Monoclinic LaPO4 nanostructures with uniform rod shape have been successfully synthesized by a simple sol-gel method.The procedure involves formation of homogeneous,transparent,metal-citrate-EDTA gel precursors,follow...Monoclinic LaPO4 nanostructures with uniform rod shape have been successfully synthesized by a simple sol-gel method.The procedure involves formation of homogeneous,transparent,metal-citrate-EDTA gel precursors,followed by calcination to promote thermal decomposition of the gel precursors to yield the LaPO4 nanoparticles.Their morphologies and structures were characterized by XRD,TEM,TG-DSC and HRTEM.The results indicate that single monoclinic phase LaPO4 nanorods are readily obtained at 800 ℃ within 3 h.Furthermore,photoluminescence(PL) characterization of the Eu3+-doped LaPO4 nanocrystals was carried out.The effects of calcination temperatures and Eu3+ doping content on the PL properties were elaborated in detail.Room-temperature photoluminescence(PL) characterization reveals that the optical brightness as well as the intensity ratio of 5D0-7F1 to 5D0-7F2 is highly dependent on the calcination temperature,and the Eu0.05La0.95PO4 nanophosphor shows the relatively promising PL performance with the most intense emission.展开更多
Monoclinic and hexagonal LaPO4：5 mol.%Eu3＋ phosphors were synthesized with merely adjusting pH values of solutions by a hydrothermal method at the same synthesis temperature. The microstructure, morphology and photo...Monoclinic and hexagonal LaPO4：5 mol.%Eu3＋ phosphors were synthesized with merely adjusting pH values of solutions by a hydrothermal method at the same synthesis temperature. The microstructure, morphology and photoluminescence of Eu3＋-doped LaPO4, which were influenced by different preparation conditions, were characterized by X-ray diffraction （XRD）, scanning electron microscopy （SEM）, Fourier transform infrared spectroscopy （FT-IR）, Raman spectroscopy and luminescence spectroscopy, respec-tively. The specimen showed monoclinic structure in strong acid solution, however, it changed into hexagonal structure in weak acid solution and strong alkali solution. The monoclinic LaPO4：Eu3＋ showed the longest length to diameter ratio, which was attributed to the preferential growth of[-112]. The monoclinic specimen exhibited a slight red shift in infrared spectra, Raman band positions and charge transfer （CT） compared with hexagonal specimens. Moreover, the calculated results of grain sizes, lattice parameters, full width at half maximum in Raman patterns and emission integral intensity were in good agreement with analysis results. The mono-clinic specimen showed the maximal absolute luminescence quantum yield （0.4） and the second lifetimeτ2 （0.52 ms）, which was ac-cordant with red-orange emission in CIE. The5D0→7F1 occupied a dominate position in hexagonal specimens, which indicated that more Eu3＋ in the hexagonal structure were occupied inversion center of symmetry sites.展开更多
基金Project(50972166) supported by the National Natural Science Foundation of ChinaProject supported by the Scientific Research Foundation for the Returned Overseas Chinese Scholars,State Education Ministry,China
文摘Monoclinic LaPO4 nanostructures with uniform rod shape have been successfully synthesized by a simple sol-gel method.The procedure involves formation of homogeneous,transparent,metal-citrate-EDTA gel precursors,followed by calcination to promote thermal decomposition of the gel precursors to yield the LaPO4 nanoparticles.Their morphologies and structures were characterized by XRD,TEM,TG-DSC and HRTEM.The results indicate that single monoclinic phase LaPO4 nanorods are readily obtained at 800 ℃ within 3 h.Furthermore,photoluminescence(PL) characterization of the Eu3+-doped LaPO4 nanocrystals was carried out.The effects of calcination temperatures and Eu3+ doping content on the PL properties were elaborated in detail.Room-temperature photoluminescence(PL) characterization reveals that the optical brightness as well as the intensity ratio of 5D0-7F1 to 5D0-7F2 is highly dependent on the calcination temperature,and the Eu0.05La0.95PO4 nanophosphor shows the relatively promising PL performance with the most intense emission.
基金supported by the National Natural Science Foundation of China(51172217)
文摘Monoclinic and hexagonal LaPO4：5 mol.%Eu3＋ phosphors were synthesized with merely adjusting pH values of solutions by a hydrothermal method at the same synthesis temperature. The microstructure, morphology and photoluminescence of Eu3＋-doped LaPO4, which were influenced by different preparation conditions, were characterized by X-ray diffraction （XRD）, scanning electron microscopy （SEM）, Fourier transform infrared spectroscopy （FT-IR）, Raman spectroscopy and luminescence spectroscopy, respec-tively. The specimen showed monoclinic structure in strong acid solution, however, it changed into hexagonal structure in weak acid solution and strong alkali solution. The monoclinic LaPO4：Eu3＋ showed the longest length to diameter ratio, which was attributed to the preferential growth of[-112]. The monoclinic specimen exhibited a slight red shift in infrared spectra, Raman band positions and charge transfer （CT） compared with hexagonal specimens. Moreover, the calculated results of grain sizes, lattice parameters, full width at half maximum in Raman patterns and emission integral intensity were in good agreement with analysis results. The mono-clinic specimen showed the maximal absolute luminescence quantum yield （0.4） and the second lifetimeτ2 （0.52 ms）, which was ac-cordant with red-orange emission in CIE. The5D0→7F1 occupied a dominate position in hexagonal specimens, which indicated that more Eu3＋ in the hexagonal structure were occupied inversion center of symmetry sites.
