Распределение катионов Tb-=SUP=-3+-=/SUP=- и Eu-=SUP=-3+-=/SUP=- в решетке C-Gd-=SUB=-2-=/SUB=-O-=SUB=-3-=/SUB=- по данным спектров фотолюминесценции и дальнего ИК

In this work, we investigated the features of the photoluminescence of C-Gd2(1-x)TbxEuxO3 luminophores at x = 1.0 and 2.5 mol%, which are associated with the distribution of Tb3+ and Eu3+ activator ions over the centrosymmetric C3i and noncentrosymmetric C2 positions of cations in the bixbyite lattice, as well as in the positions at the boundaries crystallites CS. We studied the phase transformations of the samples, changes in the morphology of crystallites, photoluminescence spectra, and spectra of the far infrared region 50–600 cm–1 with changes in the annealing modes of the initial products of the sol – gel synthesis Gd2(1 – x)TbxEux(OH)y(CO3)z · n(H2O) at temperatures of 900 and 1200oC in air and hydrogen. Correlations have been established between changes in the characteristics of the samples and the parameters of their annealing. Based on the analysis of these correlations, the redistribution of activators over the indicated cation positions was determined, and a model was proposed for identifying infrared absorption bands in accordance with the localization of activators along the cationic sublattices C3i and C2.

Influence of interstitial UO22+ doping on the valence control of Eu and energy transfer to substitutional Eu3+ and Sm3+ in SrBPO5

Controlling valence mixing of Eu3+/Eu2+ and energy transfer between activator ions in solid solution is an important direction to improve efficiency and specificity of phosphors. In this work, structural and...

Peculiar Structural Effects in Pure and Doped Functional Single Crystals of Complex Compositions

Results of a detailed structural characterization of nominally pure and doped single crystals of scheelite, eulytin, and perovskite families obtained by melt methods were considered and analyzed. The influence of growth and post-growth annealing conditions on actual compositions of crystals is shown. The reasons for the coloration of the crystals are explained. A change in crystal symmetry due to crystal–chemical and growth reasons is considered. The use of structural analysis and X-ray absorption spectroscopy is substantiated to reveal the role of activator ions in the formation of statistical and local structures, respectively. A relationship between the distribution of activator ions over crystallographic sites and photoluminescent parameters of materials is established, which allows selecting optimal systems for the application. The combined results of studying single-crystal compounds of other classes (huntite, sillenite, whitlockite, garnet, tetragonal bronzes) allow formulating and summarizing structural effects that appeared in the systems and caused by various factors and, in many cases, due to the local environment of cations. A principal difference in the structural behavior of solid solutions and doped compounds is shown. The methodology developed for single-crystal samples of complex compositions can be recommended for the systematic structural studies of functional materials of different compositions.

Doping homogeneity in co-doped materials investigated at different length scales

Doping homogeneity is important for the properties of co-doped phosphors, as it can affect the energy transfer between sensitizer and activator ions.