Similarities in glow peak positions and kinetics parameters of oxyorthosilicates: evidence for unique intrinsic trapping sites

Thermally stimulated luminescence measurements on cerium-doped M2SiO5 (M = Lu, Y, Yb, Er) and undoped Lu2SiO5, each possessing monoclinic C2/c crystal symmetry, reveal common glow peaks with the principal one occurring near 375 K. In contrast, cerium-doped Gd2SiO5, characterized by the monoclinic P2(1)/c structure, exhibits a different glow curve with the principal peak occurring near 425 K. Although undoped Lu2SiO5 Shares the characteristic Ce-doped M2SiO5 glow curve, emission spectra data show that it emits weak line-emission, whereas the cerium-doped materials are characterized by the intense Ce3+ band spectrum. This suggests a common and unique trapping site whose formation does not require the presence of cerium. Application of peak-shape glow curve analysis shows that the characteristic peak near 375 K in each sample obeys first-order kinetics with thermal activation energy approx. 1 eV and frequency factor similar to 10(14)s(-1) Based on these results, we suggest that the characteristic glow peak is intrinsic and independent of cerium doping. This unique defect is common to the C2/c-structured oxyorthosilicates and is related to the host metal-ion-ligand configuration. (C) 2001 Elsevier Science B.V. All rights reserved.