Increasing the Intensity of the Glow of the Phosphor Gd-=SUB=-2-=/SUB=-O-=SUB=-2-=/SUB=-S : Tb(3-7 Mol.%), Caused by a Change in the Distribution of the Tb-=SUP=-3+-=/SUP=- Activator over the Real Crystal Lattice

Luminophores Gd2O2S : Tb(3-7 mol.%), obtained through the stage of sol-gel formation of Gd2O3 : Tb precursors with their subsequent sulfidation in sulfur vapor with LiF flux at 700oC, showed high luminescence efficiency. The characterization of the obtained samples by a set of physicochemical methods established that an increase in the concentration of the Tb3+ activator leads to its specific distribution: over gadolinium vacancies (VGd)''', by replacing Gd3+ ions and concentrating it at the boundaries of crystallites. It is noted that in this case, the morphology of crystallites changes, the short-range order of the structural unit of the lattice (Gd2O2) changes with the introduction of S2- ions into oxygen vacancies [VO]oo or the substitution of O2- anions, as a result of which the long-range order of the anionic sublattice is violated and the band gap decreases. At high concentrations of the photoluminescence activator Tb3+ 7 mol.%, radiation quenching does not occur due to the presence of the GdOF and TbOF phases. Variations of these effects with an increase in the Tb3+ concentration lead to an increase in the intensity of the emission in the green region of the 5D4->7Fj transitions and a decrease in the intensity of the emission in the blue region of the 5D3->7Fj transitions. Keywords: phosphor Gd2O2S : Tb(3-7 mol.%), real lattice structure, photoluminescence activator distribution, far infrared spectroscopy, Raman spectroscopy, XPS spectroscopy.