Low-temperature sintering of Z-type hexagonal ferrite by addition of fluorine containing glass powder

In order to reduce the sintering temperature of Ba3CO2Fe24O41 (CO(2)Z), fluorine containing glass powder was added as a sintering aid to ferrite powder with a CO(2)Z stoichiometric composition prepared by a solid-state reaction, and dense sintered specimens could be obtained at 1000degreesC in air. The densification was achieved by liquid-phase sintering which was induced by the melting of the additive glass at similar to800degreesC. The main crystalline phase was CO(2)Z, and spinel ferrite appeared as the impurity phase. By sintering in a sealed container, the densification was accelerated still more, and in addition to spinel ferrite, Ba-M also appeared as the impurity phase. The Ba-M contained some Co instead of Fe, and grew to discontinuously large hexagonal plate-like grains. In a fluorine and/or fluorides rich atmosphere, CO(2)Z was discomposed to Ba-M and spinel ferrite, and large hexagonal plate-like grains appeared. These results suggest that fluorine and/or fluorides evaporated from the additive glass decomposed CO(2)Z to Ba-M and spinel ferrite, and induced the discontinuously grain growth of Ba-M. The initial permeability was lower than that of the specimen with no additive glass but remained almost constant in the frequency regions up to 1 GHz. (C) 2005 Springer Science + Business Media, Inc.