Synthesis and spectral properties of colloidal Nd3+ doped NaYF4 nanocrystals

Transparent, chloroform dispersed α-NaYF4 nanocrystals doped with neodymium ions were synthesized and characterized. XRD and TEM measurement confirmed cubic structure of α-NaYF4 of the nanoparticles (NPs). The absorption and emission spectra as well as 4F3/2 level fluorescence decay curves were measured in order to estimate the influence of Nd3+ concentration in the matrix on the optical properties of the NPs. With the increase of Nd3+ doping level, the Judd–Ofelt Ω4 parameter as well as the spectroscopic Nd3+ parameter XNd = Ω4/Ω6 was growing. In the same time the Ω2 and Ω6 were decreasing. Theoretical luminescence lifetimes of the 4F3/2 level equal to ∼300 μs were also calculated and compared with the experimental values to quantify the concentration quenching. Based on this comparison, quantum efficiency was found to vary systematically between ∼100% and 4% for Nd3+ content increasing from 2 up to 25%.

■■■.Figure optionsDownload high-quality image (300 K)Download as PowerPoint slideResearch highlights
► Up to 25% Nd3+ did not change the structure/morphology of the NaYF4 nanocrystals.
► Nd3+ doping predictably controls the cross-relaxation and QY of luminescence.
► The increase of Nd3+ doping leads to Ω4 and Ω4/Ω6 growth and to Ω2 and Ω6 decrease.