Magnetic structure of as-quenched silicate glasses containing iron oxides

The effect of valence states of iron on the magnetic structure of as-quenched silicate glasses containing iron oxides has been investigated. The glasses, all having the same compositions, are melted in various oxygen pressures to control the ratios of Fe3+ ions to the total number of iron ions and quenched at the same speed, and the magnetic properties are measured. There are only a few reports which focus particularly on the relation between valence states of iron and the magnetic properties of the glasses. Here, the dc magnetizations and ac susceptibilities of the glasses are explained based upon a proposed magnetic structure model in which both microcrystalline clusters and free iron ions in the glass matrix bear magnetism. (In this article free iron ions mean iron ions which are distributed in the glass matrix. ) The number density of microcrystalline clusters is highest in a sample of x = 0.73 (x: the ratio of Fe3+ ions to the total number of iron ions! and it becomes smaller as the value of x becomes smaller and larger than 0.73. The average magnetic interaction among free iron ions in the glass matrix is stronger in the samples having larger values of x. (C) 1999 American Institute of Physics. [S002-18979(99)06904-2].