Forgotten and Resurrected Chernovite-(Y): YAsO Doped with Eu Ions as a Potential Nanosized Luminophore.

In the present work, a precipitation method was employed to prepare nanosized YAsO doped with Eu ions. The raw nanomaterials have been thermally treated in a temperature range between 500 and 900 °C for 3 h. The XRD analysis demonstrated that the powders were single-phase nanopowders with high crystallite dispersion. Our studies were focused on relating the luminescence properties of the Eu dopant to the nanocrystallite (NC) size. The average NC size varied accordingly between 15 and 45 nm. We have found that the size effect is manifested mainly in the expansion of the cell volume and broadening of XRD peaks, as indicated by Rietveld analysis. Moreover, the emission and excitation spectra, although typical for Eu ions, demonstrated some degree of variability with calcination temperatures and doping concentration. To explain these differences, a detailed analysis of luminescence spectra by the Judd-Ofelt theory has been performed.