Controlled synthesis and photoluminescence of europium doped barium borate nanorods, nanowires, and flower-like assemblies

Novel luminescent nanomaterials, europium (Eu³⁺) doped barium borate (Ba-B-O:Eu³⁺) nanorods, nanowires, and flower-like assemblies, were synthesized for the first time by a hydrothermal (HT) method. Morphologies of these Ba-B-O:Eu³⁺ nanocrystals (NCs) can be controlled by adjusting oleic acid (OA) concentration, pH value, and reaction time. SEM and TEM observations indicate that the morphologies are determined by the anisotropic growth of the NCs and Ostwald ripening in their formations. Spectral analysis shows that the Ba-B-O:Eu³⁺ NCs, especially the flower-like assemblies, have not only strong emission intensities but also high I(⁵D₀→⁷F₂)/I(⁵D₀→⁷F₁) ratios, which is promising for applications in displays and optical devices.