Luminescence characteristics of Xe2Cl excimer molecules under pumping the dense Xe—CCl4gas mixtures with a pulsed electron beam

AbstractNanophosphors in the amorphous state are first obtained via pulsed electron beam evaporation of targets made of polycrystalline phosphors with the compositions Ca_2M_8(SiO_4)_6O_2:Eu (M = Y and Gd) and Ca_2La_8(GeO_4)_6O_2:Eu with the structure of oxyapatite. Reduction of ions Eu^3+ → Eu^2+ in the electron beam is found. Modification of the Raman scattering (RS) spectra of the samples in the case of a decrease in the size of the particles from bulk to a nanosized state is found. The change in the forbidden band width E _ g of the samples in the case of transition from a bulk powder to an NP is considered. The spectral and luminescence characteristics of the samples in the polycrystalline and nanoamorphous states are studied. It is shown that, in the case of transition to nanosamples, the ligand field around Eu^2+ changes. This may be due to the violation of the translational symmetry in the NP. The bond between the 4 f and 5 d electrons weakens. Degeneracy of the ^2 e _ g level appears. Presumably, the reduction of ions Eu^3+ → Eu^2+ in the electron beam due to the breaking of the Si(Ge)–O bond in the process of evaporation of the samples and capture of the released electron by the Eu^3+ ions is found.

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New amorphous nanophosphors obtained by evaporation of silicates and germanates REE

Pure and Applied Chemistry ◽

10.1515/pac-2016-1118 ◽

2017 ◽

Vol 89 (10) ◽

pp. 1505-1520

Author(s):

Mikhail G. Zuev ◽

Vladislav G. Il’ves ◽

Sergey Yu. Sokovnin ◽

Andrei A. Vasin ◽

Elena Yu. Zhuravleva

Keyword(s):

Electron Beam ◽

Laser Excitation ◽

Electron Beam Evaporation ◽

Scanning Calorimetry ◽

Radiation Reduction ◽

Bulk State ◽

Pulsed Electron Beam ◽

First Time ◽

Luminescence Characteristics ◽

Raman And Ir Spectra

Abstract Amorphous nanophosphors have been produced by pulsed electron beam evaporation of bulk phosphors of rare earth elements (REE) silicates and germanates with oxyapatite structure activated with europium. The processes of crystallization of amorphous nanopowders (NP) have been studied by differential scanning calorimetry and thermogravimetry (40–1400°C) methods. A modification of the Raman and IR spectra of the samples was found when the particle size decreased from bulk to nanostate due to insignificant polymerization of Si(Ge)O4 tetrahedra. The spectral and luminescence characteristics of the bulk samples as well as nanoamorphous samples have been examined. It was established that Eu3+ forms two types of optical centers. Upon the transition of Sr2Gd8(SiO4)6O2:Eu3+ phosphor from bulk state to nanostate during laser excitation, the luminescence intensity of Eu3+ ions increases 10 times. Blue and white amorphous nanophosphors have been obtained for the first time by evaporation of Ca2M8(SiO4)6O2:Eu (M=Y, Gd) and Ca2La8(GeO4)O2:Eu phosphors. Radiation reduction of ions Eu3+→Eu2+ in electron beam has been presumably found.

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