A similarity between the thermally stimulated luminescence glow curves, of undoped and Ce3+-doped oxyorthosilicates with the monoclinic C2/c structure, strongly suggested that the luminescence traps were intrinsic in origin. They were suggested to be associated with the configuration of the O ions in the vicinity of, not only the Ce3+ ion, but also of the host lanthanide ion. The optical absorption spectra of pristine material revealed the presence of intrinsic absorption centers that were enhanced by X-irradiation, as in the case of other oxides which contained O-related point defects.

Intrinsic Trapping Sites in Rare-Earth and Yttrium Oxyorthosilicates. D.W.Cooke, B.L.Bennett, R.E.Muenchausen, K.J.McClellan, J.M.Roper, M.T.Whittaker: Journal of Applied Physics, 1999, 86[9], 5308-10