Mo^(6+)掺杂NaYF_(4):Yb^(3+),Ho^(3+)纳米颗粒的上转换性能研究

Research on Upconversion Properties of NaYF_(4):Yb^(3+),Ho^(3+) Nanoparticles Doped with Mo^(6+) Ions

采用热分解法制备了不同摩尔比的Mo^(6+)-NaYF_(4):Yb^(3+),Ho^(3+)上转换纳米颗粒(UCNPs),并用X射线衍射仪(XRD)、傅里叶变换红外光谱仪(FT-IR)、场发射扫描电子显微镜(FE-SEM)与荧光分光光度计(FS)等对样品的性能进行表征,以探究Mo^(6+)掺杂对NaYF_(4):Yb^(3+),Ho^(3+)的发光效率、结构和形貌的影响。结果表明,制得的UCNPs为β相NaYF_(4),其分散性良好,粒径分布均匀;MoO_(3)浓度≥12.5%(摩尔分数)时,UCNPs结构已非纯β-NaYF_(4);在980 nm激光仪照射下,UCNPs发射出两束可见光(542 nm的绿光与649 nm的红光)以及一束750 nm的近红外光;钼源为MoO_(3)或(NH_(4))_(6)Mo_(7)O_(24)·4H_(2)O,Mo^(6+)的最佳掺杂浓度均为2.5%,较未掺杂Mo^(6+)的样品,绿光强度分别增大了11倍与15倍,红光强度分别增大了7.2倍与3.4倍;UCNPs的红、绿光发光均为双光子过程,Mo^(6+)掺杂并未影响NaYF_(4):Yb^(3+),Ho^(3+)纳米颗粒的上转换(UC)发光机制。

In order to investigate the influence of Mo^(6+) ions doping on luminescent efficiency and structure and morphology of NaYF_(4):Yb^(3+),Ho^(3+), thermal decomposition method was selected to prepare NaYF_(4):Yb^(3+),Er^(3+) upconversion nanoparticles(UCNPs) with different molar concentration in this paper. Then the samples were characterized by X-ray diffraction(XRD) and fourier transform-infrared(FT-IR), field emission-scanning electron microscope(FE-SEM) and fluorescence spectrophotometer(FS), respectively. The results showed that β-phase NaYF_(4) UCNPs were obtained with good dispersion and uniform particle size. When MoO_(3) concentration over 12.5%, the structure of UCNPs isn’t pure β-NaYF_(4). Under the excitation of 980 nm laser, two beams of visible light with wavelengths of 649 nm(red emission) and 542 nm(green emission) and the beam of near-infrared light with wavelength of 750 nm are emitted from UCNPs.Compared to Mo^(6+)-free sample, the best doping concentration of Mo^(6+) ions that originated from MoO_(3) or(NH_(4))_(6)Mo_(7)O_(24)·4 H_(2)O is 2.5% Mo^(6+)-sample, which enhanced by 11 fold and 15 fold of green emission, 7.2 fold and 3.4 fold of red emission, respectively. The red and green emissions of UCNPs are two-processes and the UC mechanism of NaYF_(4):Yb^(3+),Ho^(3+) nanoparticles has not affected by Mo^(6+) ions doping.