硫酸イオンがMnZnフェライトの粒界構造に及ぼす影響

概要

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The effect in MnZn ferrite of sulphate ion on grain boundary chemistry and core loss was studied. When MnZn ferrite powder with additives (SiO_2, CaCO_3) is milled in water, CaSO_4. 1/2 H_2O forms from a sulphate ion impurity and the added CaCO_3.In the case of sintered specimens of powder rich in sulphate ion content, Ca is not located uniformly along the grain boundary. These specimens have relatively higher coercive force, lower electric resistivity, and in consequence, higher core loss. In MnZn ferrite, it is well known that the grain boundary chemistry depends heavily on phase equilibria of the CaO-SiO_2-Fe_2O_3 system. Termogravimetry data show that it is very hard to decompose CaSO_4 into CaO and SO_3. We consider that the formation of CaSO_4 prevents the uniform spread of Ca along the grain boundary in MnZn ferrite at sintering.
社団法人日本磁気学会の論文
2000-04-15