利用温和的溶剂热方法合成了具有上转换发光性能的Yb3+-Tm3+和Yb3+-Er3+共掺的纳米NaYGdF4。在该体系中, 通过调节Gd3+在基质中的掺杂量可以有效地控制产物的相变、尺寸以及上转换荧光性能。XRD和TEM分析结果表明, Gd3+的掺入在促进NaYF4纳米颗粒由立方相到六方相转变的同时有助于减小其尺寸。上转换光谱研究表明, 在Yb3+-Tm3+和Yb3+-Er3+共掺体系中, 可通过优化Gd3+的掺杂量来有效提高产物的上转换荧光强度。同时, 通过研究Tm3+和Er3+在不同可见光波段的发光强度与泵浦功率的关系探讨了上转换发光的机制。

A series of Yb3+-Tm3+ and Yb3+-Er3+ codoped NaYGdF4 upconversion luminescent nanoparticles were prepared via a facile modified solvothermal method. The phase (cubic or hexagonal), size and upconversion luminescence properties of the final products can be well controlled by adjusting Gd3+ content. The introduction of Gd3+ can effectively promote the hexagonal to cubic phase transformation and size reduction of NaYGdF4 nanocrystals. The upconversion emission intensity of NaYGdF4∶Yb3+,Er3+/Tm3+can be improved by optimizing Gd3+ content. Meanwhile, the upconversion mechanism was discussed by studying the excitation power dependent visible emission intensity of Tm3+ and Er3+ in different wavelength regions.