科研之友
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摘要
A series of novel red-emitting phosphor of Li5La3-3xEu3xTi2O12 (x= 0.01-0.25) were synthesized via the facile solid-state reaction method. The Rietveld refinements verified that all the samples crystallized in a garnet-like cubic structure. The band gap energy of Li5La3Ta2O12 is 3.87 eV, which can be greatly narrowed by Eu3+-doping. This benefits the red-shift of optical absorption from UV- to near-UV light region. Importantly, the sample presents dominant absorption in near-UV (390-395 nm) and blue-light (460-465 nm) region. Li5La3-3xEu3xTa2O12 (x= 0.01-0.15) has a bright red-luminescence with the strongest D-5(0) -> F-7(2) transition at 613 nm. The energy transfer was discussed on the Eu3+-doping concentration. The experimental red-emitting lamps were fabricated using a 395 and a 460 nm LED-chips, respectively, in combination with the single phosphor of Li5La3-3xEu3xTa2O12 (x= 0.2) driven by 2 mA current. The results indicate that the phosphor could be a promising candidate used in solid-state lightings and displays.
