Contollable Synthesis Of Lanthanide Ions Doped Oxyfluorides Nanocrystals And Investigation Of Their Mid-infrared Luminescence

2~5 μm mid-infrared fluorescence and laser, covering the important transparent atmospheric transmission window and numerous molecular characteristic spectral lines, have important applications and wide prospects in both military and civilian areas. So far, among many materals and methods in achieving 2~5 μm mid-infrared laser, the rare-earth ions doped glass materials, glass fiber and single-crystals materials have been one of the most promising and most significant mid-infrared solid gain medium. However, the conventional mid-infrared solid gain medium reached a bottleneck state at present, due to the harsh requirements of realizing efficient mid-infrared fluorescence and laser. Compared with conventional mid-infrared materials, crystals-glass composite materials combine the advantages of both crystals and glass. It could open a brand new field for the research of novel mid-infrared fluorescence and laser materials, meanwhile, as its luminescence center, the mid-infrared fluorescence nanocrystals have gained much attention. Therefore, the exploration of mid-infrared fluorescence nanocrystals with good monodispersity and highly efficient luminescence performance plays a vital role in the realization of transparent crystals-glass composite materials with highly efficient mid-infrared emission. Oxyfluorides materals combining the excellent advantages of fluoride glasses in optical properties and oxide glasses in mechanical properties, become ideal optical host materials for mid-infrared emission. Hence, this dissertation was aimed to synthesize the Er3+-doping oxyfluorides nanocrystal materials, exploring and researching the Er3+:2.7 μm mid-infrared fluorescence property in the oxyfluorides host system.This dissertation choose lanthanide oxyfluorides LnOF(Ln= La, Gd, Y) nanocrystals as research basis, for their low phonon energy, good physical and chemical stability. Using the urea as homogeneous precipitating agent and the potassium fluoride(KF) as fluorine source, we prepared Er3+-doped LnOF(Ln= La, Gd, Y) nanocrystals with diverse morphologies and size via a simple co-precipitation route and sequent heat-treatment. Their morphologies and size distribution were studied in detail. The results show that granular LaOF:Er3+ nanoparticles have an average size of ~30 nm; Gd OF:Er3+ nanocrystals present a morphorlogy of nano-riced shape with length ~300 nm and width ~100 nm; YOF:Er3+ nanocrystals present a morphorlogy of quasi-spherical shape with an average size ~80 nm.We have investigated the phase formation and transformation of LnOF nanocrystals in the calcination process via the XRD results and TG-DSC results. In addition, the continuous heat treatment is benefit for better crystallinity and effectively removal of OH-. We have also studied the mid-infrared luminescence performance of Er3+ in LnOF(Ln= La, Gd, Y) nanocrystals through the photoluminescence(PL) spectra. In addition, we have discussed about the effect of continuous heat treatment on the luminescence performance of Er3+, and compared the Er3+:2.7 μm mid-infrared fluorescence property in different LnOF(Ln= La, Gd, Y) nanocrystal hosts. The results suggested that strong Er3+:2.7 μm mid-infrared emission, arising from 4I11/2 to 4I13/2 transition, have realized among these calcination products in three LnOF(Ln= La, Gd, Y) system, besides, both in GdOF:Er3+ nanocrystals and YOF:Er3+ nanocrystals have realized intense Er3+:2.7 μm mid-infrared emission for the first time.