Peculiarities of luminescence decay of Ce:LaF 3

Luminescence decay properties of crystalline LaF3 nanoparticles containing 12 % of Ce3+ ions collected at different stages of microwave hydrothermal treatment were studied. The microwave treatment has led to improvement of surface perturbed sites luminescence together with reducing PL decay time of regular sites apparently due to higher surface/volume ratio

Photodynamic Processes in Fluoride Crystals Doped with Ce3+

Integrated studies of photoelectric phenomena and their associated photodynamic processes in LiCaAlF6, LiLuF4, LiYF4, LiY0,5Lu0,5F4, SrAlF5 crystals doped with Ce3+ ions have been carried out using the combination of the methods of optical and dielectric spectroscopy. The numerical values of the basic parameters of photodynamic processes and their spectral dependence in 240 – 310 nm spectral range are evaluated. It has been shown that the most probable process, which leads to the photoionization of Ce3+ ions in LiYxLu1-xF4:Ce3+ (x=0; 0,5; 1) and LiCaAlF6:Ce3+ crystals, is excited-state absorption to the states of mixed configurations of Ce3+ ions localized near/in the conduction band of crystal

Photodynamic Processes in Fluoride Crystals Doped with Ce

Integrated studies of photoelectric phenomena and their associated photodynamic processes in LiCaAlF6, LiLuF4, LiYF4, LiY0,5Lu0,5F4, SrAlF5 crystals doped with Ce3+ ions have been carried out using the combination of the methods of optical and dielectric spectroscopy. The numerical values of the basic parameters of photodynamic processes and their spectral dependence in 240 – 310 nm spectral range are evaluated. It has been shown that the most probable process, which leads to the photoionization of Ce3+ ions in LiYxLu1-xF4:Ce3+ (x=0; 0,5; 1) and LiCaAlF6:Ce3+ crystals, is excited-state absorption to the states of mixed configurations of Ce3+ ions localized near/in the conduction band of crystal

LiY0.3Lu0.7F4: Ce3+,Pr3+ Mixed Crystal as a Perspective Up-Conversionally Pumped UV Active Medium

Investigation results of effective population of states of 5d-configuration of Ce3+ ions by energy transfer from Pr3+ ions in LiY0.3Lu0.7F4 (LYLF) crystals are discussed. The real concentrations of Pr3+ and Ce3+ ions in LYLF crystals are determined. Such parameters as excited 4f-5d state photoionization cross-section of Pr3+ ions, ground state cross-section of Ce3+ ions at 266 nm wavelengths and energy transfer coefficients of energy transfer from Pr3+ to Ce3+ ions were estimated. The results of pump-probe experiments on 5d-4f transitions of Ce3+ ions in LYLF crystals are presented. The optimal parameters for getting maximal gain on 5d-4f transitions of Ce3+ ions were determined by mathematical modeling

LiY

Investigation results of effective population of states of 5d-configuration of Ce3+ ions by energy transfer from Pr3+ ions in LiY0.3Lu0.7F4 (LYLF) crystals are discussed. The real concentrations of Pr3+ and Ce3+ ions in LYLF crystals are determined. Such parameters as excited 4f-5d state photoionization cross-section of Pr3+ ions, ground state cross-section of Ce3+ ions at 266 nm wavelengths and energy transfer coefficients of energy transfer from Pr3+ to Ce3+ ions were estimated. The results of pump-probe experiments on 5d-4f transitions of Ce3+ ions in LYLF crystals are presented. The optimal parameters for getting maximal gain on 5d-4f transitions of Ce3+ ions were determined by mathematical modeling

Luminescent thermometry based on Ba<inf>4</inf>Y<inf>3</inf>F<inf>17</inf>:Pr³⁺ and Ba<inf>4</inf>Y<inf>3</inf>F<inf>17</inf>:Pr³⁺,Yb³⁺ nanoparticles

© 2020 Elsevier Ltd and Techna Group S.r.l. New effective luminescence thermometers based on novel host Ba4Y3F17 doped with Pr3+ and Pr3+/Yb3+ in 80–320 K temperature range were studied. The absolute temperature sensitivity (Sa) of both Ba4Y3F17: Pr3+(0.1 mol %) and Ba4Y3F17: Pr3+(0.1 mol.%): Yb3+(10.0 mol.%)nanothermometers based on luminescence intensity ratio (LIR) between two Pr3+ emission bands (3P1-3H5 and 3P0-3H5) demonstrate a notable value (0.011 K−1 at 300 K) in the 200–320 K range. The Ba4Y3F17: Pr3+(0.1 mol.%): Yb3+(10.0 mol.%)nanothermometers based on LIR between 3P0→3H4 of Pr3+ and 2F5/2→ 2F7/2 of Yb3+ emission bands demonstrate high Sa into the 80–200 K range with maximal Sa = 0,0778 K−1 at 100 K. The stability of the phosphors was revealed by thermo-cycling experiments

Faraday isolator based on NTF crystal in critical orientation

The characteristics of a magneto-optical material promising for the development of Faraday isolators for high-power lasers - the Na0.37Tb0.63F2.26 (NTF) solid solution crystal with a negative value of optical anisotropy parameter - were investigated. The value of the optical anisotropy parameter ζNTF = -0.26 ± 0.02 was refined in model experiments on samples with increased absorption, and the value of the thermo-optical constant Q characterizing thermally induced depolarization was measured to be QNTF = (3.44 ± 0.4)·10-6 K-1. The negative value of ζ indicates that the depolarization resulting from stress-induced birefringence in this material is strongly dependent on orientation and ensures the presence of a critical orientation [C], with the use of which the magnitude of thermally induced depolarization in the Faraday isolator may be significantly reduced. The [C] orientation is determined by the parameter ζ; therefore, its accurate measurement is of particular importance. The investigation of Faraday isolators based on NTF crystals cut in [001] and [C] orientations demonstrated a significant advantage of the critical orientation. According to the measurement result, with the use of crystals with normal absorption, it is possible to develop a traditional (single element) Faraday isolator operating at room temperature and ensuring the isolation ratio of about 30 dB at the laser radiation power of ∼7 kW. This makes the NTF crystal one of the most prospective magneto-active media

Spatial anomalies in spectral-kinetic properties of Pr³⁺ - Doped LiY<inf>1-x</inf>Lu<inf>x</inf>F<inf>4</inf> mixed crystals

© 2020 We present the spectral-kinetic including excited state absorption spatial-dependent features of Pr3+ - doped LiY1-xLuxF4 mixed crystals grown by Bridgeman technique

Down-conversion luminescence of Yb³⁺ in novel Ba<inf>4</inf>Y<inf>3</inf>F<inf>17</inf>:Yb:Ce solid solution by excitation of Ce³⁺ in UV spectral range

© 2020 Elsevier B.V. The down-conversion luminescence under UV excitation was demonstrated in single-phase Ba4Y3F17 solid solution nanoparticles codoped with Ce3+/Yb3+. The complex photodynamic processes occurred in the samples including excited state absorption, excitons and color centers formation. The Yb doping suppressed the solarization effect. The efficiency of down-conversion from UV to near IR luminescence of Yb3+ appeared to be high due to Ce4+-Yb2+ charge transfer mechanism responsible for energy transfer between Ce3+ and Yb3+ ions. The direct measurements of down-conversion luminescence quantum yield by means of integrating sphere and calculations of energy transfer efficiency from luminescence spectra data were carried out. The down-conversion luminescence quantum yield reached the maximum value of about 1% for the sample with 0,1 mol.% of Ce3+ and 5,0 mol.% of Yb3+ ions contents, whereas energy transfer coefficient reached its maximum of about 6,3% for 0,05 mol.% of Ce3+ and 5,0 mol.% of Yb3+ ions