Made available in DSpace on 2015-03-03T15:01:58Z (GMT). No. of bitstreams: 1 RafaelHDP_DISSERT.pdf: 3336439 bytes, checksum: 4e38712624b4415413756d8862553f95 (MD5) Previous issue date: 2012-12-27 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico / Ceramic powders based on oxides of perovskite-type structure is of fundamental interest nowadays, since they have important ionic-electronic conductivity in the use of materials with technological applications such as gas sensors, oxygen permeation membranes, catalysts and electrolytes for solid oxide fuel cells (SOFC). The main objective of the project is to develop nanostructured ceramic compounds quaternary-based oxide Barium (Br), Strontium (Sr), Cobalt (Co) and Iron (Fe). In this project were synthesized compounds BaxSr(1-x)Co0, 8Fe0,2O3- (x = 0.2, 0.5 and 0.8) through the oxalate co-precipitation method. The synthesized powders were characterized by thermogravimetric analysis and differential thermal analysis (TGADTA), X-ray diffraction (XRD) with the Rietveld refinement using the software MAUD and scanning electron microscopy (SEM). The results showed that the synthesis technique used was suitable for production of nanostructured ceramic solid solutions. The powders obtained had a crystalline phase with perovskite-type structure. The TGA-DTA results showed that the homogeneous phase of interest was obtained temperature above 1034?C. It was also observed that the heating rate of the calcination process did not affect the elimination of impurities present in the ceramic powder. The variation in the addition of barium dopant promoted changes in the average crystallite size in the nanometer range, the composition being BSCF(5582) obtained the lowest value (179.0nm). The results obtained by oxalate co-precipitation method were compared with those synthesis methods in solid state and EDTA-citrate method / P?s cer?micos ? base de ?xidos de estrutura do tipo perovsquita ? de fundamental interesse atualmente, pois apresentam condutividade i?nica e eletr?nica importante na utiliza??o de materiais com aplica??es tecnol?gicas como: sensores de gases, membranas perme?veis ao oxig?nio, catalisadores e eletr?lito para c?lulas a combust?vel de ?xido s?lido . O objetivo principal dessa pesquisa ? desenvolver compostos cer?micos quarten?rios nanoestruturados ? base de ?xidos de B?rio (Br), Estr?ncio (Sr), Cobalto (Co) e Ferro (Fe). Nesse trabalho foram sintetizados compostos de BaxSr(1-x)Co0,8Fe0,2O3-(x = 0,2, 0,5 e 0,8) atrav?s do m?todo de coprecipita??o via oxalato. Os p?s sintetizados foram caracterizados por an?lise termogravim?trica e termodiferencial (TGA-TDA), difra??o de raios X (DRX) com refinamento pelo m?todo de Rietveld atrav?s do software MAUD e microscopia eletr?nica de varredura (MEV). Os resultados obtidos mostraram que a t?cnica de s?ntese utilizada foi satisfat?rio para produ??o de solu??es s?lidas cer?micas nanoestruturadas. Os p?s obtidos apresentaram uma fase cristalina com estrutura do tipo perovsquita. O resultado de TGA-DTA apresentou que a fase homog?nea de interesse foi obtida a temperatura acima de 1034?C. Foi observado tamb?m que a taxa de aquecimento do processo de calcina??o n?o interferiu na elimina??o das impurezas presentes no p? cer?mico. A varia??o na adi??o do dopante b?rio promoveu altera??es no tamanho m?dio de cristalito em escala nanom?trica, sendo a composi??o BSCF(5582) obtido o menor valor (179,0nm). Os resultados obtidos pelo m?todo de coprecipita??o foram comparados com os m?todos de s?ntese em estado s?lido e complexa??o EDTA-citrato