采用水热法合成了Yb3+/Er3+共掺杂的BaYF5:上转换发射纳米晶。采用X射线衍射仪和扫描电镜对样品的结构和形貌进行了分析。在980 nm半导体激光器激发下，研究了水热合成温度对BaYF5:Yb3+/Er3+ 材料上转换发光特性的影响。研究结果表明，200 ℃水热合成样品的上转换发光强度达到最大，220 ℃水热合成样品的大小和尺寸均匀，粒径约为100 nm。通过研究光强与抽运功率的双对数曲线发现，523，546，649和667 nm的发射均属于双光子过程。在此基础上讨论了样品的协作敏化和声子辅助共振能量传递的上转换发光机制。

Yb3+ and Er3+ co-doped BaYF5: up-conversion nanocrystals are prepared by hydrothermal method. The sample is characterized by scanning electron microscopy and X-ray diffraction. Upon 980 nm laser diode excitation, the effect of hydrothermal synthesis temperatures on up-conversion luminescence properties is discussed. Results show that the sample obtained at 200 ℃ has larger green emission intensity than that of other samples, while the sample synthesized by hydrothermal method at 220 ℃ has the average grain size about 100 nm. According to the law of luminescence intensity versus excitation power, the 523 and 546 nm green emission, 649 and 667 nm red emission are all due to the double-photon process. The up-conversion mechanism and processes are also analyzed.