Resumo

PRIETO GARCIA, Francisco; RIVERA RAMIREZ, Euridice; MENDEZ MARZO, María  A  e  GORDILLO MARTINEZ, Alberto. Caracterización de ferritas de níquel obtenidas mediante mecanosíntesis. Rev. LatinAm. Metal. Mater. [online]. 2008, vol.28, n.2, pp.111-120. ISSN 0255-6952.

NiFe₂O₄ crystalline particles were synthesized by milling in a ball mill, from a stoichiometric mixture of NiO and α -Fe₂O₃. The mechanosynthesis process was carried out at room temperature using a steel container and steel balls, maintaining a 10:1 ball / dust size ratio. Further analysis of phases was performed on powders by both, X-ray diffraction and Rietveld´s method, the latter was used in order to study chemical transformations occurring within the system. The spinel phase of NiFe₂O₄ crystals started to appear after milling for 5 hours and increased up to its maximum composition level (78% w/w) detected between 7 to 9 hours of milling time. A longer period of milling time (more than 12 hours) caused a metallic iron contamination that was originated from inside the steel container, because of steel balls deterioration. It was also estimated the formation rate of nickel ferrites when using this method, which is about 0.067 g/h. The so obtained ferrites exhibited a magnetic permeability (µ_REL) of 58 kHz and an average particle size of 166 µm. Finally infrared spectroscopy (IR) and scanning electron microscopy (SEM) were performed, in order to characterise structure and morphology of products from the reaction.

Palavras-chave : Ferrite; Mechanical synthesis; Magnetic permeability; Rietveld method.