supported by the National Natural Science Foundation of China (No. 61805198);the Special Research Projects of Department of Education of Shaanxi Province (No. 18JK0707)。
Li ions affect the upconversion efficiency by changing the local crystal field of the luminescent center. Herein, in order to improve the upconversion efficiency of NaYF4:Yb3+/Eu3+, a series of NaYF4:Yb3+/Eu3+micro-pa...