采用共沉淀法合成了尺寸小于10 nm的Yb3+/Ln3+(Ln=Ho3+，Tm3+)掺杂β-NaYF4核纳米晶，在此基础上构建了NaYF4∶Yb3+,Ln3+@NaYF4∶Yb3+@NaYF4核-双层壳结构纳米晶，并通过XRD和TEM测试证明了中间活性壳和最外层惰性壳的成功包覆。光谱结果表明，在活性核和活性壳中分别掺杂Yb3+、并进一步生长最外层的惰性壳能够有效地提高Ho3+和Tm3+的上转换发射强度，这是由核-双层壳结构纳米晶对980 nm激发光的吸收增强以及Yb3+浓度猝灭阈值的提高所引起的高效能量传递共同导致的。此外，通过调节中间壳层中的Yb3+掺杂浓度，可以获得高效可调发光。本研究为开发多色高效上转换发光纳米晶提供了一条有效的途径。

In this research, the Yb3+/Ln3+ (Ln=Ho3+ and Tm3+) doped β-NaYF4 core nanocrystals(NCs) with sub-10 nm size were synthesized with co-precipitation method, based on which the core-shell-shell structured NaYF4∶Yb3+,Ln3+ @ NaYF4∶Yb3+@NaYF4 NCs were constructed. The successfully growth of the middle active-shell and the outmost inert-shell were proved by XRD and TEM measurements. The spectral results indicated that partially isolate Yb3+ dopant in active-core and active-shell and the growth of the outmost inert-shell can effectively improve the upconversion(UC) emission intensity of Ho3+ and Tm3+, which is resulted from the enhanced absorption of 980 nm excitation light and energy transfer efficiency ascribing to the increased Yb3+ concentration quenching threshold. Moreover, through adjusting Yb3+ doping concentration in the middle-shell, the tunable emission can be obtained. This research suggested a general route for the development of highly-efficient luminescent upconversion nanocrystals(UCNCs) in a broad color range.