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This paper reports the spectroscopic properties of praseodymium-doped potassium lutetium double phosphates, KLuP2O7:Pr3+(1%). Spectra of photoluminescence (PL), PL excitation, X-ray excited luminescence and pulse cathodoluminescence, thermally stimulated luminescence were measured. KLuP2O7:Pr3+ showed Pr3+ emission connected both with high intensity interconfigurational 4f15d1→4f2 transitions (UV bands in region of 250-320 nm), intraconfigurational 4f2→4f2 transitions (weak lines in vision spectral region) and Stocks defect-related luminescence. Upon both UV intra-center and band-to-band excitation with ionizing radiation, emission spectra of KLuP2O7:Pr3+ are dominated by Pr3+ interconfigurational 4f15d1→4f2 radiative transitions. Luminescence decay kinetics measurements established decay time τ≈19 ns at room temperature. The study of thermally stimulated luminescence demonstrates effective light storage. Parameters of charge carriers' traps were calculated: ΔE1 = 1.1 eV (for peak at 352 K) and ΔE2 = 1.3 eV (for peak at 388 K). © 2020 American Institute of Physics Inc. All rights reserved. ; The work was partially supported by the Ministry of Education and Science of The Russian Federation (through the basic part of the government mandate), Act 211 Government of the Russian Federation (contract N? 02.A03.21.0006). The time-resolved X-ray excited measurements were performed at the Shared research center SSTRC based on the NovoFEL/VEPP-4 - VEPP-2000 facilities at Budker Institute of Nuclear Physics (Siberian Branch of Russian Academy of Sciences, Novosibirsk, Russia) while using experimental equipment funded by RFMEFI62119X0022 project. Authors thank Prof. Marco Bettinelli (University of Verona, Italy) for providing research samples, Dr. Sergey Omelkov (University of Tartu, Estonia) for assistant in PCL measurements and Dr. Konstantin Ivanovskikh (UrFU, Yekaterinburg, Russia) for fruitful discussions.

The paper presents a comparative analysis of RKTF crystals (full name single crystals Rb 2 KTiOF 5 ), and RKTF + e crystals, single crystals irradiated on a cyclotron by fast electrons Rb 2 KTiOF 5 . The crystals were grown by slow solidification method. The study was conducted at a temperature from 7 to 400 K for various types of optical and radiation effects. Spectra of photoluminescence (PL) and X-ray excited luminescence (XRL) in region of 1.5-5.5 eV, time-resolved pulse cathode-luminescence (PCL) spectra, the temperature depending of the XRL, luminescence decay kinetics were studied. Single crystal RKTF are transparent from microwave up to the edge of the long-wave fundamental absorption (near UV range). We detected three luminescence bands for RKTF, in the visible spectral region, that were attributed to radiative annihilation of intrinsic excitons (2.25 eV), recombinaion-type luminescence (2.1 eV) and luminescence of higher TiOF 5 complexes (1.9 eV), for all emission bands characterized by great (∼1.5-1.8 eV) Stokes shift. The exponential component with lifetime of approximately 19 μs was found in the PCL decay kinetics at 2.25 eV. In the crystal RKTF + e we detected new luminescence bands 2.6 eV and 3.2 eV and the disappearance of the RKTF luminescence bands. Stokes shift of the band 3.2 eV of the RKTF + e crystal is much smaller and is equal to 0.7 eV. Excitation of the band 3.2 eV occurs in the field of crystal transparency, which indicates the defective nature of the glow. PCL decay kinetics at 2.0 and 2.5 eV has a complex nature and consists of at least two components with a life time of 0.5 ms and 6 ms, that significantly more in comparison with RKTF. Irradiation by fast electrons of crystals Rb 2 KTiOF 5 led to entirely new optical properties and suppression of self-luminescence of the crystals. © Published under licence by IOP Publishing Ltd. ; This work has been partially supported by the Ministry of Education and Science of the Russian Federation – basic part of the government mandate (project No. 3.8302.2017/8.9) and Act 211 Government of the Russian Federation (contract No. 02.A03.21.0006, the Center of Excellence "Radiation and Nuclear Technologies") and COST Action TD1401 "FAST". The authors thank to Dr. S. Omelkov (University of Tartu, Estonia) for help in PCL experiments and M. Sarychev (UrFU) for support in low temperature measurements.

This paper reports the spectroscopic properties of praseodymium-doped phosphates, borates and silicates. Polycrystalline samples of Pr3+-doped KLuP2O7, Li6Y(BO3)3, LiY6O5(BO3)3, LiSrPO4, Sr9Sc(PO4)7, K3Lu(PO4)2, K3LuSi2O7 were synthesized using a solid state reaction. Spectra of X-ray excited luminescence and its decay kinetics were measured. Studied samples demonstrate interconfigurational 5d-4f, intraconfigurational 4f-4f transitions and defect-related luminescence. Comparative analysis of spectroscopic properties and application perspectives is presented. © 2020 American Institute of Physics Inc. All rights reserved. ; The work was partially supported by the Ministry of Science and Higher Education of the Russian Federation (through the basic part of the government mandate, project No. FEUZ-2020-0060), Act 211 Government of the Russian Federation (contract № 02.A03.21.0006) and RFMEFI62117X0012 project. The time-resolved X-ray excited measurements were performed at the Shared research center SSTRC based on the NovoFEL/VEPP-4 -VEPP-2000 facilities at Budker Institute of Nuclear Physics (Siberian Branch of Russian Academy of Sciences, Novosibirsk, Russia) while using experimental equipment funded by RFMEFI62119X0022 project. The authors are grateful to S. Omelkov (University of Tartu, Estonia) for assisting in the measurement using a pulsed electron beam.

Spectra of photoluminescence (PL) and X-ray excited luminescence (XRL) in region of 1.5-5.0 eV, PL excitation spectra (2.8-5.8 eV), PL decay kinetics were measured in Gd2O3 crystals doped both with Er3+ and Zn2+ ions. Synchrotron radiation (VEPP-3 storage ring, Novosibirsk, Russia) were used for XRL measurements. PL spectra were studied at room temperature and T= 88 K under excitation with energy Eexc: a) in fundamental absorption region (Eexc≥Eg); b) in intracenter excitation region (Eexc

The photo- and thermally- stimulated luminescence of Gd2O3 and Gd2O3:Zn nanostructured powders has been investigated at 295 and 90 K. Optically active impurities and intrinsic defects in the host lattice have been detected. The kinetics parameters of the charge trapping centers (order of kinetics, activation energy, frequency factor) were determined. The nature of defect states and their role in the processes of the energy relaxation are discussed. © 2016 The Authors. ; This work was supported by the Ministry of Education and Science of Russia, the Grain-in-Aid Agreement no. 14.581.21.0002, September 29, 2014 (the unique identifier RFMEFI58114X0002) in the frame of the Federal Aim Program Research and Development in Priority Directions of the Science and Technology Complex of Russia for 2014-2020. The part of results was obtained within the framework of the Act 211 of Government of the Russian Federation, contract no 02.A03.21.0006 and carried out in the framework of state assignment of Russian Federation Ministry of Science and Education (3.1016.2014/K). The author L. Spallino acknowledges for the financial support of the RFBR (Russian Foundation for Basic Research) 2016/2018 (Project No 16-32-60063).

Paper reports the effect of a 10 keV, 110 keV and 10 MeV electron beam irradiation on optical and luminescence properties of LiBaAlF6 (LBAF) single crystals at 10, 90, and 293 K. Five absorption bands at 2.0, 3.2, 4.3, 4.9 and 5.5 eV were revealed in irradiated crystals in the energy range of 1.2–9.5 eV. Several PL emission bands (1.7–1.8, 2.2 and 2.5–3.5 eV) related to defects were found in the luminescence spectra at room temperature, while only one luminescence band at E = 2.2 eV appears at T = 90 K in LBAF crystals after a 10 MeV electron bombardment. The PL excitation spectra and time-response for these emission bands were studied at 10, 90, and 293 K. Thermoluminescence (TL) of irradiated crystals was studied in the temperature range of 90–740 K. New TL glow peaks at 166, 530 and 670 K were revealed and their parameters were determined. Temperature dependence of relative photoluminescence yield recorded monitoring emission at the 1.87 and 2.23 eV in the temperature range from 130 to 450 K, were fitted using five quenching processes related to TL glow peaks revealed in our research. Significant similarity in the manifestation of radiation-induced defects for LBAF and previously studied LiBaF3 single crystals is noted. The effect of an electron beam irradiation on optical and luminescence properties of LBAF single crystals and possible origin of the radiation defects were discussed. © 2017 Elsevier B.V. ; This work was partially supported by the Ministry of Education and Science of the Russian Federation (Contract No.02.A03.21.0006) (the basic part of the government mandate), the Center of Excellence "Radiation and Nuclear Technologies" (Competitiveness Enhancement Program of Ural Federal University, Russia), HASYLAB DESY (Project No.20110843), Estonian Research Council (projects IUT2-26 and PUT1081). We are grateful to Ludmila Isaenko for providing the crystals examined and Eugene Vasilchenko for recording a high-temperature TL glow curve.

Luminescent characteristics of K3Lu(PO4)2:Pr3+ (1 and 5 mol.%) microcrystalline powders, a promising optical material for scintillation applications, were investigated using various experimental techniques. The material shows emission features connected with both high intensity interconfigurational 4f15d→4f2 transitions (broad UV emission bands) and intraconfigurational 4f2→4f2 transitions (weak emission lines in the visible range). The output of X-ray excited 4f15d→4f2 emission of Pr3+ increases with a temperature rise from 90 K to room temperature and higher depending on the Pr3+ ions concentration. The high 5% concentration of Pr3+ ions is found to be favourable for the stabilization of a monoclinic phase (P21/m space group) over a trigonal one (P3‾ space group) while emission properties of the material reveal that a phase transition occurs at higher temperatures. Decay kinetics of Pr3+ 4f15d→4f2 emission are recorded upon excitation with high repetition rate X-ray synchrotron excitation and pulse cathode ray excitation. Issues related to a non-exponential decay of luminescence and presence of slow decay components are discussed in terms of energy transfer dynamics. The presence of defects was revealed with thermoluminescence measurements and these are suggested to be the mainly responsible for delayed recombination of charge carriers on the Pr3+ 4f15d states. Some peculiarities of host-to-impurity energy transfer are discussed. © 2020 Elsevier B.V. ; The work was partially supported by the Ministry of Science and Higher Education of the Russian Federation (through the basic part of the government mandate, project No. FEUZ-2020-0060), Act 211 Government of the Russian Federation (contract № 02.A03.21.0006), STSM grant from COST Action TD1401 ″FAST" as well as by Estonian Research Council (project PRG629) and Estonian Center of Excellence in Research "Advanced materials and high-technology devices for sustainable energetics, sensorics and nanoelectronics" TK141 (project No. 2014-2020.4.01.15-0011) by the ERDF ...

The luminescent characteristics of the double phosphate KLuP2O7 doped with Pr3+ ions, a promising optical material for scintillator applications, were investigated using various experimental spectroscopic techniques. KLuP2O7:Pr3+ shows Pr3+ emission associated with interconfigurational 4f15d1→4f2 transitions located in the UV range (250–320 nm), intraconfigurational 4f2→4f2 transitions (weak lines in the visible spectral range) and defect-related luminescence. The light output of X-ray or cathode ray excited Pr3+ 4f15d1→4f2 luminescence is found to be nearly independent of temperature in the range of 90–400 K. The output of pulsed cathode luminescence shows thermal quenching above 450 K characterized by an activation energy of about 0.5 eV. Upon excitation with pulsed cathode rays or high-frequency (~8 MHz) X-ray synchrotron radiation, the luminescence decay kinetics of Pr3+ 4f15d1→4f2 transitions are dominated by a decay component with lifetime of about 20 ns. An additional slower decay component with lifetime of 75 ns was observed upon cathode ray excitation and was shown to result from delayed host-to-impurity energy transfer. The latter, in turn, originates from re-trapping of charge carriers at defect-related traps whose presence was demonstrated by thermoluminescence measurements. Parameters of the trapping centers were estimated. Peculiarities of host-to-impurity energy transfer are analysed and discussed. © 2020 Elsevier B.V. ; The work was partially supported by the Ministry of Science and Higher Education of the Russian Federation (through the basic part of the government mandate, Project No. FEUZ-2020-0060), Act 211 Government of the Russian Federation (contract № 02.A03.21.0006 ) and RFMEFI62117X0012 project as well as by Estonian Research Council (project PRG629 ) and Estonian Centre of Excellence in Research "Advanced materials and high-technology devices for sustainable energetics, sensorics and nanoelectronics" TK141 (2014-2020.4.01.15-0011) . E. Trofimva is thankful for support by European ...

Luminescent transparent nanoceramics were obtained by thermobaric treatment (TBT) of magnesium aluminium spinel nanopowder. The morphological features were studied by scanning electron microscopy combined with X-ray powder diffraction. Obtained ceramics do not have any agglomerates and pores larger than 100 nm. Crystallites have a high size uniformity. An increase in the lattice constant of nanoceramics compared to the initial powder is observed. Under the TBT, a decrease in the region of coherent scattering due to elastic deformation of crystallites is found. The absence of cracks, large pores, nanosize grains, and high size uniformity reduce light loss in the material, increasing its transparency. Point defects were characterized by photoluminescence and electron spin resonance (ESR) methods. The glow in the 1.8 eV band is caused by the presence of Ti3+ impurity ions. An abnormally wide peak with a maximum at 2.4 eV in the photoluminescence spectrum is recorded. This signal is a superposition of the Mn2+ ions emission bands and oxygen vacancies (F and F+ centres). In the ESR spectrum, signals from impurity ions of iron, titanium, and manganese, as well as an intense signal at g = 2.005 associated with oxygen vacancies in nanoceramics were detected. © 2018 Institute of Physics Publishing. All rights reserved. ; The work was done as a part of the government task (№3.1485.2017/4.6) of the Ministry of Education and Science of the Russian Federation and was carried out in accordance with the scientific and research plans and state assignment of the Institute of Solid State Chemistry of the Ural Branch of the Russian Academy of Sciences (AAAA-A16-116122810212-5). ; et al.;NT-MDT Spectrum Instruments;Ostec-ArtTool Ltd.;Promenergolab LLC;Russian Foundation for Basic Research;Taylor and Francis Group