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

5 mol% Eu3+ doped NaYF4 (alpha-, beta-), YE3, YF3 center dot 1.5NH(3), NaGdF4, and LaF3 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, Eu3+ shows different optical properties in the above samples. It has stronger luminescent intensity in beta-NaYF4 than that in alpha-NaYF4 while it exhibits different higher energy D-5(1.2) to lower F-7(J) emissions as well as the asymmetric ratios and the splits of D-5(0) -> F-7(1), F-7(4). YF3, LaF3, and beta-NaGdF4 have analogous optical intensities to those of beta-NaYF4. However, beta-NaGdF4 has the similar spectral profile to that of beta-NaYF4 while YE3 and LaF3 have the opposite cases in the D-5(0) -> F-7(2), F-7(1) emissions. Further, Judd-Ofelt calculation has been used to analyze the experimental phenomena. (C) 2011 Elsevier Ltd. All rights reserved.