Influence of Li dopants on thermoluminescence spectra of CaSO4 doped with Dy or Tm
No Thumbnail Available
Date
2011
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Abstract
Thermoluminescence emission spectra are presented for lithium doped variants of CaSO4:Dy or CaSO4:Tm dosimetry material. All three dopants (Li, Dy and Tm) variously introduce different changes in both the glow peak temperatures and the luminescence efficiency. In every case the emission signals display the line emission characteristic of the rare earth ions. At temperatures below ∼50 K the relative peak intensities differ for Dy and Tm doped samples, and there are small temperature shifts between the Dy:Li and Tm:Li co-doped materials. Above room temperature the rare earth ions do not show peak temperature movements when co-doped with lithium. However they do influence the peak temperature by ∼5 °C when they are the sole dopant. Inclusion of lithium dramatically moves the high temperature glow peak from ∼200 °C down to 120 °C. All these changes are consistent with a single defect model in which the trapping sites and luminescence occur within the complexes formed of the rare earth ion, an intrinsic sulphate defect and lithium. The evidence and rationale for such a model are presented. There is discussion which suggests that such defect complexes are the norm in thermoluminescence. © 2011ElsevierB.V.Allrightsreserved.
Description
Keywords
Defects , Doping (additives) , Emission spectroscopy , Metal ions , Rare earths , Thermoluminescence , :Dy, Li , :Tm, Li , Co-doped , Defect complex , Emission signal , Emission spectrums , Glow peaks , Glow-peak temperature , High temperature , Li-dopants , Line emissions , Luminescence efficiencies , Peak temperatures , Rare earth ions , Relative peak intensity , Room temperature , Single defect , Sulphates , Temperature shift , Thermoluminescence spectrum , Tm-doped , Trapping sites , Lithium