Synthesis and luminescent properties of ellipsoid-like YBO3:Ln3+ (Ln = Eu, Tb)

A series of YBO3:Ln3+ (Ln = Eu, Tb) phosphors have been successfully synthesized for the first time via a simple solution-based hydrothermal method using Y(OH)CO3:Ln3+ (Ln = Eu, Tb) colloid spheres and Na2B4O7·10H2O as the precursors. The as-prepared phosphors present uniform ellipsoid-like morphology and have a diameter of about 2.5 μm. FTIR confirms the formation of vaterite-type YBO3 can be synthesized by this method. The molar ratio of Y/B plays an important role in controlling the product morphology. The possible formation mechanism for the ellipsoid-like microcrystals was proposed on the basis of a series of time-dependent experiments. Even in such a simple solution-based hydrothermal reaction system, the formation of YBO3 microcrystals went through complex crystallization and crystal growth processes: a small amount of random shaped particles served as precursors for the crystals initially formed which continuously grew into large flower-like YBO3, the excess borax resulted in the dissolution of flower-like YBO3 and the formation of new YBO3 particles. Moreover, there exists characteristic luminescence of Eu3+ and Tb3+ individually when doping them in the YBO3 host. The quenching concentration of YBO3:Eu3+ and YBO3:Tb3+ is 25% and 20%, respectively.