Intrinsic conversion efficiency of X-rays to light in Gd2O2S : Tb3+ powder phosphors

Abstract The intrinsic conversion efficiency (ICE) of X-rays to light of Gd2O2S: Tb3+ powder phosphor has been determined according to known methods. The values vary between 0.09 and 0.17 depending on the processing conditions and Tb content. An inverse correlation between ICE values and the decay times of the UV excited green luminescence has been observed. A model of the metastable and nonradiative centres competing with Tb3+ ions, decreasing the energy efficiency transfer and the luminescence yield, is provided.