Visible and ultraviolet upconversion and near infrared downconversion luminescence from lanthanide doped La2Zr2O7 nanoparticles
Visible and ultraviolet upconversion and near infrared downconversion luminescence from lanthanide doped La2Zr2O7 nanoparticles
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DOI：
10.1016/j.jlumin.2019.116591
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发表时间：
2019-10-01
影响因子：
3.6
通讯作者：
Mao, Yuanbing
中科院分区：
文献类型：
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作者：
Gupta, Santosh K.;Garcia, Mitzy A. Penilla;Mao, Yuanbing
通过选择性掺杂而具有多种光物理过程的单一材料由于其多功能的应用，在材料科学界有着很高的需求。稀土掺杂纳米粒子具有广阔的应用前景，其上转换(UC)和下转换(DC)发光特性势在必行。在这里，我们描述了熔盐法合成的两个系列的双掺杂和三掺杂的La2Zr2O7纳米粒子。对于前者，La2Zr2O7：Yb，Er纳米粒子在1550 nm附近显示出鲜红和中绿的UC(VUC)和NIR-B DC(NDC)，这是非常适合体内生物成像应用的。对于后者，La2Zr2O7：Gd，Yb，Tm纳米粒子表现出可用于净水的紫外线UC(UVUC)。此外，我们还系统地研究了敏化剂掺杂水平对这些纳米粒子的形貌、晶体结构以及UC和DC发射强度的影响。通过泵浦功率对VUC、NDC和UVUC发射过程的详细研究，发现VUC发射是双光子过程，而UVUC发射是五光子吸收过程。基于能量转移和f-f跃迁过程，这三种发光过程的机制都得到了广泛的解释。本工作提供的思路扩展了对焦绿石纳米颗粒掺杂诱导的UC和DC发光的认识，显示了发光性质的多功能性。
Single materials which have a multitude of photophysical processes by selective doping are in high demand in the community of material science due to their multifunctional applications. Upconversion (UC) and downconversion (DC) luminescence properties of lanthanide doped nanoparticles (NPs) are imperative for their broad application potentials. Here, we describe two series of either doubly or triply doped La2Zr2O7 NPs synthesized by a molten salt method. For the former, La2Zr2O7:Yb,Er NPs display bright red and moderate green UC (VUC) and NIR-B DC (NDC) at around 1550 nm, which are highly desirable for in-vivo bioimaging applications. For the latter, La2Zr2O7:Gd,Yb,Tm NPs demonstrate ultraviolet UC (UVUC) which can be exploited for water purification. In addition, we systematically investigated the effects of sensitizer doping level on the morphology, crystal structure and UC and DC emission intensity of these NPs. The processes involved in the VUC, NDC and UVUC emissions are evaluated in detail by pump power dependence studies which reveal that the VUC emissions are two-photon processes whereas the UVUC emission is a five-photon absorption process. The mechanisms of all these three luminescence processes have been extensively explained based on energy transfer and f-f transition processes. The idea provided in this work extends the knowledge on doping induced UC and DC luminescence in pyrochlore NPs which show multifunctionalities in light emission properties.