0000000000905604
AUTHOR
D. Sugak
Stable and transient color centers in Gd3Ga5O12 crystals
The work is devoted to investigation of stable color centers (CC) that are created in Gd3Ga5O12 (GGG) crystals under irradiation with γ-quanta (E = 1.25 MeV, D = 105 Gy ) as well as transient CC created in the crystals under irradiation with pulsed electron beam (E = 0.25 MeV, pulse duration 10 ns, fluence 1012 cm-2, time interval of registration 0-500 ns). On the basis of the performed study of optical absorption spectra of the as-grown and irradiated crystals it was established the correlation between a defect subsystem of as-grown crystals and a type of CC induced by radiation in the crystals. The role of Ca2+ dopant ions in the processes of CC formation is examined. Models of the stable…
Transient color centers in GGG crystals
Electron pulse induced absorption and their decay kinetics have been investigated in samples of GGG crystals with different starting absorption spectra. It is shown that for all samples there appears a wide transient absorption (TA) band with two maxima in the region 14,000-17,000 v cm m 1 and 22,000-26,000 v cm m 1 . TA decay kinetics measurements in 14,000 v cm m 1 and 22,000 v cm m 1 are two-exponential (with half-time order several tens and several hundreds ns). Analyzing the obtained results, we can suppose that low and high energy TA bands are connected with the F + (or O m ) and F transient color centers (TCC) respectively.
EPR and optical spectroscopy of neutron-irradiated Gd3Ga5O12 single crystals
Abstract In this paper, we have performed comparative analysis of EPR, optical absorption (OA) and luminescence spectra for a series of Gd3Ga5O12 (GGG) single crystals irradiated with fast neutrons with fluencies varied from 1016 to 1020n/cm2. In a crystal irradiated with the maximum neutron fluence, the EPR spectra demonstrated the formation of several paramagnetic defects. In particular, EPR spectrum shows a strong resonance at (effective) g ≈ 1.4 with practically isotropic behavior in the crystal rotation around the [1 1 1] direction (magnetic field being perpendicular to [1 1 1]) and several weaker lines in the g ≈ 1.1–2.6 region, which show more pronounced angular dependences. While th…
Optical investigation of the OH− groups in the LiNbO3 doped by copper
Doping ions and OH− groups absorption bands spatial profiles were investigated for the case of congruent LiNbO3 single crystal grown by Czochralski technique. Doping was performed after the crystal...
Luminescence Properties and Decay Kinetics of Mn2+ and Eu3+ Co-Dopant Ions In MgGa2O4 Ceramics
A. Luchechko gratefully acknowledges a grant from the Institute of Physics PAS for a research visit to the institute, while A.I. Popov has been supported by project LZP-2018/1-0214 from the Latvian Council of Science.
Optical detection of paramagnetic centres in activated oxyfluoride glass-ceramics
Electron paramagnetic resonance (EPR), magnetic circular dichroism (MCD) and EPR detected via MCD (MCD-EPR) investigations have been performed on rare-earth activated oxyfluoride glasses and glass-ceramics. Er3+, Gd3+, and Mn2+ activators in oxyfluoride glass-ceramics show paramagnetic MCD behaviour and the MCD-EPR has been detected. The results of the MCD-EPR measurements for the Er-doped oxyfluoride glass-ceramics showed that Er3+ ions in the CaF2 crystallites in these ceramics embed only in the cubic symmetry environment, similarly to the previous observations of cubic Gd3+ centres in the glass-ceramics containing CaF2. Finally, the correlation of optics and paramagnetic centres is discu…
Transient and stable color centers in pure and Cu-doped LiNbO3
The present work is devoted to investigation of stable and transient color centers that are induced by radiation and temperature in pure and Cu-doped LiNbO 3 single crystals. The transient changes of absorption of the crystals induced by pulsed electron beam (E=0.25 MeV) are studied in 0-5000 ns time range, as well as stable changes of absorption induced by reducing annealing and irradiation with γ-quanta, high energy electrons or fast reactor neutrons.