The luminescence characteristics of Te- and Bi-doped glasses and glass-ceramics were investigated and the origin of coloration and near infrared luminescence was discussed. The colorations of these glasses and glass-ceramics might be due to the elemental clustering, such as Te2/Te2 - and Bi2/Bi2 -. The broad near infrared (NIR) luminescence can be detected in Te- and Bi-doped glasses and glass-ceramics. The electron spin resonance (ESR) signal at g≈2.0 was observed in Te- and Bi-doped glasses and glass-ceramics, which exhibit NIR luminescence, and therefore this ESR signal is strongly related to the NIR luminescence. The ESR signal at g≈2.0 might be derived from molecular ions of Te and Bi, Te2 - and Bi2 -. Consequently, it is suggested that the broad NIR luminescence of Te- and Bi-doped glass and glass-ceramics are most likely to be caused by elemental clustering, such as Te2/Te2 - and Bi2/Bi2 -.
2007 The Ceramic Society of Japan