16056-77-2Relevant articles and documents
Photon upconversion in Yb3+-Tb3+ and Yb3+-Eu3+ activated core/shell nanoparticles with dual-band excitation
Dong, Hao,Sun, Ling-Dong,Wang, Ye-Fu,Xiao, Jia-Wen,Tu, Datao,Chen, Xueyuan,Yan, Chun-Hua
, p. 4186 - 4192 (2016)
Exploring novel lanthanide-activated upconversion nanoparticles with distinctive spectral fingerprints and emission lifetimes has long been a great concern for extended optical applications. Herein, we report the study of photon upconversion emissions in Yb3+-Tb3+ and Yb3+-Eu3+ activated nanoparticles with near-infrared excitation. In these nanoparticles, a high content of Yb3+ is required for the simultaneous excitation of two Yb3+ ions, yielding a Yb3+ dimer with a higher excited energy to upconvert photons onto Tb3+ and Eu3+. The optimum doping concentration of Yb3+ ions for Yb3+-Tb3+ and Yb3+-Eu3+ pairs was determined to be 80% and 60%, respectively, which are much higher than that of Yb3+-Er3+/Tm3+ pairs. Notably, the upconversion emission lifetime of the as-prepared nanoparticles was prolonged to 2.3 ms (Tb3+) and 4.0 ms (Eu3+), respectively. Through the epitaxial growth of a Nd3+ doped shell layer, the upconversion emissions of Tb3+ and Eu3+ were intensified 25-fold. At the same time, an extra excitation band in the shorter near-infrared region from Nd3+ at 808 nm was achieved. Moreover, the emissions of Tm3+ were employed to compensate for those of Tb3+ and Eu3+ for multicolor emissions. These results highlight the upconversion emissions of Tb3+ and Eu3+ for potential multicolor imaging and multiplexed detection applications.
Upconversion luminescence in sub-10 nm β-NaGdF4:Yb3+,Er3+ nanoparticles: An improved synthesis in anhydrous ionic liquids
Tessitore, Gabriella,Mudring, Anja-Verena,Kr?mer, Karl W.
, p. 34784 - 34792 (2019)
Sub-10 nm β-NaGdF4:18% Yb3+,2% Er3+ nanoparticles were synthesized in ethylene glycol and various ionic liquids under microwave heating. The products were characterized by powder X-ray diffraction, electron microscopy, and upconversion (UC) luminescence spectroscopy. After Yb3+ excitation at 970 nm, Er3+ ions are excited by energy transfer upconversion and show the typical green and red emission bands. The UC luminescence intensity was optimized with respect to reactant concentrations, solvents, and reaction temperature and time. The strongest UC emission was achieved for sub-20 nm core-shell nanoparticles which were obtained in the ionic liquid diallyldimethylammonium bis(trifluoromethanesulfonyl)amide from a two-step synthesis without intermediate separation. Strictly anhydrous reaction conditions, a high fluoride/rare earth ion ratio, and a core-shell structure are important parameters to obtain highly luminescent nanoparticles. These conditions reduce non-radiative losses due to defects and high energy acceptor modes of surface ligands. A low power excitation of the core-shell particles by 70 mW at 970 nm results in an impressive UC emission intensity of 0.12% compared to the bulk sample.
Comparative studies of structure, spectroscopic properties and intensity parameters of tetragonal rare earth vanadate nanophosphors doped with Eu(III)
Grzyb, Tomasz,Szczeszak, Agata,Shyichuk, Andrii,Moura, Renaldo Tenorio,Neto, Albano Neto Carneiro,Andrzejewska, Nina,Malta, Oscar Loureiro,Lis, Stefan
, p. 459 - 472 (2018)
Hydrothermal method was applied in order to synthesize nanocrystalline YVO4, LaVO4 and GdVO4 materials doped with Eu3+ ions. The conditions of synthesis were chosen to allow control of the process based on precipitation reaction in an autoclave, at elevated temperature and pressure. The prepared materials crystallized as single phase spherical-like nanocrystals of the tetragonal I41/amd structure. The average size of the particles was in the range of 7–10 nm in the YVO4- and GdVO4-based products and about 32 nm when LaVO4 was the host compound. The excitation spectra of the materials prepared revealed a broad and intense band in the UV region. The band resulted from charge transfer phenomena: excitation of the VO43+ groups was followed by the energy transfer to Eu3+ ions. Intense, red emission of the samples was a result of electronic transitions in Eu3+ dopant ions. The theoretical Judd-Ofelt intensity parameters Ωλ, obtained using the novel approach to the calculation of Eu-O bond stretching force constant and subsequently charge factors, were compared to the experimental Ωλ. Forced electric dipole part of Ωλ was calculated from scratch (using Eu3+ coordination geometry in REVO4 from DFT calculations), while a single parameter in the dynamic coupling part was fitted to the experimental data. The issues related to the force constant calculation are discussed. Crucial influence of crystal lattice distortions on Ωλ and Eu3+ emission intensities of the materials was shown.
Preparation of REFeAsO1-xFx (R E=Sm and Gd) superconductors at a relatively low temperature
Cui,Chen,Cheng,Yang,Wang,Li,Zhao
, p. 449 - 452 (2011/07/07)
A series of the SmFeAsO1-xFx and GdFeAsO 1-xFx (x=0.05, 0.1, 0.15, 0.2, 0.25) samples have been prepared using nano-scaled ReF3 as the fluorine resource at a relatively low temperature. The samples have been sintered at 1100 and 1120 °C for SmFeAsO1-xFx and GdFeAsO1-xF x, respectively. These temperatures are at least 5060° lower than other previous reports. All of the so-prepared samples possess a tetragonal ZrCuSiAs-type structure. Dramatically supression of the lattice parameters and increase in Tc proved that this low temperature process was more effective to introduce fluorine into REFeAsO. Superconducting transition appeared at 39.5 K for SmFeAsO1-xFx with x=0.05 and at 22 K for GdFeAsO1-xFx with x=0.1. The highest Tc was detected to be 54 K in SmFeAsO0.8F0.2 and 40.2 K in GdFeAsO0.75F0.25. The use of the nano-scaled ReF3 compounds has improved the efficiency of the present low temperature method in synthesizing the fluorine-doped iron-based superconductors.
