Study of RE-impurity effects on exciton luminescence of PWO4 single crystals grown by Czochralski method

Abstract Spectral-luminescent properties of matrix emission of pure and RE-doped lead tungstate crystals were investigated using excitation in the 3.7–8.0 eV energy range and emission in the 1.5–3.5 eV energy range. The observed differences between positions of exciton peaks in the excitation spectra of the pure and RE-doped crystals are the same for all the investigated impurity ions (RE = Yb3+, Eu3+, Pr3+). Existence of two types of centres responsible for creation of excitons in the undoped lead tungstate crystals is shown. It is supposed that these centres contain Pb cations of the regular crystal lattice and different types of defects. Conditions of formation and properties of the both types of centres are discussed. Observed effects of the impurity RE ions on excitation and emission spectra of the blue luminescence are explained by using some proposed models.