Defect disorder and optical spectroscopy study of Eu-doped NaYF4 and NaYGdF4 nanoparticles

Optical spectroscopy and defect disorder of Eu-doped NaYF4 and NaY1-xGdxF4 structures were studied by computational and experimental methods. Atomistic modeling was used to make predictions about the intrinsic disorder, Eu doping sites, charge compensation schemes, and to predict the microssymmetry and detailed geometry of the dopant site. This information was used to calculate the crystal field parameters and obtain the 7F1 sublevels of the Eu3+ ion, which we used to discuss the local symmetry of the Eu3+ in the NaYF4 and NaYGdF4 structures. The experimental emission spectrum was obtained for NaYF4:Eu and NaYGdF4:Eu structures prepared by the thermal decomposition methodology. The theoretical spectroscopic study showed that the symmetry of the Eu3+ ions, based on the amount of non-null crystal field parameters is a slightly distorted S6 symmetry and D3d symmetry in the α-NaYF4 and α-NaYGdF4 structures, respectively, and a distorted C3h symmetry in the β-NaYF4 and β-NaYGdF4 structures. A set of phenomenological charge factors and the 7F1 manifold split were satisfactorily reproduced in agreement with the experimental data. •The defect disorder of Eu-doped NaYF4 and NaY1-xGdxF4 structures are studied.•Atomistic modeling is used to make predictions of intrinsic disorder, Eu doping sites, charge compensation schemes.•The experimental emission spectrum was obtained for NaYF4:Eu and NaYGdF4:Eu structures.•Crystal field parameters was calculated and used to obtain the 7F1 sublevels of the Eu3+ ions.