Liang Zhiqin

Phase transformation and morphology tuning of β-NaYF4:Yb3+,Er3+ nanocrystals through K+ ions codoping

In this work, a simple method to modulate the crystal phase and morphology with a large amount of K+ ions codoping is proposed. The phase changes to the mixture of β-NaYF4 and β-KYF4 with increasing the content of K+ ions to 80 mol%. When it exceeds 80 mol%, β-NaYF4 disappears gradually and β-KYF4 dominates with a poor crystalline. In addition, the morphology changes from nanosphere to nanoplate, and then to nanoprism, which indicates that a higher content of K+ ions favors the growth rates along [0001] than the [10-10] of the nanocrystals. Additionally, the upconversion (UC) luminescence properties and the ratio of red/green (R/G) UC intensity of samples with different phases and morphologies are detected, which makes it possible to tune the UC fluorescence by varying the concentration of K+ ions.