Abstract
A microstructure of YIG sintered ferrites are examined for the starting contents of Fe2O3 for its fabrications. For the higher Fe2O3 content in YIG single-phase range, the densification starts at the lower temperatures, then the grain growth is accelerated at high temperatures. In air atmosphere, it can occur at the lower temperatures, as compared with in oxygen atmosphere. As a result, many pores can be observed in YIG ferrites with high Fe2O3 contents sintered in air atmosphere. Further a small amount of Fe2+ ions is detected in sintered YIG ferrites, that is slightly large for the higher Fe2O3 content, or/and the lower oxygen partial pressure or/and the longer sintering time. Eventually the grain growth behavior of YIG ferrites can be considered to be closely related to the formation of ferrous ions in them.
