Abstract The well-defined GdPO4 hierarchical hollow spheres with uniform size and good dispersity have been fabricated by a facile synthesis strategy. The monodisperse precursor colloidal spheres were firstly obtained by a precipitation route with EG and H2O as mixing solvent. Subsequently, the GdPO4·H2O hollow spheres were synthesized via a hydrothermal conversion process at the expense of the precursor spheres. During the synthesis process, the uniform and well-dispersed precursor spheres not only provide the gadolinium source for the hexagonal GdPO4·H2O but also act as the spherical template for the formation of the hollow spheres. Finally, the monoclinic GdPO4 hollow spheres with enhanced crystallinity were prepared after annealing process in air, which inherit the hollow spherical morphology and good dispersity of the hydrothermal product. Both the down-conversion (DC) and up-conversion (UC) luminescence can be realized by doping appropriate lanthanide activator ions (Ln3+) into the GdPO4host upon ultraviolet (UV) or near-infrared (NIR) excitation. Moreover, the calcined phosphors exhibit stronger emission intensity due to the improved crystallinity. This adopted synthesis strategy may be of significance for the design and preparation of other hollow spherical lanthanide functional materials.

中文翻译：

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镧系离子掺杂磷酸钆分级空心球的简便合成及发光性能

摘要 通过简便的合成策略制备了尺寸均匀、分散性好的明确定义的 GdPO4 分级空心球。单分散前体胶体球首先通过以EG和H2O为混合溶剂的沉淀路线获得。随后，以牺牲前体球体为代价，通过水热转化工艺合成了 GdPO4·H2O 空心球体。在合成过程中，均匀且分散良好的前驱球体不仅为六方GdPO4·H2O提供了钆源，而且作为形成空心球体的球形模板。最后，在空气中退火处理后制备出结晶度增强的单斜GdPO4空心球，它继承了水热产物的空心球形形态和良好的分散性。通过在紫外 (UV) 或近红外 (NIR) 激发下将适当的镧系元素活化剂离子 (Ln3+) 掺杂到 GdPO4 主体中，可以实现下转换 (DC) 和上转换 (UC) 发光。此外，由于提高的结晶度，煅烧的磷光体表现出更强的发射强度。这种采用的合成策略可能对其他中空球形镧系元素功能材料的设计和制备具有重要意义。