BaO-Fe_2O_3系ガラスの熱処理によるESRならびにメスバウアースペクトルの変化(<小特集>セラミック材料)

概要

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0.6 Ba0-0.4 Fe_20_3 glass was prepared by twin-roller quenching method and its heat treatment process was examined by ESR and M6ssbauer spectroscopy. Fe^<3+> ions were found to occupy distorted tetrahedral sites in this glass. BaFe_2O_4 and Ba_2Fe_2O_5 were precipitated through the heat treatment at a temperature of 440℃. The former is an antiferromagnetic crystal having N6el temperature of 880K. Before the crystallization occurred, the linewidth of ESR spectrum decreased monotonously although neither isomer shift nor quadrupole splitting changed. It was considered that in this region Fe^<3+>-02---Fe^<3+> bond angle dominantly changed as a result of thermal relaxation of structure. When the crystallization occurred, both isomer shift and quadrupole splitting decreased significantly. These facts indicated that Fe^<3+>-O^<2-^> distance was longer in the glass than in the precipitated crystals and that the coordination state of O^<2-^> ions around Fe^<3+> was more distorted in the glass. Hyperfine field increased with increasing heat treatment temperature. This phenomenon was explained by considering the size of crystallized BaFe_2O_4 particles.
社団法人日本材料学会の論文
1987-01-15