Material Processing Division, Bhabha Atomic Research Centre, Trombay, Mumbai, 400085, India.
Nanoscale. 2010 Dec;2(12):2847-54. doi: 10.1039/c0nr00334d. Epub 2010 Oct 11.
Nanorods of Y0.95Eu0.05PO4@CePO4 (Y0.95Eu0.05PO4 phase was nucleated first and then a CePO4 phase was nucleated) and CePO4@Y0.95Eu0.05PO4 (CePO4 phase was nucleated first and then Y0.95Eu0.05PO4 phase was nucleated) were prepared at a relatively low temperature of 140 °C in ethylene glycol medium. Based on XRD, TEM and Raman studies it has been inferred that Y0.95Eu0.05PO4@CePO4 sample consists of a mixture of bigger (length around 800-1000 nm and width around of 80-100 nm) and smaller (length around 70-100 nm and width around 10-20 nm) nanorods, having monoclinic CePO4 and tetragonal YPO4 structure, whereas CePO4@Y0.95Eu0.05PO4 sample consists of mainly small nanorods having a single phase CePO4 structure. From the detailed luminescence studies it has been established that there exists significant incorporation of Y3+/Eu3+ ions in the CePO4 phase in CePO4@Y0.95Eu0.5PO4 sample. This has been attributed to the cation exchange taking place between Ce3+ ions in CePO4 host and Eu3+ and Y3+ ions in solution during the synthesis stage. Unlike this, such an exchange is not possible for Y0.95Eu0.05PO4@CePO4 sample synthesized under identical conditions due to the higher solubility product (Ksp) value of YPO4 compared to CePO4. Incorporation of Eu3+ in the CePO4 lattice of CePO4@Y0.95Eu0.5PO4 sample is confirmed by the significant reduction in the lifetime of 5D0 level of Eu3+ and the luminescence intensity from Eu3+, arising due to the electron transfer between the Ce3+/Ce4+ and Eu3+/Eu2+ species. These results are further supported by the non-radiative decay rates and quantum yields calculated from the emission spectrum.
在乙二醇介质中于相对较低的 140°C 温度下制备了 Y0.95Eu0.05PO4@CePO4（首先成核 Y0.95Eu0.05PO4 相，然后成核 CePO4 相）和 CePO4@Y0.95Eu0.05PO4（首先成核 CePO4 相，然后成核 Y0.95Eu0.05PO4 相）。基于 XRD、TEM 和拉曼研究推断，Y0.95Eu0.05PO4@CePO4 样品由较大（长度约 800-1000nm，宽度约 80-100nm）和较小（长度约 70-100nm，宽度约 10-20nm）纳米棒的混合物组成，具有单斜 CePO4 和四方 YPO4 结构，而 CePO4@Y0.95Eu0.05PO4 样品主要由具有单相 CePO4 结构的小纳米棒组成。从详细的发光研究中可以确定，在 CePO4@Y0.95Eu0.5PO4 样品中 CePO4 相中存在大量的 Y3+/Eu3+离子掺入。这归因于在合成阶段 CePO4 主体中的 Ce3+离子与溶液中的 Eu3+和 Y3+离子之间发生的阳离子交换。与此不同，在相同条件下合成的 Y0.95Eu0.05PO4@CePO4 样品中，由于 YPO4 的溶解度积（Ksp）值高于 CePO4，因此不可能发生这种交换。CePO4@Y0.95Eu0.5PO4 样品中 Eu3+掺入 CePO4 晶格通过 5D0 能级的 Eu3+的寿命显着缩短以及 Eu3+的发光强度得到证实，这是由于 Ce3+/Ce4+和 Eu3+/Eu2+物种之间的电子转移引起的。这些结果还得到了从发射光谱计算出的非辐射衰减率和量子产率的支持。
