Glycothermal synthesis and photoluminescent properties of Ce ³⁺-doped YBO₃ mesocrystals

We report a glycothermal synthesis of Ce³⁺-doped YBO₃ mesocrystals and their Ce³⁺-concentration dependence of particulate and photoluminescent properties. Submicrometer-sized YBO₃:Ce ³⁺ disk-like particles with Ce³⁺ concentrations of 0-3 at.% were formed from trimethyl borate and acetates of yttrium and cerium(III) via a glycothermal reaction at 300 °C for 2 h in 1, 4-butanediol. The size of the particles decreased from ∼1.5 μm to ∼150 nm with increasing the Ce³⁺ concentration up to 1 at.%. Selected area electron diffraction revealed that each disk-like particle was a mesocrystal, i.e., an assembly of nanocrystals with a uniform crystallographic orientation, irrespective of the Ce³⁺ concentration. The particles showed blue emission through 5d-4f transitions of Ce³⁺ under near-UV excitation. Concentration quenching of the Ce³⁺ emission for the glycothermally-prepared YBO₃:Ce³⁺ started from a lower Ce³⁺ concentration than that of solid-state-prepared bulk YBO ₃:Ce³⁺, indicating an inhomogeneous distribution of Ce³⁺ ions in the mesocrystals.