Red-emitting BaAl2O4:Eu3+ synthesized via Pechini and sol-gel routes: a comparison of luminescence and structure

摘要

UV-to-red downshifting phosphors such as BaAl2O4:Eu3+ find broad range of application in sensors, displays, and in solid-state lighting, yet new synthetic routes to improve their luminescence are envisaged. In this regard, herein, it is introduced two new methods to synthesize this environmentally friendly BaAl2O4:Eu3+, by an adapted sol-gel route and a modified Pechini synthesis. Additionally, a systematic study was carried out about the Eu3+ doping concentration and charge compensation effects on the structural, morphological and spectroscopic features. Both routes enabled high-crystalline and nanostructured phosphors displaying optic bandgap near to 4.4 eV, although the sol-gel route also led to low amounts of BaCO3 spurious phase. Upon UV (250 nm) excitation, all Eu3+-doped samples emit red light displaying high emission color purity, characteristic of the D-5(0) -> F-7(0-4) electronic transitions of Eu3+. The Pechini method led to the highest intrinsic emission quantum yield (85% for the 3%-doped sample). Eu3+ replaces Ba2+ within the BaAl2O4 lattice, but in the sol-gel-derived samples, the dopant may also replace Ba2+ into the BaCO3 spurious phase, confirming that the Pechini route is the best one to optimize the luminescence and structure of the phosphor. [GRAPHICS] .