NEAR INFRARED LUMINESCENCE FROM BI-DOPED SODA-LIME-SILICATE GLASSES

The effect of melting atmosphere on the luminescent characteristics of Bi-doped soda-lime-silicate glasses was investigated, and the origin of NIR luminescence was also discussed. The appearance of these glasses changed from colorless and transparent to deep brown depending on the melting atmosphere (amount of carbon addition). The characteristic absorption bands can not be observed in all glasses. The colorless and transparent glass (C1.50) exhibit both UV-VIS and MR luminescence. The UV-VIS luminescence comes from Bi3+ ion, which remains in glasses. On the contrary, the NIR luminescence is derived from Bi clustering, such as Bi-2 or Bi-2(-), and therefore transparent colorless C1.5 glass contains both Bi3+ ion and Bi-2 or Bi-2(-). The ESR measurements confirmed that the ESR signals derived from molecular clustering of Bi, Bi-2(-) can be detected at g similar to 2.0. Consequently, it is found that the molecular clustering of Bi, Bi-2 or Bi-2-, might be produced under the mild reducing condition.