Luminescent properties of amorphous phosphor 1.4Y2O3·2.5Al2O3·0.1Tb2O3 prepared by sol-gel method

Amorphous phosphor 1.4Y2O3.2.5Al2O3.0.1Tb2O3 (the same composition as Y2.8Tb0.2Al5O12) was prepared via a sol-gel method at relatively low temperature (i.e., below 650 °C), which is much lower than that for the preparation of polycrystalline Y3Al5O12:Tb3+ (above 1400 °C). The amorphous phosphor prepared in the optimized conditions showed a bright green-yellowish luminescence, the intensity of which was comparable with that of polycrystalline sample and the emissions of which were assigned to 5D4 → 7Fj transitions of Tb3+. Besides the emissions of Tb3+, the amorphous samples prepared at temperatures below 500 °C presented a weak blue emission band around 420 nm.