Synthesis and spectral properties of colloidal Nd3+ doped NaYF4 nanocrystals

Transparent, chloroform dispersed alpha-NaYF4 nanocrystals doped with neodymium ions were synthesized and characterized. XRD and TEM measurement confirmed cubic structure of alpha-NaYF4 of the nanoparticles (NPs). The absorption and emission spectra as well as F-4(3/2) 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 Omega(4) parameter as well as the spectroscopic Nd3+ parameter X-Nd = Omega(4)/Omega(6) was growing. In the same time the Omega(2) and Omega(6) were decreasing. Theoretical luminescence lifetimes of the F-4(3/2) level equal to similar to 300 mu s 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 similar to 100% and 4% for Nd3+ content increasing from 2 up to 25%. (C) 2011 Published by Elsevier B.V.