Papers by Author: Ana Cristina F. Melo Costa

Abstract: The aim of this study is to evaluate the effect of temperature during the synthesis of alumina by combustion in a muffle furnace. The alumina was characterized by X-ray diffraction, particles size distribution and scanning electron microscopy. The results showed that the synthesis temperature of the alumina can affect the structure of the produced samples. The size distribution of the median particle diameter reached higher value for the alumina synthesized at 500°C with 16.07 μm, the range of the total distribution of particles is introduced to the large alumina synthesized 500 and 600°C and close synthesized when 700 and 800°C. The phase of the alumina was identified only after the synthesized sample at 800°C with crystallite size of 22.16 and 6.75 μm synthesized samples 800 and 900°C, respectively. With respect to morphology, increased synthesis temperature was not enough to significantly change.

Abstract: The search of variations in the methodology for obtaining nanoferrites has attracted the interest of researchers in search of better results with regard to the structure and morphology of these materials. This study evaluates the effect of microwave power (50 and 70 W) in the structural and morphological characteristics of NiZn ferrite, using aniline as a fuel for combustion reaction. The aluminas were characterized by X-ray diffraction and scanning electron microscopy. The results showed that only the variation in microwave power is sufficient to change the structure of nanoferrites. The sample synthesized in power of 50 W was presented monophasic, illustrating the ferrite phase with crystallite size of 50.04 nm; and for 70 W, it was appeared, besides the ferrite phase, hematite and zinc oxide with a crystallite size of 17.07 nm. The morphology did not change significantly, the nanoferrites showed particles with similar geometry.