Thermoluminescent properties of tridymite SiO2 : Al3+, Eu3+

SiO2 crystals have been used in electroluminescence devices and thermolumin escence (TL) dosimeters. However, their emission mechanisms have not yet be en clearly explained. Recently, it has become possible to obtain amorphous, highly pure, SiO2 prepared by the sol-gel method. The emission mechanism o f TL was investigated using Al3+ and/or Eu3+-doped SiO2 crystalline samples prepared by heat-treating under much lower temperature than the melting po int of SiO2. The TL spectrum of Eu3+-doped sample had main peaks due to the electron transitions from D-5(2) to F-7(5) (ca. 570 nm, yellow peak) and f rom D-5(0) to F-7(2) (ca. 610 nm, red peak). The yellow peak intensity has a maximum value in the SiO2 doped with near 1 mmol% of Eu2O3, while the red peak intensity was almost constant. These facts suggest that bright yellow emission of SiO2TL phosphor is synthesized by the diffusion of Eu3+ ion in SiO2 matrix prepared by sol-gel method.