Comparison of microwave and conventional processing of Ni-Fe manganites

摘要

Microwave and conventional processing have been compared in several papers and they have claim that there is a "Microwave effect" which enhance reaction rates. It has been theorized that activation energy is decreased during microwave processing and in turn reactions are faster, while other researches proposed that the pre-exponential factor in an Arrhenius equation is the only one that is affecting the reaction rate. In this work such comparison has been performed for sintering of Ni-Fe manganites, seeking for a reaction rate change and then conduct a research for proposing a mechanism that might explain this behavior. Fe was added to the manganites and compositions ranged from Ni{sub}0.6Mn{sub}2.4O{sub}4 to Fe{sub}0.7Ni{sub}0.62Mn{sub}1.68O{sub}4. Microwave processing was conducted at 2.45 GHz with graphite as thermal auxiliary. X-ray diffraction and density tests were conducted over the samples for determining sintering accomplishment. Phase transformation provides evidence of different reactions taking place.