Luminescence spectra of YAG:Се phosphors synthesized in a field of radiation

The paper presents the measurement results of the luminescence band shape for YAG phosphors upon photoexcitation. It is shown that the position and FWHM does not depend on the excitation technique, but it depends on the phosphor prehistory. The observed difference is assumed to be due to the difference in the structure of nanodefects in phosphors synthesized under different conditions

Luminescence of F2 and F3 + centres in LiF crystals irradiated with 12 MeV 12C ions

Dependences of the nanohardness and photoluminescence of F 2 and F 3 + centers on the depth in LiF crystals irradiated with 12 MeV 12 C ions to fluences 10 10 -10 15 ions/cm 2 were studied using laser scanning confocal microscopy, luminescent spectroscopy, and the nanoindentation method. The nanohardness measurements showed a significant hardening effect at the end of the ion run with the dominant contribution of defects formed by the mechanism of elastic collisions. The observed attenuation of the luminescence intensity at high fluences is associated with the intense nucleation of dislocations as traps for aggregate color centers.The work was carried out within the framework of the grant GF AP05134257 of the Ministry of Education and Science of the Republic of Kazakhstan; Institute of Solid State Physics, University of Latvia as the Center of Excellence has received funding from the European Union’s Horizon 2020 Framework Programme H2020-WIDESPREAD-01-2016-2017-TeamingPhase2 under grant agreement No. 739508, project CAMART

Thermal stability of color centers in LiF crystals: dependence on radiation type and dose

Accumulation of radiation defects at irradiation is the complex result of consecutive and mutually independent events: formation of primary pair, spatial separation of its components and their transformation into stable ones under experimental conditions [1]..

Thermal stability of color centers in LiF crystals: dependence on radiation type and dose

Accumulation of radiation defects at irradiation is the complex result of consecutive and mutually independent events: formation of primary pair, spatial separation of its components and their transformation into stable ones under experimental conditions [1]..

Transition levels of acceptor impurities in ZnO crystals by DFT-LCAO calculations

This research was partly supported by the Kazakhstan Science Project № AP05134367«Synthesis of nanocrystals in track templates of SiO2/Si for sensory, nano-and optoelectronic applications» and Latvian Super Cluster (LASC), installed in the Institute of Solid State Physics (ISSP) of the University of Latvia. Authors are indebted to D. Gryaznov, A. Popov and A. Dauletbekova for stimulating discussions.Large scale ab-initio calculations are carried out to study the charge state transition levels of nitrogen and phosphorus impurity defects in zinc oxide crystals using the DFT-LCAO approximation as implemented into the CRYSTAL computer code. It is shown that at a high concentration of defects (close location of defects) their formation energy is underestimated due to a significant delocalization of the charge within the supercell. After inclusion the energy offset correction and defect-defective interaction, the formation energy is improved, in a comparison with that calculated in a large supercell. The optical transition levels obtained by a direct calculation confirm the experimental observation: nitrogen and phosphorus impurities are deep acceptor centers with large formation energy in a charged state and, therefore, cannot serve as the effective source of hole charge. The obtained results are in good agreement with the previous theoretical work, in which other calculation methods were used, and are capable of qualitatively describing the energy characteristics of the charged defects.University of Latvia; Institute of Solid State Physics, Chinese Academy of Sciences; Institute of Solid State Physics, University of Latvia as the Center of Excellence has received funding from the European Union’s Horizon 2020 Framework Programme H2020-WIDESPREAD-01-2016-2017-TeamingPhase2 under grant agreement No. 739508, project CAMART

Structure and Luminescence of YAG:Ce, Gd, Ga Ceramics Synthesized Radiation Assistedmethod

The work shows the possibility of radiation synthesis based on YAG:Ce ceramics. Synthesis was carried out by sintering samples from oxide powders in the field of high-energy electron flow. The lattice structure of synthesized samples of YAG:Ce and YAGG:Ce ceramics was compared with standards.The work was carried out within the framework of the grant AP08052050 of the Ministry of Education and Science of the Republic of Kazakhstan. This research was supported by Tomsk Polytechnic University CE Program

Structural and luminescent characteristics of YAG phosphors synthesized in the radiation field

YAG:Ce, YAGG:Ce ceramics were obtained by sintering the oxide powders in the radiation field. The results of investigations of the structure, composition and luminescence of ceramics are presented. The luminescence characteristics of powders exactly correspond to the phosphors luminescence used in practice obtained by solid-state synthesis methods. It has been established that in the used radiation exposure modes the main factor determining the efficiency of the synthesis is the ionization density

Structural and luminescent characteristics of YAG phosphors synthesized in the radiation field

YAG:Ce, YAGG:Ce ceramics were obtained by sintering the oxide powders in the radiation field. The results of investigations of the structure, composition and luminescence of ceramics are presented. The luminescence characteristics of powders exactly correspond to the phosphors luminescence used in practice obtained by solid-state synthesis methods. It has been established that in the used radiation exposure modes the main factor determining the efficiency of the synthesis is the ionization density

Мікромеханічні властивості кристалів Gd3Ga5O12, опромінених швидкими важкими іонами

У даній статті наведені результати досліджень оптичного поглинання та механічної поведінки монокристалів Gd3Ga5O12 (GGG), підданих дії швидких іонів 84 Kr при флюенсах від 1013 до 1014 іон/см2. Установлено, що спектри оптичного поглинання GGG, вирощених за допомогою методу Чохральського, мають чіткі вузькі лінії в УФ-спектрі, що можна віднести до переходів 4f-4f у Gd3+. Було виявлено чіткі зміни від базового стану 6S 7/2 до станів 6P, 6J і 6D в катіоні Gd3+. Неочікувана смуга поглинання також була виявлена при 350 нм, ймовірно, в результаті ненавмисного забруднення Ca. Після впливу іонів край основного поглинання зміщується приблизно на 30 нм у бік більш довгохвильової ділянки спектру. Тести на твердість показали ефект пом’якшення після впливу іонів, пов’язаний з аморфізацією матеріалу.This study investigated the optical absorption and mechanical behavior of Gd3Ga5O12 (GGG) single crystals exposed to fast 84 Kr ions at fluences ranging from 1013 to 1014 ion/cm2. We observed that the optical absorption spectra of GGGs grown using the Czochralski method feature distinct narrow lines in the UV spectrum, attributable to the 4f-4f transitions in Gd3+. Clear changes were identified from the 6S 7/2 base state to the 6P, 6J, and 6D states within the Gd3+ cation. An unexpected absorption band was also detected at 350 nm, likely resulting from unintentional Ca contamination. After ion exposure, the fundamental absorption edge shifted by approximately 30 nm towards the longer-wavelength section of the spectrum. Our hardness tests indicated a softening effect post-ion exposure, possibly linked to ion-triggered amorphization