State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, PR China.
Inorg Chem. 2012 Oct 15;51(20):11106-16. doi: 10.1021/ic301662c. Epub 2012 Sep 28.
A series of LaOF:Ln(3+) (Ln = Eu, Tb, Sm, Dy, Tm, and/or Ho) nanocrystals with good dispersion have been successfully prepared by the hydrothermal method followed a heat-treatment process. Under ultraviolet radiation and low-voltage electron beam excitation, the LaOF:Ln(3+) nanocrystals show the characteristic f-f emissions of Ln(3+) (Ln = Eu, Tb, Sm, Dy, Tm, or Ho) and give red, blue-green, orange, yellow, blue, and green emission, respectively. Moreover, there exists simultaneous luminescence of Tb(3+), Eu(3+), Sm(3+), Dy(3+), Tm(3+), or Ho(3+) individually when codoping them in the single-phase LaOF host (for example, LaOF:Tb(3+), Eu(3+)/Sm(3+); LaOF:Tm(3+), Dy(3+)/Ho(3+); LaOF:Tm(3+), Ho(3+), Eu(3+) systems), which is beneficial to tune the emission colors. Under low-voltage electron beam excitation, a variety of colors can be efficiently adjusted by varying the doping ions and the doping concentration, making these materials have potential applications in field-emission display devices. More importantly, the energy transfer from Tm(3+) to Ho(3+) in the LaOF:Tm(3+), Ho(3+) samples under UV excitation was first investigated and has been demonstrated to be a resonant type via a quadrupole-quadrupole mechanism. The critical distance (R(Tm-Ho)) is calculated to be 28.4 Å. In addition, the LaOF:Tb(3+) and LaOF:Tm(3+) phosphors exhibit green and blue luminescence with better chromaticity coordinates, color purity, and higher intensity compared with the commercial green phosphor ZnO:Zn and blue phosphor Y(2)SiO(5):Ce(3+) to some extent under low-voltage electron beam excitation.
一系列具有良好分散性的 LaOF:Ln(3+)（Ln = Eu、Tb、Sm、Dy、Tm 和/或 Ho）纳米晶体通过水热法和热处理工艺成功制备。在紫外辐射和低电压电子束激发下，LaOF:Ln(3+)纳米晶体表现出 Ln(3+)（Ln = Eu、Tb、Sm、Dy、Tm 或 Ho）的特征 f-f 发射，并分别发出红色、蓝绿色、橙色、黄色、蓝色和绿色发射。此外，当它们在单相 LaOF 基质中共掺杂时（例如，LaOF:Tb(3+)，Eu(3+)/Sm(3+)；LaOF:Tm(3+)，Dy(3+)/Ho(3+)；LaOF:Tm(3+)，Ho(3+)，Eu(3+)系统），存在 Tb(3+)、Eu(3+)、Sm(3+)、Dy(3+)、Tm(3+)或 Ho(3+)的单独同时发光，这有利于调节发射颜色。在低电压电子束激发下，通过改变掺杂离子和掺杂浓度，可以有效地调整多种颜色，使这些材料在场发射显示器件中有潜在的应用。更重要的是，首次研究了在紫外光激发下，LaOF:Tm(3+)，Ho(3+)样品中 Tm(3+)到 Ho(3+)的能量转移，并通过四极-四极机制证明为共振类型。计算出的临界距离（R(Tm-Ho)）为 28.4 Å。此外，与商用绿色荧光粉 ZnO:Zn 和蓝色荧光粉 Y(2)SiO(5):Ce(3+)相比，LaOF:Tb(3+)和 LaOF:Tm(3+)荧光粉在低电压电子束激发下具有更好的色度坐标、颜色纯度和更高的强度的绿色和蓝色发光。
