https://repozytorium.ukw.edu.pl///handle/item/52 Fri, 17 Apr 2026 03:11:09 GMT 2026-04-17T03:11:09Z https://repozytorium.ukw.edu.pl///handle/item/8256 Optical and Electron Paramagnetic Resonance Study of the Ce3+ Luminescent Centers in Lu2SiO5:Ce Single Crystalline Films Laguta, Valentin; Nikl, Martin; Trubitsyn, Mykhailo; Gorbenko, Vitaliy; Zorenko, Tetiana; Witkiewicz-Łukaszek, Sandra; Fedorov, Alexandr; Zorenko, Yuriy The work presents the results of optical and EPR investigations of Ce3+ incorporation into Lu2SiO5 single crystalline films (LSO:Ce SCFs), grown using the liquid phase epitaxy method. It also examines the conversion of Ce valence state as a result of the LSO:Ce SCF thermal treatment in reducing and oxygen-rich atmospheres. The EPR study revealed the presence of only one type of Ce3+ center (Ce1), corresponding to the localization of Ce3+ ions in sevenfold coordinated positions within the Lu2SiO5 host. No spectra of Ce2 centers (sixfold coordinated Ce3+ positions) were detected in the LSO:Ce SCF films, indicating their negligibly small concentration. Hightemperature annealing of the as grown films in air reduces the concentration of Ce3+ ions to a level undetectable by EPR, due to the Ce3+ → Ce4+ conversion. In contrast, thermal treatment in a 95%N2 + 5%H2 reducing atmosphere results in the opposite Ce4+ → Ce3+ conversion, substantially increasing the concentration of Ce3+. The oxidation/reduction treatment and Ce³⁺/Ce⁴⁺ valence state changing lead to notable variations in the scintillation light yield and decay kinetics of the LSO:Ce SCFs, offering a method to tune their scintillation figure of merit. Thu, 01 Jan 2026 00:00:00 GMT https://repozytorium.ukw.edu.pl///handle/item/8256 2026-01-01T00:00:00Z https://repozytorium.ukw.edu.pl///handle/item/8255 Raman spectroscopy and high-resolution luminescence spectroscopy of Ce3+ doped Tb3Al5O12 single crystalline film phosphors grown onto Gd3Al2.5Ga2.5O12 and Y3Al5O12 substrates Syrotych, Yurii; Rzeczkowski, Maciej; Radomski, Piotr; Gorbenko, Vitaliy; Zorenko, Yuriy; Runka, Tomasz We present the results of a study on Raman and high-resolution luminescence spectroscopy of Ce3+-doped Tb3Al5O12 single crystalline films (SCFs) grown by the liquid phase epitaxy (LPE) method onto Y3Al5O12 and Gd3Al2.5Ga2.5O12 single crystal (SC) substrates. The Ce3+-doped Tb3Al5O12 films exhibit a strong Ce3+ 5d–4f emission band centred at 560 nm when excited around 488 nm in the vicinity of the 4f–5d absorption band of Ce3+ and the 4f–4f absorption bands of Tb3+ ions in the visible range. To avoid overlapping with this luminescence, Raman spectra were recorded using a 785 nm excitation wavelength. The lattice mismatch between the Tb3Al5O12:Ce films and the Y3Al5O12 and Gd3Al2.5Ga2.5O12 substrates was found to be +0.53% and −1.32%, respectively. The film grown on the Gd3Al2.5Ga2.5O12 substrate exhibits negative and higher residual stress compared to its counterpart grown onto the Y3Al5O12 substrate. The observed shifts in the positions of the Raman modes for the two epitaxial structures correlate with the differences in lattice constants between the films and their respective substrates. High-resolution luminescence spectra recorded at 488 nm and 785 nm excitation wavelengths reveal 5d–4f and 4f–4f electronic transitions of Ce3+ ions and lanthanide trace impurities, respectively. Thu, 01 Jan 2026 00:00:00 GMT https://repozytorium.ukw.edu.pl///handle/item/8255 2026-01-01T00:00:00Z https://repozytorium.ukw.edu.pl///handle/item/8146 Color converters for white LEDs using liquid phase epitaxy growth method Markovskyi, Anton; Gorbenko, Vitaliy; Zorenko, Tetiana; Fedorov, A.; Zorenko, Yuriy The development of innovative high-power lighting sources is urgently required to design and investigate the new high structural quality and high-temperature stable converters in the form of single crystals and single crystalline films. This research deals with the growth and investigation of structural, luminescence, and photoconversion properties (color coordinates, color temperature and color rendering index) of the single crystalline films of Ce3+ doped (Lu, Y, Tb, Gd)3Al5O12 garnets, grown using the Liquid Phase Epitaxy method onto undoped Y3Al5O12 substrates. The combination of Ce3+ doped Lu3Al5O12, Y3Al5O12, Tb3Al5O12, Gd2.9Lu0.1Al5O12 film converter with respective thickness with commercial blue LED allows for obtaining green-yellow-orange-emitting pc-WLEDs. The application of the mentioned film converters results in the formation of four basic trends on the color diagram depending on the thickness of the converter. Mon, 01 Jan 2024 00:00:00 GMT https://repozytorium.ukw.edu.pl///handle/item/8146 2024-01-01T00:00:00Z https://repozytorium.ukw.edu.pl///handle/item/8145 Luminescence and photoconversion properties of Ce-doped Ca3Sc2Si3O12 crystal Shakhno, Anna; Gieszczyk, W.; Bilski, P.; Witkiewicz-Łukaszek, Sandra; Zorenko, Tetiana; Cieszko, Mieczysław; Szczepański, Zbigniew; Kotlov, A.; Zorenko, Yuriy This work is dedicated to investigation of the luminescent properties of the prospective photoconversion material based on the crystal of Ce3+ doped Ca3Sc2Si3O12 (CSSG) garnet. The GSSG:Ce crystal was grown using the micro-pulling-down (μPD) method. The CSSG:Ce crystal exhibited an intensive photoluminescence (PL) emission band with two sub-bands peaked at 504 and 545 nm, corresponding to 5d-4f (2F5/2;7/2) transitions. Furthermore, we have investigated also the formation of cerium multicenters in the GSSG:Ce crystal using analyses of the structure of Ce3+ photoluminescence emission and excitation spectra under excitation of the luminescence of this crystal by synchrotron radiation. The formation of Ce3+-multicenters in CSSG:Ce garnet is caused by the local inhomogeneity of the dodecahedral sites of garnet lattice due to localization of the hetero-valent Sc3+ and Si4+ cations in the octahedral and tetrahedral positions of the garnet host. The existence of Ce3+ multicenters resulted in a significant enhancement of the Ce3+ emission band in the red range and improving the performance of conventional YAG:Ce phosphor. The next task of our work was to evaluate the possibility of application of the GSSG:Ce crystal as a light phosphor-converter (pc) for white light-emitting diodes (WLEDs). In the frame of this task, we have successfully developed a prototype of WLED by employing the CSSG:Ce crystal as a phosphor-converter (pc) with blue 450 emitting LED as well as investigated the color characteristics of this pc-WLED. Mon, 01 Jan 2024 00:00:00 GMT https://repozytorium.ukw.edu.pl///handle/item/8145 2024-01-01T00:00:00Z