采用改进高温热分解法合成了Cd2+掺杂NaLuF4∶Yb, Er纳米晶体,研究了Cd2+对晶相形成和发光强度的影响,采用CASTEP计算不同掺杂浓度下β-NaLuF4∶Yb, Er的形成能。在掺杂浓度为6mol%时合成的纳米晶荧光强度最强,其相较于未掺杂时增加了2.6倍,此时平均尺寸为23 nm左右。随后通过控制添加合适比例和含量的分散剂,解决了晶体易团聚的问题,得到了平均尺寸为18 nm的结晶度高、分散性好的上转换纳米晶。通过二氧化硅壳层的包覆,降低了Cd2+泄露引起的毒性反应,表明在浓度较低时呈现出低毒性,满足了上转换纳米晶在医用材料领域应用的要求。

The Cd2+-doped NaLuF4∶Yb, Er nanocrystals were synthesized by an improved high-temperature thermal decomposition method, and the effects of Cd2+ on crystal phase formation and luminous intensity were studied. The formation energy of β-NaLuF4∶Yb, Er at different doping concentration was calculated by CASTEP. The nanocrystals synthesized at the doping concentration of 6mol% have the strongest fluorescence intensity, which increase by 2.6 times compared to the undoped one. The average size is about 23 nm. Subsequently, the problem of easy agglomeration of crystals was solved by controlling the addition of suitable proportion and content of dispersants, and the up-conversion nanocrystals with high crystallinity and good dispersibility with average size of 18 nm were obtained. The coating of the silica shell layer reduces the toxic reaction caused by Cd2+ leakage, indicating that it exhibits low toxicity when the concentration is low, and meets the requirements of the application of upconversion nanocrystals in the field of medical materials.