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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Cathodoluminescence of oxyfluoride glass-ceramics

U. Rogulis, E. Elsts , J. Jansons , A. Sarakovskis , G. Doke , A. Stunda , K. Smits

Tb, Ce, Eu activated oxyfluoride glass-ceramics with the composition SiO2 $ Al2O3 $ Li2O $ LaF3 have been
studied by cathodoluminescence (CL). We compared CL intensities and decay times of the Tb, Ce, Eu
activated glass-ceramic samples and observed that the Tb activated sample has the most intense
luminescence, but the Ce activated sample has the shortest decay times. Induced optical absorption and
thermostimulated luminescence have been observed after X-ray irradiation of samples.

Radiation Measurements xxx (2013) 1-4

DOI: 10.1016/j.radmeas.2012.12.020

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The luminescence of ZnO ceramics

L. Grigorjeva , D.Millers , K.Smits , J.Grabis , J.Fidelus , W. qojkowski , T.Chudoba , K.Bienkowski 

The luminescence properties of ZnO ceramics with grains 100-5000 nm sintered by different techniques from nanopowders were studied. The luminescence decay times were compared with that obtained for ZnO singlecrystal. The temperature dependence of non-exponential decay of defect luminescence (2.0-2.6 eV) was measured in wide time, intensity and temperature range.The luminescence decay kinetic at T=20 K shows the decay close to I(t) w t1 dependence. At temperature region 50-250 K the decay kinetics is more complicated since the TSL was observed in this temperature region. It is shown that the luminescence properties of NP and ceramics strongly depend on defect distribution on grains surface
and the volume/surface ratio determine the luminescence decay in ZnO nanostructures and ceramics.

Radiation Measurements


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