Floating zone growth and scintillation properties of undoped and Ce-doped GdTaO₄ crystals

Undoped and Ce-doped GdTaO₄ single crystals with different Ce concentration were grown by the floating zone method. By X-ray diffraction analysis, we confirmed all the grown crystals do not have any impurity phases. In X-ray induced scintillation spectra, the undoped sample shows a broad emission band around 300–700 nm, and the decay time of this emission is around 500 ns In Ce-doped samples, emissions are observed around 400–700 nm, and the decay time constants are around 50 ns which is a typical value of the 5d-4f transitions of Ce³⁺. In order to reveal the detailed scintillating behaviors, we measured the temperature dependence of X-ray induced scintillation spectra and revealed the energy transfer mechanisms between two different excited states of luminescent centers.