Hydrothermal synthesis, energy transfer and luminescent properties of β-NaLuF₄:Ce³⁺/Gd³⁺/Sm³⁺ microcrystals

In this study, Ce³⁺, Gd³⁺ and Sm³⁺ co-doped β-NaLuF₄ micro-prisms with prominently uniform shape and size have been successfully prepared by a facile and efficient hydrothermal strategy. By modifying the dopant concentration of migrator (Ce³⁺) and activator (Sm³⁺), the luminescent properties of β-NaLuF₄:Ce³⁺/Gd³⁺/Sm³⁺ samples are systematically studied and the corresponding energy transfer (ET) mechanism can be discussed in detail. Impressively, upon the excitation into the electric-dipole-allowed 4f→ 5d transition of Ce³⁺ ions at 250 nm, the efficient ET from Ce³⁺ ions (sensitizer) to Sm³⁺ ions (activator) can be realized through the Ce³⁺→(Gd³⁺)_n→Sm³⁺ energy migration process, in which the Gd³⁺ (migrator) acts as a bridge center to yield intense orange emission from Sm³⁺ ions. The above results not only enrich the knowledge of the synthetic chemistry and optical spectroscopy of luminescent materials, but also endow such materials with potential applications in a diversity of fields.