LaF3纳米晶体中 Sm3+/Eu3+能量传递效应的光谱学特性

摘要

The samples of LaF3 ∶ Sm3 + ,LaF3 ∶ Eu3 + and LaF3 ∶ Sm3 +/Eu3 + nanocrystals with high quality mono-disperse and uniform sizes were synthesized with hydrothermal method.The crystallographic phase, surface morphology,crystalline sizes and fluorescence properties of Sm3 +/Eu3 + sole-and co-doped nanocrys-tals were characterized with X-ray powder diffraction (XRD),transmission electron microscopy (TEM)and photoluminescence (PL)spectroscopic technique,respectively.The results of XRD and TEM show that the microstructure of the nanocrystals is hexagonal,with the average size about 40 nm.Using 442 nm He-Cd con-tinuous wave (CW)laser to pump the Sm3 + ions doped in the LaF3 ∶Sm3 +/Eu3 + nanocrystals,the typical flu-orescence emissions originating from the Eu3 + ions were observed in the emission spectra,and that the energy transfer from Sm3 + ions to Eu3 + ions was completed.The mechanism and efficiency of the energy transfer from Sm3 + ions to Eu3 + ions were investigated and discussed systematically based on the spectroscopic method.It is shown that the energy transfer of Sm3 + →Eu3 + is attributed to the cross-relaxation between the excited state 4 G 5/2 of Sm3 + ion and the 5 D 1 and 5 D 0 states of Eu3 + ion.Meanwhile,the intensities of the characteristic fluo-rescence emissions of Eu3 + ions become stronger and stronger with the increase of the Eu3 + doping concentra-tion,which suggest that the efficiency of energy transfer from Sm3 + ions to Eu3 + ions can be effectively im-proved by increasing the doping concentration of Eu3 + acceptor.%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 LaF3∶ Sm3+,LaF3：Eu3+和LaF3∶Sm3+／Eu3+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 Sm3+／Eu3+单掺和共掺 LaF3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 LaF3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 Sm3+／Eu3+共掺 LaF3样品中的 Sm3+时,在样品发射光谱中观测到了Eu3+的特征荧光发射谱线,实现了 Sm3+向 Eu3+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 Sm3+的4 G5／2激发态与 Eu3+的 5 D 1和5 D 0激发态之间的交叉驰豫所致,并且随着 Eu3+的掺杂浓度的增大,共掺 LaF3∶Sm3+／Eu3+样品的发射谱中的 Eu3+的特征荧光发射强度也随之增强,这说明增加受主 Eu3+的掺杂浓度能够有效地提高 Sm3+→Eu3+能量传递的效率。