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

Abstract

Abstract: 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 5D0 → 7F0-4 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. Graphical abstract: [Figure not available: see fulltext.]