Silica glass-ceramics containing highly crystalline LaF 3 :Eu 3+ nanocrystals (NCs) were successfully prepared at a relatively low temperature of 950 °C within a short time of 10 min by Spark Plasma Sintering. The LaF 3 :Eu 3+ NCs were not only well retained without interfacial reaction occurring between LaF 3 :Eu 3+ NCs and silica matrix phases, but also homogeneously dispersed in glass matrix. The luminescence peaks located within reddish-orange spectral scope were registered and identified as the intra-configurational 4 f 6 - 4 f 6 transitions originated from Eu 3+ optically active ions ( 5 D 0 → 7 F J , J = 0–4). By adopting the LaF 3 :Eu 3+ glass-ceramic as color convertor, the fabricated LED shows excellent reddish emission.
In this experiment, sodium carboxymethyl cellulose (CMC) was used as raw material, rare earth chloride was used as inorganic nano luminescent material to prepare a series of lanthanide rare earth ions-doped composite materials. The photoluminescent materials were prepared via in-situ chemical deposition of rare earth ions onto CMC surface with the help of carboxyl groups contained on the surface of CMC. The structure, fluorescence properties, surface morphology, surface elements, crystalline structure and thermal stability of CMC before and after surface modification were characterized by FT-IR spectra (FTIR), photoluminescence spectra (PL), field emission scanning electron microscope (FESEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and thermal gravimetric analyses (TGA), respectively. The results showed that CMC/LaF 3 :Eu 3+ composites were successfully prepared, and the fluorescence intensity can be organically controlled by the reaction temperature, doping ratio and doping concentration of rare earth ions. The method has mild reaction conditions, facile process without expensive material equipment. Moreover, the as-prepared transparent anti-counterfeiting film possessed good fluorescence intensity, transparency and excellent mechanical properties, which can be used for large-scale functional packaging films.
The LaF3 nanoparticles doped with different concentration Eu3+ ions are prepared by a simple and low temperature synthetic route. The nanoparticles with the size of about 3.5 nm are roughly spherical and monodisperse. The emission of Eu3+ ions is sensitized
through pyromellitic acid bonded onto the surface of nanoparticles. The structure, morphology, photoluminescence properties and fluorescence dynamics are studied systemically. The results show that the sensitized nanoparticles have a broad absorption band in the UV domain and high asymmetry
radio, and enhanced Eu3+ luminescence by “antenna effect” of ligands. The excited state lifetimes of sensitized nanoparticles are longer than those of un-sensitized nanoparticles and corresponding europium complexes.
Improved red emission in polyvinylpyrrolidone (PVP)-coated hollow LaF3:Eu3+ nanoparticles by introducing Li+ ions was found for the first time via a one-step template-free hydrothermal method. The hollow formation can be attributed to self-recrystallization and a local Ostwald ripening thermodynamic process. Pores were clearly seen and widely distributed in all LaF3 nanoparticles. The introduction of Li+ ions did not introduce new crystalline phases and resulted in little change in size and morphology of the LaF3 nanoparticles. The main diffraction peaks were found to shift slightly with the Li+ doping concentrations, which indicates that Li+ changes the crystal field environment of Eu3+. The excitation and red emission intensity both doubled when codoped with 7 mol% Li+ ions. The widely distributed pores and improved luminescence properties of our nanoparticles facilitated the construction of new nanocomposites for novel biological applications.
危险品化学品经营许可证（带存储）