Energy Transfer Phenomena in GdF3:Mn Co-doped with Ce3+, Pr3+ or Zr4+

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We studied the effects of Mn2+ doping and Ce3+ or Pr3+ or Zr4+ co-doping on the scintillation characteristics of GdF3 powder crystals including excitation-emission spectra and decay time for UV excitation, light yield (LY) and luminescence spectra for X-rays. In GdF3:Mn2+, the dominant Mn2+ emission occurred at 515 nm with a decay constant $\tau \sim 24$ ms for excitation at 275 nm. The LY increased monotonically as the Mn2+ concentration decreased from 1 at.% down to 20 at.ppm, indicating very efficient $\text{Gd$^{3+}$} \rightarrow \text{Mn$^{2+}$}$ energy transfer and possible concentration quenching at large Mn2+ concentrations. The maximum LY for X-rays was about 19% of Gd2O2S:Pr3+,Ce3+, one of the brightest ceramics scintillators employed in X-ray computed tomography. While efficient energy transfers of $\text{Ce$^{3+}$} \rightarrow \text{Gd$^{3+}$}$ and $\text{Ce$^{3+}$} \rightarrow (\text{Gd$^{3+}$})_{n} \rightarrow \text{Mn$^{2+}$}$ were observed for a wide range of Mn2+ concentrations (0.01 to 1 at.%), the inverse energy transfer from Gd3+ to Ce3+ was absent or weak.
2003-04-15