) foi o mais coerente