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231 results on '"Nejezchleb, Karel"'

23. Intrinsic and [Ce.sup.3+]--related luminescence of single crystals and single crystalline films of YAP perovskites: new results

Author

Zorenko, Yuriy, Gorbenko, Vitaliy, Voloshinovskii, Anatoliy, Vistovskii, Vitaliy, Nikl, Martin, Mihokova, Eva, and Nejezchleb, Karel

Subjects
Luminescence -- Evaluation, Crystals -- Atomic properties, Crystals -- Optical properties, Perovskite -- Atomic properties, Perovskite -- Optical properties, Cerium -- Atomic properties, Business, Electronics, Electronics and electrical industries
Abstract

Intrinsic emission of undoped and [Ce.sup.3+] doped single crystal (SC) and single crystalline films (SCF) of YAl[O.sub.3] (YAP) was studied using the time-resolved luminescence spectroscopy under excitation by pulsed X-ray and synchrotron radiation. In contrast to YAP SCF, the YAP bulk SC are characterized by the presence of Y-in-Al-positions antisite defects (AD) and large concentration of vacancy-type defects (VD) of different types, which contribute to the intrinsic emission of YAP SC. Such type defects are centers of the luminescence in the UV (6.0-4.75 eV) and near UV (4.75-2.2 eV) ranges, overlapping with the Ce absorption and emission bands. Furthermore, they can give rise to shallow trapping centers as well. For this reason the AD and VD can strongly influence the scintillation properties of YAP:Ce SC. Specifically, the decay kinetics of the Ce emission in YAP:Ce SC, besides the fast component (23.3 [+ or -] 3.5 ns) related to radiative 5d-4f transition of Ce ions, contains also two slow components in the hundred ns and [mu]s ranges, which are due to the AD and VD-related traps. The advantages of scintillators based on YAP:Ce SCF, namely faster scintillation decay and lower contribution of slow components in the total light yield, can be achieved due to the absence of above mentioned bulk crystal defects. Index Terms--Antisite and vacancy type defects, intrinsic luminescence, scintillators, YAP single crystals and single crystalline films.

Published
2008

24. Luminescence and ESR study of irregular [Ce.sup.3+] ions in LuAG:Ce single crystals

Author

Babin, Vladimir, Laguta, Valentin V., Makhov, Aleksei, Nejezchleb, Karel, Nikl, Martin, and Zazubovich, Svetlana

Subjects
Luminescence -- Evaluation, Crystals -- Atomic properties, Crystals -- Optical properties, Cerium -- Atomic properties, Cerium -- Optical properties, Business, Electronics, Electronics and electrical industries
Abstract

Luminescence of new irregular [Ce.sup.3+]-related centers: the unperturbed and perturbed [Ce.sup.3+] ions located in [Al.sup.3+] sites and the [Ce.sup.3+.sub.LU] ions perturbed by [Lu.sup.3+.sub.Al] ions was found. The systematic study of these centers by means of the ESR and luminescence methods and their influence on scintillation characteristics was performed. The structure and symmetry of the irregular [Ce.sup.3+] centers was established and their spectral characteristics were explained. Index Terms--Antisite defects, ESR, luminescence, scintillators.

Published
2008

43. Three-frequency Nd:YAG laser for dental treatment

Author

Dostálová, Tatjána, primary, Kadlecova, Martina, primary, Jelínková, Helena, primary, Němec, Michal, primary, Šulc, Jan, primary, Nejezchleb, Karel, primary, Škoda, Václav, primary, Kapitch, Nickalai, primary, Fibrich, Martin, primary, and Bradna, Pavel, primary

Published
2018
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