Enhancement of Fluorescent Intensity of a SiO2 : Sm Glass by Al Codoping and Local Structure around Sm by an EXAFS Study

Abstract

Al codoped phosphors were prepared by the alkoxide method, which starts from a hydrolysis of silicon ethoxide and the metal nitrates at low temperature and minimizes the contamination of impurities. An addition of Al ions to is found to increase emission intensity from Sm ion more than an order of magnitude. EXAFS study revealed that local structures around Sm ions in the phosphors with and without dopant are significantly different; in the phosphor Sm atoms are well dispersed at low Sm concentrations and Sm atoms agglomerate at high concentrations, while in the Al codoped phosphor Sm atoms are coordinated by Al through Sm‒O‒Al bonding. This provides a direct structural evidence of the role of the codopant.