| In the21st century, white light emitting diode (WLED) is a remarkable lighting source because it possesses such excellent performance as high luminescence efficiency, long life time, low power consumption, and environment friendly, and so on. Now, there are two approaches to obtain WLED:UV LED+RGB phosphors; Blue LED+yellow phosphors. The red phosphor is one oT mnost important in RGB phosphors. But the efficiency of the commercial Y2O2S:Eu3+red phosphor is less than that of the green and blue phosphors. In addition, sulfide-based phosphors are chemically unstable in atmosphere and not environmentally friendly. Therefore, the development of new red phosphors is an important task in industry and subject of academic circles.In the paper, a novel solvothermal route has been developed to synthesize mondispersed and different mophologiesof Eu-doped CaTiO3phosphors, using a mixture of ethylene glycol (EG) and ethylenediamine (EDA). The phosphors were characterized by X-ray diffraciton (XRD), scanning electron microscope (SEM) and fluorescence spectrophotometer(PL). The SEM revealed the magic-column spherical, magic-cube spherical and polyhedral shaped and good distribution of the phosphors synthesized by the mixture of ethylene glycol and ethanediamine. The morphology could be modulated by the temperature, time and solvent ratio. The CaTiO3:Eu3+phosphors showed the maximum emission wavelength was at617.6nm under the near-ultraviolet excitation (398.4nm). The optimal concentration gives the highest PL intensity of CaTiO3of Eu3+is3%. The PL intensity of CaTO3:Eu3+synthesized by solvothermal method was much higher than the solid solid-state method. Moreover, the powders prepared from magic-column spherical phosphors are beneficial for packing in white light LED manufacturing because of the uniform morphology, average particle size and monodisperse structre.Therefore, magic-column spherical CaTiO3:Eu3+is a promising red phosphor under near ultraviolet excitation for various applications.In order to improve titanate series phosphors, the Zn2TiO4:Eu3+phosphors were synthesized by the evaporation-induced self-assembly method. The FESEM images showed that the nanosphere of the Zn2Ti04:Eu3+phosphors are prepared. The crystalline Zn2Ti04:Eu3+phosphors showed the optimal excitation wavelength was466nm. The emission weaks from575to720nm and the maximum emission wavelength was at614nm. The optimized Eu doping concentration was found to be20mol%for the emission intensity reached the top. The Zn2Ti04:Eu3+phosphors have a higher fluorescence intensity and color rendering index by the comparison with commercial CaS red phosphors The phosphor obtained by our experiments could find extensive applications in high-efficient WLEDs.To extend the application of Eu-doped Zn2Ti04luminescent material, we design a novel fluorescent sensor system for environmental use based on luminescent mesoporous Eu-doped Zn2Ti04and ZnTiO3material which has been fabricated by the evaporation-induced self-assembly method using Pluronic P123as structure directing agents. The luminescent mesoporous material is pure cubic-phase ZnTiO3and Zn2Ti04. The phosphors were characterized by BET, TEM and PL. It has a large specific surface area, narrow pore size distribution, high luminescent performance, excellent luminescent sensing performance, effective removal ability and the change of visible red fluorescence for the heavy metal ions. Moreover, the ZnTiO3and Zn2Ti04:Eu3+material has an intrinsic selectivity for the Cu2+ions, and it also can be reused and show the stimuli-responsive controlled release behavior due to adding into nitric acid. In addition, the Zn2Ti04:Eu3+materials have a higher intensity, the internal quantum efficiency of the Zn2Ti04:Eu3+material are74.3%, and it also has tried to be applied in a facile microfluidic device to remove the heavy-metal ions. |
PDF Full Text Request