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用水热法合成了稀土掺杂的立方相、六方相NaYF4:Eu3+和正交相YF3:Eu3+纳米晶体.从立方相到六方相NaYF4:Eu3+仅仅通过改变前驱物的浓度来实现,而改变RE3+/NaF的比例,则得到正交相YF3:Eu3+纳米晶体.通过分析XRD,TEM和荧光探针离子Eu3+的荧光发射谱,详细研究了前驱物浓度控制的纳米晶体的生长机理,并用光谱学手段评价了结晶的好坏.为了进一步完善结晶程度和除去纳米晶体表面的羟基团,将立方相、六方相NaYF4:Eu3+和正交相YF3:Eu3+纳米晶体退火处理,发现六方相NaYF4:Eu3+结构是一种热力学稳定相,而立方相NaYF4:Eu3+和正交相YF3:Eu3+则容易相变为YOF:Eu3+,退火之后的样品均表现出一定程度的团聚.将Tb3+离子掺杂于3种氟化物基质中,研究其荧光特性,发现在YF3:Tb3+纳米晶体中,晶场劈裂明显,甚至在室温下,可以清晰的观察到斯托克斯劈裂.这进一步揭示了减少NaF的量,可以有效地控制生长速率,导致结晶发育良好.
The rare earth-doped cubic phase, hexagonal NaYF4: Eu3 + and the orthorhombic YF3: Eu3 + nanocrystals were synthesized by hydrothermal method.From the cubic phase to the hexagonal phase, NaYF4: Eu3 + is only achieved by changing the concentration of the precursor, while changing the RE3 + NaF ratio, the phase YF3: Eu3 + nanocrystals were obtained.The mechanism of the growth of nanocrystals controlled by the precursor concentrations was studied in detail by analyzing the XRD, TEM and fluorescence emission spectra of Eu3 + In order to further improve the degree of crystallization and remove the hydroxyl groups on the surface of the nanocrystals, the cubic phase, the hexagonal NaYF4: Eu3 + and the orthogonal phase YF3: Eu3 + nanocrystals were annealed to find that the hexagonal NaYF4: Eu3 + structure is one And the thermodynamic stable phase, while the cubic phase NaYF4: Eu3 + and the orthogonal phase YF3: Eu3 + are easy to phase change to YOF: Eu3 +, the samples after annealing showed a certain degree of agglomeration. Tb3 + ions were doped in three kinds of fluoride matrix , The fluorescence characteristics were studied and it was found that the crystal field cleavage was conspicuous in the YF3: Tb3 + nanocrystals, and the Stokes splitting can be clearly observed even at room temperature, which further reveals that reducing the amount of NaF can be effective To control students Rate, leading to the development of good crystallinity.