Segregation of Pr³⁺ ions in YPO₄:Pr³⁺nanocrystals was revealed by means of spectroscopic techniques. Increase of doped ions concentration in the near-surface layer of YPO₄:Pr³⁺ nanocrystals was confirmed by modification of luminescence spectra and decay curves depending on the heat treatment temperature. Relaxation of excess elastic stresses created by Pr³⁺ ion with volume greater than volume of regular Y³⁺ ion was determined to be the main cause of observed effects. Theoretical estimations obtained are in a good agreement with the experimental data
