Local Structure of the Infrared Bismuth Luminescent Center in Bismuth-Doped Silica Glass

Several instrumental analyses, such as spectroscopic properties, luminescent intensity, nuclear magnetic resonance, X-ray diffraction, electron spin resonance, X-ray photoelectron spectroscopy, and extended X-ray absorption fine structure, have been performed on a Bi2O3-Al2O3-SiO2 glass system. After the roles and the structure of the Al ions and the valence state of the luminescent Bi ions were experimentally examined, it was recognized that aluminum ions with a sixfold corundum structure behave like a "generator" of the luminescent center and that the valence state of Bi5+ is suitable for the distinctive Bi luminescent center. Because a certain image of the local structure of the Bi luminescent center is built by instrumental analyses without discrepancies, the distinctive bismuth luminescent center model reveals that the sixfold coordination state of Bi5+ is combined with the sixfold corundum structure of Al3+ through an oxygen ion.