27Al NMR structural study on aluminum coordination state in bismuth doped silica glass

The aluminum coordination state in bismuth doped silica glass, which has new broad infrared emission at 1.3 μm regions, was investigated by using ²⁷Al NMR, and it is demonstrated that 6-fold coordinated aluminum ions with corundum structure are dominant in bismuth doped silica glass until Bi₂O₃ concentrations of 1.0 mol% with Al₂O₃. The aluminum ion efficiently affects the creation of a Bi luminescent center at an intensity of Bi₂O₃ (1.0 mol%)–Al₂O₃ (2.3 mol%)–SiO₂ (96.7 mol%); the sample is three orders of magnitude larger than the Bi₂O₃ (1.0 mol%)–SiO₂ (99.0 mol%) sample. Aluminum ions with corundum structure in silica glass have a very important role for the configuration of peculiar Bi luminescent centers.