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采用水热合成法,在较低的温度下制备了分散性,均匀性良好的LaF_3:Sm~(3+),LaF_3:Eu~(3+)和LaF_3:Sm~(3+)/Eu~(3+)纳米晶体样品。通过X射线衍射(XRD),透射电子显微镜(TEM)和光致发光(PL)等手段,分别对Sm~(3+)/Eu~(3+)单掺和共掺LaF_3纳米晶体的物相,表面形貌,晶粒尺寸和荧光特性进行了表征。XRD和TEM检测结果显示,所制备的LaF_3纳米晶体呈六方晶体相,平均粒径在40 nm左右。当采用波长为442 nm的He-Cd连续激光器激发Sm~(3+)/Eu~(3+)共掺LaF3样品中的Sm~(3+)时,在样品发射光谱中观测到了Eu~(3+)的特征荧光发射谱线,实现了Sm~(3+)向Eu~(3+)的能量传递。采用光谱学研究方法讨论了能量传递的机理和效率。结果表明,能量传递过程是Sm~(3+)的~4G_(5/2)激发态与Eu~(3+)的~5D_1和~5D_0激发态之间的交叉驰豫所致,并且随着Eu~(3+)的掺杂浓度的增大,共掺LaF_3:Sm~(3+)/Eu~(3+)样品的发射谱中的Eu~(3+)的特征荧光发射强度也随之增强,这说明增加受主Eu~(3+)的掺杂浓度能够有效地提高Sm~(3+)→Eu~(3+)能量传递的效率。
La 3: Sm 3+, LaF 3: Eu 3+ and LaF 3: Sm 3+ / Eu ~ (3+) were prepared by hydrothermal method at low temperature with good homogeneity. (3+) nanocrystal sample. The phase of Sm 3+ / Eu 3+ doped and co-doped LaF 3 nanocrystals were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and photoluminescence (PL) Surface morphology, grain size and fluorescence characteristics were characterized. The results of XRD and TEM show that the prepared LaF_3 nanocrystals have a hexagonal crystal phase and the average particle size is about 40 nm. When Sm ~ (3+) in the Sm ~ (3 +) / Eu ~ (3+) codoped LaF3 sample was excited by a He-Cd continuous laser with a wavelength of 442 nm, Eu ~ ( 3+). The energy transfer from Sm 3+ to Eu 3+ was achieved. The mechanism and efficiency of energy transfer are discussed using spectroscopic methods. The results show that the energy transfer process is due to the cross-relaxation between the ~ 4G_ (5/2) excited states of Sm ~ (3+) and the excited states of ~ 5D_1 and ~ 5D_0 of Eu ~ (3+) The emission intensity of Eu 3+ in the emission spectrum of codoped LaF_3: Sm ~ (3 +) / Eu ~ (3+) samples also increases with the increase of Eu ~ (3+) doping concentration This shows that increasing the doping concentration of acceptor Eu 3+ can effectively improve the energy transfer efficiency of Sm 3+ → Eu 3+.