Valency change of Cr, Fe, Cu, Er, Ce dopants inside oxide compounds under proton irradiation

Valency changes of Ce, Er, Cu and Cr active ions and non-controlled Fe ions in Y3Al5O12:Ce and Y3Al5O12:Ce,Mg, SrGdGa3O7:Cr, YAlO3:Er and LiNbO3:Cr si ngle crystals under proton irradiation were observed. For all investigated crystals the dose dependence of additional absorption was determined. For s mall proton fluencies (10(13)-10(14) particles/cm(2)), the recharging effec ts are mainly observed. For fluencies greater than 10(14) cm(-2), the ioniz ation effects and Frenkel defects are observed, for fluencies >10(15) cm(-2 ) the Frenkel defects dominate. Changes in luminescence of Ce doped Yl(2)Al (3)O(12) crystals depend on initial Ce concentration and are greater for Ce concentration <0.05 at.% and smaller for Ce concentration >0.1at.%. Gamma spectra from nuclear reaction products were also measured. The accuracy of the intensity measurement of the 0.208 MeV gamma line from Tm-167 in YAlO3: Er crystal is 0.14%, including the statistical and systematic errors. From extrapolation of the above result to lower Er contents, one can expect that 0.1 at.% is a detectable Er concentration level in the crystal. (C) 1999 E lsevier Science S.A. All rights reserved.