Synthesis and properties of Tb3Al5O12:Eu3+ garnet phosphor

Eu3+-activated Tb3Al5O12 (TAG:Eu3+) reddish orange-light emitting garnet phosphor was synthesized by the metal-organic decomposition method and subsequent calcination at Tc = 1200 °C in air. The luminescence properties of the TAG:Eu3+ phosphor were investigated in detail using photoluminescence (PL) spectroscopy, PL excitation (PLE) spectroscopy, and luminescence decay time measurements. The PLE spectra and luminescence decay behaviors of the Eu3+/Tb3+ emission showed an evidence of resonant energy transfer from the TAG host (Tb3+) to Eu3+. Temperature dependence of the Eu3+ emission intensity measured at T = 20-300 K was successfully analyzed by the conventional quenching model with considering a term of the phonon occupation number, which reflected gaining of the parity-forbidden Eu3+ (4f6 → 4f6) emission intensity. The PL decay process of the Tb3+ emission in TAG was also observed to be very fast with an average decay time of τav ∼ 0.3 ms. The reason for this is that a very strong or a self-concentration quenching occurs in stoichiometric terbium compound of TAG (i.e., 100% of terbium compound). As expected, the very fast Tb3+ emission decay time was also observed from a companion pair of Tb3Ga5O12 (TGG) with τav ∼ 0.5 ms.