Complex defects in crystal scintillation materials and phosphors

The possibility of the existence of complex defects in pure and doped crystal phosphor discussed in work. The luminescent properties of mono- and nanocrystals of zinc tungstate, the powders of YAG with various compositions are studied. It is shown that the intrinsic defects, impurities, oxygen vacancies, the hydroxyl groups may be present in the structure of the complex defects (nanodefects). Nanodefects form during synthesis and have high efficiency of the transfer of excitation energy to the emission centres

Complex defects in crystal scintillation materials and phosphors

The possibility of the existence of complex defects in pure and doped crystal phosphor discussed in work. The luminescent properties of mono- and nanocrystals of zinc tungstate, the powders of YAG with various compositions are studied. It is shown that the intrinsic defects, impurities, oxygen vacancies, the hydroxyl groups may be present in the structure of the complex defects (nanodefects). Nanodefects form during synthesis and have high efficiency of the transfer of excitation energy to the emission centres

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

Luminescence decay kinetics of yttrium aluminium garnet phosphor at different temperature

The temperature dependence of the luminescence decay for a series of SDL YAG:Ce phosphors is investigated. Luminescence quenching excited by chip under heat-treatment is observed. The dependence of temperature on thermal luminescent intensity at elevated temperature (range from room temperature to 200°C) was tested. Noticeable luminescence quenching of SDL 2700 phosphor is observed at temperatures above 50°C, and by increasing temperature up to 200°C, the luminescence intensity decreases 5 times. Compare with sdl2700 phosphor, the temperature quenching of sdl3500 and sdl4000 phosphors is much lower. The investigated phosphors differ in the content of Gd3+. An explanation of the observed effects is proposed

Kinetic parameters of the uranium luminescence in Lif crystals

The results of researches with nanosecond time resolution of kinetic characteristics of luminescence buildup and decay in crystals LiF(U)-O at 300 K under action of both laser pulse with energy 3,68 eV and electron pulse with energy 300 keV have been presented. Influence of excite method on kinetic characteristics of uranium luminescence buildup and influence of uranium on kinetic characteristics of oxygen luminescence in crystal were establishe

Nanodefects in YAG: Ce phosphors

Since the mid-1990s, phosphors have played a key role in emerging solidstate white-lighting technologies that are based on combining a near-UV or blue solid-state light source with downconversion to longer wavelengths. Almost all of them used phosphorescreted a crystalline oxide, nitride, or oxynitride host that is appropriately doped with Gd, Ce or Eu. Activation of phosphors by rare earth elements, leads to the formation of defects in the lattice and due to the change in the luminescent properties. This paper presents the new original model of energy transfer in the YAG crystals, which is a good description of the possible luminescence transitions in crystals. The morphology, spectra and kinetics characteristics of the luminescence of industrial phosphor excited by electron and laser radiation were investigated. The obtained theoretical and practical data are good agreement with each other, and thus are of great interest for understanding the nature of luminescence

Effect of thermomechanical impacts on the deformation of thin polyimide films at uniaxial tension

Thermomechanical studies of the dependence of deformation on time (t) and temperature (T) for various static stresses in polyimide under uniaxial tension were carried out. Temporal deformation curves for static stresses in the range from 75 to 110 MPa consist of two stages: 1 - increase; 2 - exit to saturation, which is associated with a change in the nature of structural transformations of macromolecules, due to the action of the static stresses. An increase in temperature and voltage leads to an increase in the dependence e (Т). This is due to the intensification of the processes of structuring macromolecules with increasing temperature and are supplemented by processes of breaking bonds between macromolecules, which increase the strain rate. Experimental data are described in terms of exponential and linear models

Study of the influence of the electron irradiation dose on the deformation of Mylar films taking into account the processes of destruction and crosslinking

Experimental studies of the dependence of the deformation [epsilon] on the dose of electron irradiation D taking into account the processes of destruction and crosslinking for films of the Mylar type have been carried out. It was obtained that the dependence of [epsilon] on D for the process of cross-linking is described by a linear and destruction by an exponential function

Study of deformation dependence on time in polyethylene terephthalate for different static loads and irradiation doses

Complex experiments were conducted on deformation dependence on time for different static loads and irradiation doses in polyethylene terephthalate. Curves of time (t) dependence of deformation (?) show a significant change in the behavior of the material after irradiation. The obtained dependence curves of on t for both non-irradiated and irradiated materials are satisfactorily described by cascade-probability model

Investigation of Mechanical Properties of Polyimide- Polyethyl-eneterephthalate System

The study of the physico-mechanical properties of new composite materials based on polyimide (PI) and polyethyleneterephthalate (PET) was carried out. Dependences of σ from ε for different concentrations of the second component and irradiation doses were measured. The experimental data are described satisfactorily by the exponential cascadeprobabilistic model