Photoluminescence, radioluminescence, and thermoluminescence in NaMgF3 activated with Ni2+ and Er3+

Photoluminescence (PL) and radioluminescence (RL) has been observed at infrared wavelengths in NaMgF3 doped with Er3+ or Ni2+. The RL contains more emissions than seen in the PL, which is likely to be due to radiation induced excitations to higher energy excited states of the luminescent ion than are accessible during PL. Both luminescent ions have relatively long PL lifetimes and the long wavelength RL emission intensities are independent of absorbed dose history for high doses. This, coupled with the approximate radiological equivalence of NaMgF3 to water are desirable properties for a dosimeter for radiotherapy applications. The Čerenkov component seen for high energy radiation sources can be reduced by monitoring the longer wavelength RL emissions, or by temporal discrimination for pulsed sources. Room temperature glow peaks are seen in the NaMgF3:Er3+ thermally stimulated luminescence emission that imply the RL will be temperature dependent. This is not the case for NaMgF3:Ni2+ where no thermoluminescence is observed, hence Ni2+ is preferred over Er3+ for radiotherapy applications.