Luminescence of polymorphous SiO2

A.N. Trukhin, K. Smits, J. Jansons, A. Kuzmin

The luminescence of self-trapped exciton (STE) was found and systematically studied in tetrahedron
structured silica crystals (a-quartz, coesite, cristobalite) and glass. In octahedron structured stishovite
only host material defect luminescence was observed. It strongly resembles luminescence of oxygen
deficient silica glass and g or neutron irradiated a-quartz. The energetic yield of STE luminescence for aquartz
and coesite is about 20% of absorbed energy and about 5(7)% for cristobalite. Two types of STE
were found in a-quartz. Two overlapping bands of STEs are located at 2.5e2.7 eV. The model of STE is
proposed as SieO bond rupture, relaxation of created non-bridging oxygen (NBO) with foundation of a
bond with bridging oxygen (BO) on opposite side of c or x,y channel. The strength of this bond is
responsible for thermal stability of STE. Similar model of STE was ascribed for coesite and cristobalite
with difference related to different structure. STE of Silica glass is strongly affected by disordered

Radiation Measurements 90 (2016) 6e13


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