Hydrothermal synthesis and optical properties of Eu3+ doped NaREF4 (RE = Y, Gd), LnF3 (Ln = Y, La), and YF3·1.5NH3 micro/nanocrystals

Abstract 5 mol% Eu 3+ doped NaYF 4 (α-, β-), YF 3 , YF 3 ·1.5NH 3 , NaGdF 4 , and LaF 3 micro/nanocrystals have been synthesized by a hydrothermal method. The final products are characterized by X-ray diffraction, field emission scanning electron microscopy, photoluminescence excitation and emission spectra, and luminescent dynamic decay curves. Due to its sensitivity to local symmetry, Eu 3+ shows different optical properties in the above samples. It has stronger luminescent intensity in β-NaYF 4 than that in α-NaYF 4 while it exhibits different higher energy 5 D 1,2 to lower 7 F J emissions as well as the asymmetric ratios and the splits of 5 D 0 → 7 F 1 , 7 F 4 . YF 3 , LaF 3 , and β-NaGdF 4 have analogous optical intensities to those of β-NaYF 4 . However, β-NaGdF 4 has the similar spectral profile to that of β-NaYF 4 while YF 3 and LaF 3 have the opposite cases in the 5 D 0 → 7 F 2 , 7 F 1 emissions. Further, Judd–Ofelt calculation has been used to analyze the experimental phenomena.