Navegando por Autor "Cunha, Jardel Dantas"

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Pechini synthesis and microstructure of nickel-doped copper chromites
(Scielo, 2005) Pimentel, Patrícia Mendonça; Martinelli, Antonio Eduardo; Melo, Dulce Maria de Araújo; Pedrosa, Anne Michelle Garrido; Cunha, Jardel Dantas; Silva Júnior, Carlos Neco da
Spinel-type solid solutions were synthesized by the Pechini method and calcined between 500 and 900 °C for 4 hours and at 900 °C for 8 hours to produce ceramic pigments. The resulting powders were characterized by thermogravimetric analysis, Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), particle size analysis and BET surface area measurements. The formation of spinel took place upon calcination at 700 °C. IR spectroscopy revealed the presence of N1 and N2 bands, typical of spinel structures, broadened by the presence of more than one cationic species in the structure. The specific area of the resulting powder decreased from 24.7 to 1.4 m2 g-1 as the calcination temperature increased from 700 to 900 °C. Microstructural analyses revealed the presence of crystalline spinel as the only phase present in powders calcined at 900 °C. Colorimetric analyses using L*a*b* coordinates and UV-visible spectroscopy revealed that the pigment was predominantly black

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