Nanocrystal Formation In Glasses Controlled By Rare Earth Ions

Distribution and roles of rare earth ions in fluoride nanocrystals and lead chalcogenide quantum dots formed in glasses are reported. High-resolution transmission electron microscopic analysis and electron energy loss spectroscopic (EELS) analysis showed that oxyfluoride glasses initially form crystals with high Er3+ content such as PbErF5 during heating and gradually form crystals with low Er3+ concentration. Amount of PbErF5 crystals depended upon the initial concentration of Er3+ ions in the parent glasses. EELS analysis also showed that Nd3+ ions were formed inside PbS quantum dots, supporting the proposition of the formation fo Nd-O clusters.