Study of effects of rare earth impurities on structure of matrix emission of the lead tungstate crystals

The paper reports study of complex structure of matrix emission of undoped and RE-doped PbWO4 crystals. Decomposition of the spectra shows contributions of five components at 410, 485, 520, 565, 635 nm in emission of all the investigated samples. Their relative contributions depend on RE doping. Observed effects of RE doping are the same for the crystals with different RE impurities. Structures of luminescent centres are discussed taking into account studied effects of the impurity RE ions on spectral characteristics of the matrix emission

Structure of Centers of Matrix Emission of the Undoped and RE-Doped Scheelite-Type Lead Tungstate Crystals

The paper reports the investigation of a structure of luminescence spectra of PbWO4 (PWO) crystals. The doping of the samples with rare earth (RE) impurities is used in order to obtain more information about the composition of spectra of the PWO matrix emission and the structure of its luminescence centers. The decomposition of the emission spectra onto individual bands has shown that 5 bands contribute to the total spectra of all the undoped and RE-doped samples at 10 K. The maxima of the obtained bands are 1.95, 2.2, 2.45, 2.7, and 3.0 eV. Effects of the RE-doping and the annealing on relative intensities of these bands are considered. The nature of luminescence and the structure of the centers involved in the excitation and emission processes responsible for each of the separated bands are discussed

Study of RE-impurity effects on exciton luminescence of PWO4PWO_{4} single crystals grown by Czochralski method

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

Luminescent Spectroscopy of the Yb³⁺ Ions in the PbWO₄ Crystal

Luminescent properties of the PbWO₄ crystals undoped and doped with the Yb³⁺ ions were studied. Emission spectra of the crystals consist of broadband matrix emission in 350-750 nm spectral range and narrow spectral lines caused by inner electron transitions in the impurity Yb³⁺ ions in 920-1040 nm spectral range. Analysis of the linear spectra has shown that Yb³⁺ ions form two types of emission centres. Structures of these centers are discussed taking into account possibility of the impurity ions incorporation in different positions (Pb and W sites) in the crystal lattice. Effects of the Yb³⁺ impurities on matrix emission were studied. Transfer of excitation energy from matrix to the Yb³⁺ decreases intensity of the red band of matrix emission. The Yb³⁺ impurities also increase intensity of the blue band by formation of additional Yb³⁺-induced channel of excitation of this band. The described effects of Yb³⁺ doping on properties of matrix emission are caused by the Yb³⁺ ions arranged in Pb positions

Luminescent Spectroscopy of the Yb3+^{3+} Ions in the PbWO4_4 Crystal

Luminescent properties of the PbWO$_4$ crystals undoped and doped with the Yb$^{3+}$ ions were studied. Emission spectra of the crystals consist of broadband matrix emission in 350–750 nm spectral range and narrow spectral lines caused by inner electron transitions in the impurity Yb$^{3+}$ ions in 920–1040 nm spectral range. Analysisof the linear spectra has shown that Yb$^{3+}$ ions form two types of emission centres. Structures of these centers are discussed taking into account possibility of the impurity ions incorporation in different positions (Pb and W sites) in the crystal lattice. Effects of the Yb$^{3+}$ impurities on matrix emission were studied. Transfer of excitation energy from matrix to the Yb$^{3+}$ decreases intensity of the red band of matrix emission. The Yb$^{3+}$ impurities also increase intensity of the blue band by formation of additional Yb$^{3+}$-induced channel of excitation of this band. The described effects of Yb$^{3+}$ doping on properties of matrix emission are caused by the Yb$^{3+}$ ions arranged inPb positions