The nanoparticles of NaYF 4 : Er 3+ , Yb 3+ , Nd 3+ present fluorescent emissions by upconversion. These emissions are associated with the doping ions of Er, Yb and Nd in the NaYF 4 nanoparticles. The nanoparticles of NaYF 4 doped with Er 3+ and Yb 3+ ions produce upconversion radiation when excited by 980 nm wavelength laser. By incorporating the Nd 3+ ions, the NaYF 4 : Er 3+ , Yb 3+ , Nd 3+ arrangement is formed, which produces the same excitation with an 880 nm wavelength laser, the product of a cross-transfer process between the Nd, the Yb and the Er. For applications in human tissue it is preferable to use a 880 nm wavelength laser. These nanoparticles of NaYF 4 : Er 3+ , Yb 3+ , Nd 3+ have been synthesized in our laboratories with Y (79,3%), Yb (18%), Er (2%) and Nd (0,7%). In this work we have studied the fluorescence behavior of these nanoparticles, which correspond to the transitions 2 H 11/2 → 4 I 15/2 y 4 S 3/2 → 4 I 15/2 , and that can be used in the calibration of a remote nanothermometer, because they have a sensitivity to very small changes in temperature. © Published under licence by IOP Publishing Ltd.