Magnetic Properties of EuO-Al₂O₃-B₂O₃-SiO₂ Glasses with High Eu²⁺ Concentration

Abstract

Fabrication of EuO-Al₂O₃-B₂O₃-SiO₂ glasses with high-concentration of Eu²⁺ ions was attempted in N₂ gas with an IR-image furnace and rapid quenching in twin rollers. Their magnetic susceptibilities of these glasses obeyed the Curie-Weiss law with the negative Curie temperature at temperatures higher than 50 K, while Eu²⁺ ions coupling by a superexchange-type mechanism involving oxygen ions at temperatures lower than 50 K showed a ferromagnetism. From their magnetization data at lower temperatures, we estimated an amount of Eu²⁺ ions in the glasses, in whose fabrication process a part of Eu²⁺ ions were oxidized to Eu³⁺. We also measured FT-IR and Raman spectra and discussed the stable valence state of europium ions in the studied glass-matrixes.