Luminescence of X-ray induced radiation defects in modified lithium orthosilicate pebbles with additions of titanium dioxide

Abstract

Modified lithium orthosilicate (Li₄SiO₄) pebbles with additions of titanium dioxide (TiO₂) are designed as a possible tritium breeder ceramic for the helium cooled pebble bed (HCPB) test blanket module. Additions of TiO₂ were chosen to enhance mechanical properties of the tritium breeder pebbles. The formation of radiation defects (RD) in the modified Li₄SiO₄ pebbles with a different content of TiO₂ was studied by X-ray induced luminescence (XRL) technique. After XRL measurements the accumulated RD were also analyzed by thermally stimulated luminescence (TSL) and electron spin resonance (ESR) spectrometry. XRL spectra consist of several bands with maxima at around 430, 490, 690, 700 and 800 nm. The XRL band with a peak at 490 nm could be associated with intrinsic defects in Li₄SiO₄ matrix whereas all the other maxima at lower photon energies are the result of the addition of TiO₂