Changes in Luminescence of Ce:yag Crystals Under Ionizing Radiation Treatment

S.M. Kaczmareka, Z. Morozb, M. Kwasnya, J. Kisielewskic, T. Lukasiewiczc,d, J. Wojtkowskab and H. Rzewuskie aInstitute of Optoelectronics, M.U.T., Kaliski 2, 01-489 Warsaw, Poland bSoltan Institute of Nuclear Studies, 05-400 Swierk, Poland cInstitute of Electronic Materials Technology, Wolczynska 133, 01-919 Warsaw, Poland dInstitute of Applied Physics, M.U.T., Kaliski 2, 01-489 Warsaw, Poland eInstitute of Nuclear Chemistry and Technology Dorodna 16, 03-195 Warsaw, Poland

Received: July 27, 1998; revised version February 19, 1999

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Radiation induced changes in the luminescence spectrum under influence of UV light, γ-rays, electrons and protons for several concentrations of Ce3+ ions as well as Mg2+ ions in yttrium-aluminum garnet crystals were investigated. To irradiate with γ and electron as grown crystals were used while for proton irradiations the crystals were thermally annealed. For small concentrations of cerium ions (≈0.01 at.%) an increase in the luminescence (about 100%) was observed after gamma irradiation with a dose of 105 Gy. This increase was due to the growth in Ce3+ ions concentration after γ-irradiation (≈50%), due to the Ce4+ → Ce3+ recharging reaction. For highly doped Ce:YAG crystals (0.1 at%, 0.2 at.%) also an increase, but much smaller (4%), for the Mg codoped crystals (0.1 at.%) was observed. After 1 MeV electron irradiation in the over-threshold type interaction a decrease in luminescence is observed due to the domination of the Ce3+ → Ce4+ ionization process. In the case of the proton irradiation, for small fluencies (≈1013 particles/cm2) an increase in luminescence is observed due to the domination of the recharging processes of Ce4+ ions. For larger fluencies (>1014 particles/cm2) a decrease takes place due to a high level of radiation defects.

DOI: 10.12693/APhysPolA.95.953 PACS numbers: 61.72.Ji, 61.80.Ed