A novel synthetic route towards monodisperse LaOF:Ln3+ (Ln = Eu, Tb) hollow spheres with multicolor luminescence properties

In this study, monodisperse and uniform LaOF hollow spheres were successfully synthesized through a novel facile synthetic route employing a La(OH)CO3 sphere as a sacrificial template followed by a subsequent calcination process. The structure, morphology, formation process, and luminescence properties were well investigated using various techniques. The possible formation mechanism of evolution from the La(OH)CO3 spheres to the LaCO3F precursor, and to the final LaOF hollow spheres can be attributed to the Kirkendall effect and the decomposition of the LaCO3F precursor. Under ultraviolet excitation, the LaOF:Ln(3+) (Ln = Eu, Tb) hollow spheres show their characteristic f-f emissions and exhibit red, green emissions, respectively. Moreover, by codoping the Tb3+ and Eu3+ ions into the LaOF host and tuning their relative concentration ratio, multicolor tunable emissions are obtained due to the efficient energy transfer from Tb3+ to Eu3+ at 378 nm excitation. This material may find potential application in color display fields.