E. F. Polisadova

Scintillation lithium-phosphate-borate glasses doped by REI

The spectra and decay of luminescence in scintillation glass of the Li2O-B2O3-P2O5-CaF2 system doped by Gd, Gd/Ce, Gd/Pr, Tb, Tb/Ce, and Tb/Eu have been investigated. The technology of synthesis has been described and the evolution of luminescence spectra relative to the electron excitation pulse has been studied. The presence of the buildup stage in the kinetics of terbium ions luminescence was revealed in the bands at 380 and 490 nm. The existence of interaction between ions (Gd and Ce, Tb and Ce, Tb and Eu) has been established. The estimation of the scintillation efficiency of glass with rare earth ions (REIs) has been performed.

Nanodefect substructures in crystal phosphors

We investigated spectral and kinetic characteristics of the luminescence in alkali halide crystals with polyvalent impurities, crystal phosphors based on metal tungstates in the form of nano-, micro- and bulk crystals. The possibility of the existence of complex defects (nanodefects) in materials containing high defect concentration is shown.

The effect of Ce3+ ions on the spectral and decay characteristics of luminescence phosphate-borate glasses doped with rare-earth ions

The luminescent characteristics of Li2O-B2O3-P2O5-CaF2 (LBPC) glasses doped with Gd3+ and Tb3+ ions and codoped with Ce3+ are studied by pulsed optical spectrometry under electron beam excitation. It is found that in glass with Ce3+ and Gd3+ ions a decrease in the decay time of gadolinium luminescence in the 312-nm band (6PJ → 8S7/2) was observed. It is shown that in the glass LBPC: Tb, Ce, an increase in the emission intensity in the main radiative transitions in terbium ion was observed. In the kinetics of luminescence band 545 nm of LBPC: Tb, Ce glasses, is present stage of buildup, the character of which changes with the doped of Ce3+ ions. The mechanism of energy transfer in LBP glasses doped with rare elements is discussed.

Effect of the Li2O: ZnO ratio on the kinetics of cathode luminescence and optical properties of phosphate glass activated by Dy3+

Synthesis of glass system with the composition (mol. %) 50P2O5-(50 - x)Li2O - xZnO + 5 wt % Dy2O3 has been described. IR absorption spectra and the kinetics of cathodeluminescence at x ranges from 0 up to 50 has been investigated. With the replacement of Li by Zn, a decrease of the oxygen ions’ packing density and the average phosphate chain length could be observed. The increase of the ZnO quantity in the glass composition results in the luminescence decay time decreased from 240 to 50 μs in the 481 and 573 nm bands: here, the branching coefficient for the 4F9/2 energy level undergoes changes. The luminescence kinetics are well described by the Inokyti-Hiroyama model for the dipole-dipole mechanism.

Pulsed Cathodoluminescence of ZnWO4:Eu Single Crystals and Nanocrystals

Pulsed cathodoluminescence of zinc tungstate samples doped with europium in the form of single crystals and nanocrystals in the transparent organosilicic matrix is studied. The effect of the size of the crystal on spectral and kinetic parameters of the oxygen luminescence centers is interpreted within the model of self-organization of activator nanodefects during crystal growing.

Luminescence decay kinetics of Eu3+ ions in phosphate glasses of different composition under photo- and electron excitations

The influence of matrix composition, coactivators, and excitation method on the luminescence kinetics of Eu3+ ions in lithium–phosphate and lithium–phosphate–borate glasses activated by Eu, Eu/Tb, and Eu/Dy is studied. Luminescence is excited by a high current electron beam and a xenon lamp. It is found that, under photoexcitation, the europium luminescence decays more slowly than under electronic excitation. Depending on the content of cation modifiers ZnO and Li2O, the decay time decreases with increasing amount of ZnO. The decay time weakly depends on the europium concentration. The decay of the luminescence of europium ions is well described by the Inokuti–Hirayama model.

The effect of codopants on spectral-kinetic characteristics of luminescence of scintillation glasses doped with terbium ions

The effect of Ce3+ and Pr3+ ions on spectral-kinetic characteristics of luminescence of lithium–phosphate–borate glasses is studied. It is shown that terbium ion luminescence caused by transitions from 5D3 and 5D4 multiplets to the ground 7FJ term is detected in samples containing Tb3+/Ce3+ and Tb3+/Pr3+. It has been found that an increase in the concentration of cerium ions from 0.2 to 1 wt % leads to an increase in the intensity of main luminescence bands of terbium ions. In Tb3+/Pr3+ glasses, a decrease in the relative light yield is observed with an increase in the concentration of Pr3+ ions. Processes of energy transfer between Tb3+/Ce3+ and Tb3+/Pr3+ ions are discussed.

Cathodoluminescence Properties of Commercial Phosphors for White LED

The results of the study of spectral and decay kinetic characteristics of the pulse cathodoluminescence (PCL) for the group of industrial “white” LEDs phosphors with different composition of the host and dopants are presented. The quantitative characteristics of the PCL: position and half-width of the luminescence spectra, the luminescence decay times were determined.