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
| Identifer | oai:union.ndltd.org:IBICT/oai:repositorio.ufrn.br:123456789/18557 |
| Date | 27 December 2012 |
| Creators | Passos, Rafael Hernandez Damascena dos |
| Contributors | CPF:13681389420, http://buscatextual.cnpq.br/buscatextual/visualizacv.do?id=K4781094H3, Santos, Andarair Gomes dos, CPF:02813010421, http://lattes.cnpq.br/3470634368296605, Silva, Gilson Garcia da, CPF:56634161453, http://lattes.cnpq.br/8681275097040450, Souza, Carlson Pereira de |
| Publisher | Universidade Federal do Rio Grande do Norte, Programa de P?s-Gradua??o em Engenharia Qu?mica, UFRN, BR, Pesquisa e Desenvolvimento de Tecnologias Regionais |
| Source Sets | IBICT Brazilian ETDs |
| Language | Portuguese |
| Detected Language | English |
| Type | info:eu-repo/semantics/publishedVersion, info:eu-repo/semantics/masterThesis |
| Format | application/pdf |
| Source | reponame:Repositório Institucional da UFRN, instname:Universidade Federal do Rio Grande do Norte, instacron:UFRN |
| Rights | info:eu-repo/semantics/openAccess |
Page generated in 0.0025 seconds