Role of Zinc Volatilization on the Microstructure Development of Manganese Zinc Ferrites

The role of Zn atmosphere on the microstructure development of Mn-Zn ferrite prepared by alcholic dehydration was investigated. Discontinuous grain growth and intragranular porosity were observed throughout the specimen when a low oxygen partial pressure was employed during sintering. The microstructure of Mn-Zn ferrite sintered in air resembled a mixture between Mn ferrite (uniform grain size) and Zn ferrite (exaggerated grain growth). Exaggerated grain growth was also observed on the surface of Mn ferrite sintered in the presence of a Zn-rich atmosphere. The presence of Zn vapor phase enhanced the grain growth kinetics. The overall results indicate that a strict control of atmosphere is required in order to achieve a uniform pore-free microstructure.