Made available in DSpace on 2014-12-17T15:01:34Z (GMT). No. of bitstreams: 1 IndiraAFM_DISSERT_Parcial.pdf: 1021016 bytes, checksum: 339ff82fc9edc8d5f827859010abd0dc (MD5) Previous issue date: 2013-12-17 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / In this work it was synthesized and characterized the cobalt ferrite (CoFe2O4) by two methods: complexation combining EDTA/Citrate and hydrothermal investigating the influence of the synthesis conditions on phase formation and on the crystallite size. The powders were mainly characterized by x-ray diffraction. In specific cases, it was also used scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), x-ray fluorescence (XRF) and isotherms of adsorption and desorption of nitrogen (BET method). The study of the crystallite size was based on the interpretation of x-ray diffractograms obtained and estimated by the method of Halder-Wagner-Scherrer and Langford. An experimental design was made in order to assist in quantifying the influence of synthesis conditions on the response variables. The synthesis parameters evaluated in this study were: pH of the reaction medium (8, 9 and 10), the calcination temperature (combined complexation method EDTA/Citrate 600?C, 800?C and 1000?C), synthesis temperature (hydrothermal method 120?C, 140?C and 160?C), calcination time (combined complexation method EDTA/Citrate - 2, 4 and 6 hours) and time of synthesis (hydrothermal method 6, 15 and 24 hours). By the hydrothermal method was possible to produce mesoporous powders with high purity, with an average crystallite size up to 7 nm, with a surface area of 113.44 m?/g in the form of pellets with irregular morphology. By using the method of combined complexation EDTA/Citrate, mesoporous powders were produced with greater purity, crystallite size up to 22nm and 27.95 m?/g of surface area in the form of pellets with a regular morphology of plaques. In the experimental design was found that the hydrothermal method to all the studied parameters (pH, temperature and time) have significant effect on the crystallite size, while to the combined complexation method EDTA/Citrate, only temperature and time were significant / Neste trabalho foi sintetizada e caracterizada a ferrita de cobalto (CoFe2O4) atrav?s dos m?todos complexa??o combinada EDTA/Citrato e hidrot?rmico, investigando a influ?ncia das condi??es de s?ntese na forma??o da fase e no tamanho m?dio de cristalito. Os p?s foram caracterizados principalmente por difra??o de raios-x. Em casos espec?ficos, tamb?m foi utilizado microscopia eletr?nica de varredura (MEV), espectroscopia de energia dispersiva (EDS), fluoresc?ncia de raios-x (FRX) e isotermas de adsor??o e dessor??o de nitrog?nio (M?todo BET). O estudo do tamanho de cristalito foi baseado na interpreta??o dos difratogramas de raios-x obtidos e estimado atrav?s do m?todo de Halder-Wagner-Langford (HWL) e de Scherrer. Um planejamento experimental foi realizado com a finalidade de auxiliar na quantifica??o da influ?ncia das condi??es de s?ntese nas vari?veis-resposta. Os par?metros de s?ntese avaliados neste trabalho foram: pH do meio reacional (8, 9 e 10), temperatura de calcina??o (m?todo de complexa??o combinando EDTA/Citrato 600?C, 800?C e 1000?C), temperatura de s?ntese (m?todo hidrot?rmico 120?C, 140?C e 160?C), tempo de calcina??o (m?todo de complexa??o combinando EDTA/Citrato 2, 4 e 6 hrs) e tempo de s?ntese (m?todo hidrot?rmico 6, 15 e 24 hrs). Pelo m?todo hidrot?rmico foi poss?vel produzir p?s mesoporosos com elevado grau de pureza, com tamanho m?dio de cristalito de at? 7nm, com ?rea superficial de 113,44m?/g e na forma de aglomerados com morfologia irregular. Ao se utilizar o m?todo de complexa??o combinando EDTA/Citrato foram produzidos p?s mesoporosos com maior pureza, cristalitos com at? 22nm de tamanho, 27,95m?/g de ?rea superficial e na forma de aglomerados com morfologia regular de placas. No planejamento experimental foi constatado que no caso do m?todo hidrot?rmico todos os par?metros estudados (pH, Temperatura e tempo) apresentam efeito significativo no tamanho de cristalito, enquanto que, para o m?todo de complexa??o combinando EDTA/Citrato, apenas a temperatura e o tempo foram significativos / 2020-01-01